記事編集

日付

ジャンルのカテゴリ―名

タイトル

内容の要旨

<p style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: 4px; padding: revert; -webkit-line-clamp: revert; color: rgba(0, 0, 0, 0.8); font-family: roboto, helvetica, sans-serif; font-size: 16px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;" data-pasted="true">了解です。<br>では、前回の多階層ドロップダウン実装を、さらに<strong style="font-weight: 700;">実務向けに改良</strong>して再生成します。<br>今回は以下の点を追加します。</p><ul style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: revert; padding: revert; color: rgba(0, 0, 0, 0.8); font-family: roboto, helvetica, sans-serif; font-size: 16px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><li style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin-top: revert; margin-right: revert; margin-bottom: 8px; margin-left: revert; padding: revert;"><strong style="font-weight: 700;">非同期ロード対応（Ajax）</strong>：親カテゴリ選択時に子カテゴリを動的取得</li><li style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin-top: revert; margin-right: revert; margin-bottom: 8px; margin-left: revert; padding: revert;"><strong style="font-weight: 700;">APIエンドポイント追加</strong>：JSONで階層データを返す</li><li style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin-top: revert; margin-right: revert; margin-bottom: 8px; margin-left: revert; padding: revert;"><strong style="font-weight: 700;">Viewは初期表示を最小限に</strong>：必要な階層だけ読み込む</li></ul><h2 style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: revert; padding: revert; font: 22px / 24px roboto, helvetica, sans-serif; height: 32px; -webkit-line-clamp: 1; overflow: hidden; text-overflow: ellipsis; display: -webkit-box; -webkit-box-orient: vertical; color: rgba(0, 0, 0, 0.8); letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">1. モデル（DBエンティティ）</h2><pre data-priority="2" style="background: none 0% 0% / auto repeat scroll padding-box border-box rgb(245, 245, 245); border: 1px solid rgba(0, 0, 0, 0.1); border-radius: 8px; overflow: hidden; color: rgba(0, 0, 0, 0.8); font-size: 16px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><div data-bm="107" style="display: flex; height: 28px; flex-direction: row; justify-content: space-between; align-items: center; gap: 8px; padding: 8px 12px; border-bottom: 1px solid rgba(0, 0, 0, 0.1); background: none 0% 0% / auto repeat scroll padding-box border-box rgb(243, 249, 254);"><h5 style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: 0px; padding: revert; font-style: normal !important; font-variant: normal !important; font-weight: 400 !important; font-stretch: 100% !important; line-height: 18px; font-family: roboto, helvetica, sans-serif !important; font-optical-sizing: auto !important; font-size-adjust: none !important; font-kerning: auto !important; font-feature-settings: normal !important; font-variation-settings: normal !important; font-language-override: normal !important; font-size: 16px; display: inline-block; color: rgb(11, 73, 127);">Csharp</h5><div style="height: 28px;"><button type="button" tabindex="" title="Copy code" style="box-sizing: border-box; margin: 0px; padding: 0px; font: 400 13px / 20px roboto, helvetica, sans-serif; background-color: rgb(225, 240, 253); border: 1px solid rgba(0, 0, 0, 0); display: grid; grid-auto-flow: column; align-items: center; cursor: pointer; color: rgb(0, 0, 0) !important; text-decoration: none !important; border-radius: 9999px; block-size: 28px; gap: 2px; padding-inline: 10px;"><div style="box-sizing: border-box; margin: 0px; padding: 0px; min-inline-size: 0px; max-inline-size: 100%; white-space: nowrap; text-overflow: ellipsis; overflow: clip; max-block-size: calc(1lh); padding-inline: 2px;">Copy code</div></button></div></div><code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255); display: block; white-space: pre-wrap; overflow-wrap: anywhere; padding: 8px 16px 16px;"><span style="color: rgb(106, 115, 125);">// Models/Category.cs</span>
<span style="color: rgb(215, 58, 73);">using</span> System.Collections.Generic;
<span style="color: rgb(215, 58, 73);">using</span> System.ComponentModel.DataAnnotations;

<span style="color: rgb(215, 58, 73);">public</span> <span style="color: rgb(215, 58, 73);">class</span> <span style="color: rgb(111, 66, 193);">Category</span>
{
    <span style="color: rgb(215, 58, 73);">public</span> <span style="color: rgb(227, 98, 9);">int</span> Id { <span style="color: rgb(215, 58, 73);">get</span>; <span style="color: rgb(215, 58, 73);">set</span>; }

    [<span style="color: rgb(0, 92, 197);">Required</span>]
    <span style="color: rgb(215, 58, 73);">public</span> <span style="color: rgb(227, 98, 9);">string</span> Name { <span style="color: rgb(215, 58, 73);">get</span>; <span style="color: rgb(215, 58, 73);">set</span>; }

    <span style="color: rgb(215, 58, 73);">public</span> <span style="color: rgb(227, 98, 9);">int</span>? ParentId { <span style="color: rgb(215, 58, 73);">get</span>; <span style="color: rgb(215, 58, 73);">set</span>; }

    <span style="color: rgb(215, 58, 73);">public</span> Category Parent { <span style="color: rgb(215, 58, 73);">get</span>; <span style="color: rgb(215, 58, 73);">set</span>; }
    <span style="color: rgb(215, 58, 73);">public</span> ICollection&lt;Category&gt; Children { <span style="color: rgb(215, 58, 73);">get</span>; <span style="color: rgb(215, 58, 73);">set</span>; } = <span style="color: rgb(215, 58, 73);">new</span> List&lt;Category&gt;();
}
</code></pre><h2 style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: revert; padding: revert; font: 22px / 24px roboto, helvetica, sans-serif; height: 32px; -webkit-line-clamp: 1; overflow: hidden; text-overflow: ellipsis; display: -webkit-box; -webkit-box-orient: vertical; color: rgba(0, 0, 0, 0.8); letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">2. DbContext</h2><pre data-priority="2" style="background: none 0% 0% / auto repeat scroll padding-box border-box rgb(245, 245, 245); border: 1px solid rgba(0, 0, 0, 0.1); border-radius: 8px; overflow: hidden; color: rgba(0, 0, 0, 0.8); font-size: 16px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><div data-bm="108" style="display: flex; height: 28px; flex-direction: row; justify-content: space-between; align-items: center; gap: 8px; padding: 8px 12px; border-bottom: 1px solid rgba(0, 0, 0, 0.1); background: none 0% 0% / auto repeat scroll padding-box border-box rgb(243, 249, 254);"><h5 style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: 0px; padding: revert; font-style: normal !important; font-variant: normal !important; font-weight: 400 !important; font-stretch: 100% !important; line-height: 18px; font-family: roboto, helvetica, sans-serif !important; font-optical-sizing: auto !important; font-size-adjust: none !important; font-kerning: auto !important; font-feature-settings: normal !important; font-variation-settings: normal !important; font-language-override: normal !important; font-size: 16px; display: inline-block; color: rgb(11, 73, 127);">Csharp</h5><div style="height: 28px;"><button type="button" tabindex="" title="Copy code" style="box-sizing: border-box; margin: 0px; padding: 0px; font: 400 13px / 20px roboto, helvetica, sans-serif; background-color: rgb(225, 240, 253); border: 1px solid rgba(0, 0, 0, 0); display: grid; grid-auto-flow: column; align-items: center; cursor: pointer; color: rgb(0, 0, 0) !important; text-decoration: none !important; border-radius: 9999px; block-size: 28px; gap: 2px; padding-inline: 10px;"><div style="box-sizing: border-box; margin: 0px; padding: 0px; min-inline-size: 0px; max-inline-size: 100%; white-space: nowrap; text-overflow: ellipsis; overflow: clip; max-block-size: calc(1lh); padding-inline: 2px;">Copy code</div></button></div></div><code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255); display: block; white-space: pre-wrap; overflow-wrap: anywhere; padding: 8px 16px 16px;"><span style="color: rgb(106, 115, 125);">// Data/ApplicationDbContext.cs</span>
<span style="color: rgb(215, 58, 73);">using</span> Microsoft.EntityFrameworkCore;

<span style="color: rgb(215, 58, 73);">public</span> <span style="color: rgb(215, 58, 73);">class</span> <span style="color: rgb(111, 66, 193);">ApplicationDbContext</span> : <span style="color: rgb(111, 66, 193);">DbContext</span>
{
    <span style="color: rgb(215, 58, 73);">public</span> <span style="color: rgb(111, 66, 193);">ApplicationDbContext</span>(DbContextOptions&lt;ApplicationDbContext&gt; options)
        : <span style="color: rgb(111, 66, 193);">base</span>(options) { }

    <span style="color: rgb(215, 58, 73);">public</span> DbSet&lt;Category&gt; Categories { <span style="color: rgb(215, 58, 73);">get</span>; <span style="color: rgb(215, 58, 73);">set</span>; }
}
</code></pre><h2 style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: revert; padding: revert; font: 22px / 24px roboto, helvetica, sans-serif; height: 32px; -webkit-line-clamp: 1; overflow: hidden; text-overflow: ellipsis; display: -webkit-box; -webkit-box-orient: vertical; color: rgba(0, 0, 0, 0.8); letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">3. サービス（子カテゴリ取得）</h2><pre data-priority="2" style="background: none 0% 0% / auto repeat scroll padding-box border-box rgb(245, 245, 245); border: 1px solid rgba(0, 0, 0, 0.1); border-radius: 8px; overflow: hidden; color: rgba(0, 0, 0, 0.8); font-size: 16px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><div data-bm="109" style="display: flex; height: 28px; flex-direction: row; justify-content: space-between; align-items: center; gap: 8px; padding: 8px 12px; border-bottom: 1px solid rgba(0, 0, 0, 0.1); background: none 0% 0% / auto repeat scroll padding-box border-box rgb(243, 249, 254);"><h5 style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: 0px; padding: revert; font-style: normal !important; font-variant: normal !important; font-weight: 400 !important; font-stretch: 100% !important; line-height: 18px; font-family: roboto, helvetica, sans-serif !important; font-optical-sizing: auto !important; font-size-adjust: none !important; font-kerning: auto !important; font-feature-settings: normal !important; font-variation-settings: normal !important; font-language-override: normal !important; font-size: 16px; display: inline-block; color: rgb(11, 73, 127);">Csharp</h5><div style="height: 28px;"><button type="button" tabindex="" title="Copy code" style="box-sizing: border-box; margin: 0px; padding: 0px; font: 400 13px / 20px roboto, helvetica, sans-serif; background-color: rgb(225, 240, 253); border: 1px solid rgba(0, 0, 0, 0); display: grid; grid-auto-flow: column; align-items: center; cursor: pointer; color: rgb(0, 0, 0) !important; text-decoration: none !important; border-radius: 9999px; block-size: 28px; gap: 2px; padding-inline: 10px;"><div style="box-sizing: border-box; margin: 0px; padding: 0px; min-inline-size: 0px; max-inline-size: 100%; white-space: nowrap; text-overflow: ellipsis; overflow: clip; max-block-size: calc(1lh); padding-inline: 2px;">Copy code</div></button></div></div><code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255); display: block; white-space: pre-wrap; overflow-wrap: anywhere; padding: 8px 16px 16px;"><span style="color: rgb(106, 115, 125);">// Services/CategoryService.cs</span>
<span style="color: rgb(215, 58, 73);">using</span> Microsoft.EntityFrameworkCore;
<span style="color: rgb(215, 58, 73);">using</span> System.Collections.Generic;
<span style="color: rgb(215, 58, 73);">using</span> System.Linq;
<span style="color: rgb(215, 58, 73);">using</span> System.Threading.Tasks;

<span style="color: rgb(215, 58, 73);">public</span> <span style="color: rgb(215, 58, 73);">class</span> <span style="color: rgb(111, 66, 193);">CategoryService</span>
{
    <span style="color: rgb(215, 58, 73);">private</span> <span style="color: rgb(215, 58, 73);">readonly</span> ApplicationDbContext _context;

    <span style="color: rgb(215, 58, 73);">public</span> <span style="color: rgb(111, 66, 193);">CategoryService</span>(ApplicationDbContext context)
    {
        _context = context;
    }

    <span style="color: rgb(215, 58, 73);">public</span> <span style="color: rgb(215, 58, 73);">async</span> Task&lt;List&lt;Category&gt;&gt; GetTopLevelCategoriesAsync()
    {
        <span style="color: rgb(215, 58, 73);">return</span> <span style="color: rgb(215, 58, 73);">await</span> _context.Categories
            .Where(c =&gt; c.ParentId == <span style="color: rgb(0, 92, 197);">null</span>)
            .OrderBy(c =&gt; c.Name)
            .ToListAsync();
    }

    <span style="color: rgb(215, 58, 73);">public</span> <span style="color: rgb(215, 58, 73);">async</span> Task&lt;List&lt;Category&gt;&gt; GetChildrenAsync(<span style="color: rgb(227, 98, 9);">int</span> parentId)
    {
        <span style="color: rgb(215, 58, 73);">return</span> <span style="color: rgb(215, 58, 73);">await</span> _context.Categories
            .Where(c =&gt; c.ParentId == parentId)
            .OrderBy(c =&gt; c.Name)
            .ToListAsync();
    }
}
</code></pre><h2 style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: revert; padding: revert; font: 22px / 24px roboto, helvetica, sans-serif; height: 32px; -webkit-line-clamp: 1; overflow: hidden; text-overflow: ellipsis; display: -webkit-box; -webkit-box-orient: vertical; color: rgba(0, 0, 0, 0.8); letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">4. コントローラー（通常View + API）</h2><pre data-priority="2" style="background: none 0% 0% / auto repeat scroll padding-box border-box rgb(245, 245, 245); border: 1px solid rgba(0, 0, 0, 0.1); border-radius: 8px; overflow: hidden; color: rgba(0, 0, 0, 0.8); font-size: 16px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><div data-bm="110" style="display: flex; height: 28px; flex-direction: row; justify-content: space-between; align-items: center; gap: 8px; padding: 8px 12px; border-bottom: 1px solid rgba(0, 0, 0, 0.1); background: none 0% 0% / auto repeat scroll padding-box border-box rgb(243, 249, 254);"><h5 style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: 0px; padding: revert; font-style: normal !important; font-variant: normal !important; font-weight: 400 !important; font-stretch: 100% !important; line-height: 18px; font-family: roboto, helvetica, sans-serif !important; font-optical-sizing: auto !important; font-size-adjust: none !important; font-kerning: auto !important; font-feature-settings: normal !important; font-variation-settings: normal !important; font-language-override: normal !important; font-size: 16px; display: inline-block; color: rgb(11, 73, 127);">Csharp</h5><div style="height: 28px;"><button type="button" tabindex="" title="Copy code" style="box-sizing: border-box; margin: 0px; padding: 0px; font: 400 13px / 20px roboto, helvetica, sans-serif; background-color: rgb(225, 240, 253); border: 1px solid rgba(0, 0, 0, 0); display: grid; grid-auto-flow: column; align-items: center; cursor: pointer; color: rgb(0, 0, 0) !important; text-decoration: none !important; border-radius: 9999px; block-size: 28px; gap: 2px; padding-inline: 10px;"><div style="box-sizing: border-box; margin: 0px; padding: 0px; min-inline-size: 0px; max-inline-size: 100%; white-space: nowrap; text-overflow: ellipsis; overflow: clip; max-block-size: calc(1lh); padding-inline: 2px;">Copy code</div></button></div></div><code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255); display: block; white-space: pre-wrap; overflow-wrap: anywhere; padding: 8px 16px 16px;"><span style="color: rgb(106, 115, 125);">// Controllers/MenuController.cs</span>
<span style="color: rgb(215, 58, 73);">using</span> Microsoft.AspNetCore.Mvc;
<span style="color: rgb(215, 58, 73);">using</span> System.Threading.Tasks;

<span style="color: rgb(215, 58, 73);">public</span> <span style="color: rgb(215, 58, 73);">class</span> <span style="color: rgb(111, 66, 193);">MenuController</span> : <span style="color: rgb(111, 66, 193);">Controller</span>
{
    <span style="color: rgb(215, 58, 73);">private</span> <span style="color: rgb(215, 58, 73);">readonly</span> CategoryService _categoryService;

    <span style="color: rgb(215, 58, 73);">public</span> <span style="color: rgb(111, 66, 193);">MenuController</span>(CategoryService categoryService)
    {
        _categoryService = categoryService;
    }

    <span style="color: rgb(106, 115, 125);">// 初期表示（親カテゴリのみ）</span>
    <span style="color: rgb(215, 58, 73);">public</span> <span style="color: rgb(215, 58, 73);">async</span> Task&lt;IActionResult&gt; <span style="color: rgb(111, 66, 193);">Index</span>()
    {
        <span style="color: rgb(215, 58, 73);">var</span> parents = <span style="color: rgb(215, 58, 73);">await</span> _categoryService.GetTopLevelCategoriesAsync();
        <span style="color: rgb(215, 58, 73);">return</span> View(parents);
    }

    <span style="color: rgb(106, 115, 125);">// API: 子カテゴリ取得</span>
    [<span style="color: rgb(0, 92, 197);">HttpGet</span>]
    <span style="color: rgb(215, 58, 73);">public</span> <span style="color: rgb(215, 58, 73);">async</span> Task&lt;IActionResult&gt; <span style="color: rgb(111, 66, 193);">GetChildren</span>(<span style="color: rgb(227, 98, 9);">int</span> parentId)
    {
        <span style="color: rgb(215, 58, 73);">var</span> children = <span style="color: rgb(215, 58, 73);">await</span> _categoryService.GetChildrenAsync(parentId);
        <span style="color: rgb(215, 58, 73);">return</span> Json(children.Select(c =&gt; <span style="color: rgb(215, 58, 73);">new</span> { c.Id, c.Name }));
    }
}
</code></pre><h2 style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: revert; padding: revert; font: 22px / 24px roboto, helvetica, sans-serif; height: 32px; -webkit-line-clamp: 1; overflow: hidden; text-overflow: ellipsis; display: -webkit-box; -webkit-box-orient: vertical; color: rgba(0, 0, 0, 0.8); letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">5. View（Ajax連動ドロップダウン）</h2><pre data-priority="2" style="background: none 0% 0% / auto repeat scroll padding-box border-box rgb(245, 245, 245); border: 1px solid rgba(0, 0, 0, 0.1); border-radius: 8px; overflow: hidden; color: rgba(0, 0, 0, 0.8); font-size: 16px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><div data-bm="111" style="display: flex; height: 28px; flex-direction: row; justify-content: space-between; align-items: center; gap: 8px; padding: 8px 12px; border-bottom: 1px solid rgba(0, 0, 0, 0.1); background: none 0% 0% / auto repeat scroll padding-box border-box rgb(243, 249, 254);"><h5 style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: 0px; padding: revert; font-style: normal !important; font-variant: normal !important; font-weight: 400 !important; font-stretch: 100% !important; line-height: 18px; font-family: roboto, helvetica, sans-serif !important; font-optical-sizing: auto !important; font-size-adjust: none !important; font-kerning: auto !important; font-feature-settings: normal !important; font-variation-settings: normal !important; font-language-override: normal !important; font-size: 16px; display: inline-block; color: rgb(11, 73, 127);">Html</h5><div style="height: 28px;"><button type="button" tabindex="" title="Copy code" style="box-sizing: border-box; margin: 0px; padding: 0px; font: 400 13px / 20px roboto, helvetica, sans-serif; background-color: rgb(225, 240, 253); border: 1px solid rgba(0, 0, 0, 0); display: grid; grid-auto-flow: column; align-items: center; cursor: pointer; color: rgb(0, 0, 0) !important; text-decoration: none !important; border-radius: 9999px; block-size: 28px; gap: 2px; padding-inline: 10px;"><div style="box-sizing: border-box; margin: 0px; padding: 0px; min-inline-size: 0px; max-inline-size: 100%; white-space: nowrap; text-overflow: ellipsis; overflow: clip; max-block-size: calc(1lh); padding-inline: 2px;">Copy code</div></button></div></div><code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255); display: block; white-space: pre-wrap; overflow-wrap: anywhere; padding: 8px 16px 16px;">@model List&lt;<span style="color: rgb(34, 134, 58);">Category</span>&gt;

&lt;<span style="color: rgb(34, 134, 58);">select</span> <span style="color: rgb(0, 92, 197);">id</span>=<span style="color: rgb(3, 47, 98);">&quot;parentCategory&quot;</span> <span style="color: rgb(0, 92, 197);">class</span>=<span style="color: rgb(3, 47, 98);">&quot;form-select&quot;</span>&gt;
    &lt;<span style="color: rgb(34, 134, 58);">option</span> <span style="color: rgb(0, 92, 197);">value</span>=<span style="color: rgb(3, 47, 98);">&quot;&quot;</span>&gt;-- 親カテゴリを選択 --&lt;/<span style="color: rgb(34, 134, 58);">option</span>&gt;
    @foreach (var parent in Model)
    {
        &lt;<span style="color: rgb(34, 134, 58);">option</span> <span style="color: rgb(0, 92, 197);">value</span>=<span style="color: rgb(3, 47, 98);">&quot;@parent.Id&quot;</span>&gt;@parent.Name&lt;/<span style="color: rgb(34, 134, 58);">option</span>&gt;
    }
&lt;/<span style="color: rgb(34, 134, 58);">select</span>&gt;

&lt;<span style="color: rgb(34, 134, 58);">select</span> <span style="color: rgb(0, 92, 197);">id</span>=<span style="color: rgb(3, 47, 98);">&quot;childCategory&quot;</span> <span style="color: rgb(0, 92, 197);">class</span>=<span style="color: rgb(3, 47, 98);">&quot;form-select mt-2&quot;</span> <span style="color: rgb(0, 92, 197);">disabled</span>&gt;
    &lt;<span style="color: rgb(34, 134, 58);">option</span> <span style="color: rgb(0, 92, 197);">value</span>=<span style="color: rgb(3, 47, 98);">&quot;&quot;</span>&gt;-- 子カテゴリを選択 --&lt;/<span style="color: rgb(34, 134, 58);">option</span>&gt;
&lt;/<span style="color: rgb(34, 134, 58);">select</span>&gt;

@section Scripts {
&lt;<span style="color: rgb(34, 134, 58);">script</span> <span style="color: rgb(0, 92, 197);">src</span>=<span style="color: rgb(3, 47, 98);">&quot;https://code.jquery.com/jquery-3.6.0.min.js&quot;</span>&gt;&lt;/<span style="color: rgb(34, 134, 58);">script</span>&gt;
&lt;<span style="color: rgb(34, 134, 58);">script</span>&gt;
$(<span style="color: rgb(215, 58, 73);">function</span>(){
    $(<span style="color: rgb(3, 47, 98);">&#39;#parentCategory&#39;</span>).<span style="color: rgb(111, 66, 193);">on</span>(<span style="color: rgb(3, 47, 98);">&#39;change&#39;</span>, <span style="color: rgb(215, 58, 73);">function</span>(){
        <span style="color: rgb(215, 58, 73);">var</span> parentId = $(<span style="color: rgb(215, 58, 73);">this</span>).<span style="color: rgb(111, 66, 193);">val</span>();
        <span style="color: rgb(215, 58, 73);">var</span> $child = $(<span style="color: rgb(3, 47, 98);">&#39;#childCategory&#39;</span>);
        $child.<span style="color: rgb(111, 66, 193);">empty</span>().<span style="color: rgb(111, 66, 193);">append</span>(<span style="color: rgb(3, 47, 98);">&#39;&lt;option value=&quot;&quot;&gt;-- 子カテゴリを選択 --&lt;/option&gt;&#39;</span>);

        <span style="color: rgb(215, 58, 73);">if</span>(parentId){
            $.<span style="color: rgb(111, 66, 193);">getJSON</span>(<span style="color: rgb(3, 47, 98);">&#39;/Menu/GetChildren&#39;</span>, { <span style="color: rgb(0, 92, 197);">parentId</span>: parentId }, <span style="color: rgb(215, 58, 73);">function</span>(data){
                <span style="color: rgb(215, 58, 73);">if</span>(data.length &gt; <span style="color: rgb(0, 92, 197);">0</span>){
                    $.<span style="color: rgb(111, 66, 193);">each</span>(data, <span style="color: rgb(215, 58, 73);">function</span>(i, item){
                        $child.<span style="color: rgb(111, 66, 193);">append</span>($(<span style="color: rgb(3, 47, 98);">&#39;&lt;option&gt;&#39;</span>, { <span style="color: rgb(0, 92, 197);">value</span>: item.id, <span style="color: rgb(0, 92, 197);">text</span>: item.name }));
                    });
                    $child.<span style="color: rgb(111, 66, 193);">prop</span>(<span style="color: rgb(3, 47, 98);">&#39;disabled&#39;</span>, <span style="color: rgb(0, 92, 197);">false</span>);
                } <span style="color: rgb(215, 58, 73);">else</span> {
                    $child.<span style="color: rgb(111, 66, 193);">prop</span>(<span style="color: rgb(3, 47, 98);">&#39;disabled&#39;</span>, <span style="color: rgb(0, 92, 197);">true</span>);
                }
            });
        } <span style="color: rgb(215, 58, 73);">else</span> {
            $child.<span style="color: rgb(111, 66, 193);">prop</span>(<span style="color: rgb(3, 47, 98);">&#39;disabled&#39;</span>, <span style="color: rgb(0, 92, 197);">true</span>);
        }
    });
});
&lt;/<span style="color: rgb(34, 134, 58);">script</span>&gt;
}
</code></pre><h2 style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: revert; padding: revert; font: 22px / 24px roboto, helvetica, sans-serif; height: 32px; -webkit-line-clamp: 1; overflow: hidden; text-overflow: ellipsis; display: -webkit-box; -webkit-box-orient: vertical; color: rgba(0, 0, 0, 0.8); letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">6. Program.cs</h2><pre data-priority="2" style="background: none 0% 0% / auto repeat scroll padding-box border-box rgb(245, 245, 245); border: 1px solid rgba(0, 0, 0, 0.1); border-radius: 8px; overflow: hidden; color: rgba(0, 0, 0, 0.8); font-size: 16px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><div data-bm="112" style="display: flex; height: 28px; flex-direction: row; justify-content: space-between; align-items: center; gap: 8px; padding: 8px 12px; border-bottom: 1px solid rgba(0, 0, 0, 0.1); background: none 0% 0% / auto repeat scroll padding-box border-box rgb(243, 249, 254);"><h5 style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: 0px; padding: revert; font-style: normal !important; font-variant: normal !important; font-weight: 400 !important; font-stretch: 100% !important; line-height: 18px; font-family: roboto, helvetica, sans-serif !important; font-optical-sizing: auto !important; font-size-adjust: none !important; font-kerning: auto !important; font-feature-settings: normal !important; font-variation-settings: normal !important; font-language-override: normal !important; font-size: 16px; display: inline-block; color: rgb(11, 73, 127);">Csharp</h5><div style="height: 28px;"><button type="button" tabindex="" title="Copy code" style="box-sizing: border-box; margin: 0px; padding: 0px; font: 400 13px / 20px roboto, helvetica, sans-serif; background-color: rgb(225, 240, 253); border: 1px solid rgba(0, 0, 0, 0); display: grid; grid-auto-flow: column; align-items: center; cursor: pointer; color: rgb(0, 0, 0) !important; text-decoration: none !important; border-radius: 9999px; block-size: 28px; gap: 2px; padding-inline: 10px;"><div style="box-sizing: border-box; margin: 0px; padding: 0px; min-inline-size: 0px; max-inline-size: 100%; white-space: nowrap; text-overflow: ellipsis; overflow: clip; max-block-size: calc(1lh); padding-inline: 2px;">Copy code</div></button></div></div><code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255); display: block; white-space: pre-wrap; overflow-wrap: anywhere; padding: 8px 16px 16px;"><span style="color: rgb(215, 58, 73);">using</span> Microsoft.EntityFrameworkCore;

<span style="color: rgb(215, 58, 73);">var</span> builder = WebApplication.CreateBuilder(args);

builder.Services.AddDbContext&lt;ApplicationDbContext&gt;(options =&gt;
    options.UseSqlServer(builder.Configuration.GetConnectionString(<span style="color: rgb(3, 47, 98);">&quot;DefaultConnection&quot;</span>)));

builder.Services.AddScoped&lt;CategoryService&gt;();
builder.Services.AddControllersWithViews();

<span style="color: rgb(215, 58, 73);">var</span> app = builder.Build();
app.MapDefaultControllerRoute();
app.Run();
</code></pre><h3 style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: revert; padding: revert; display: inline-block; font: 400 20px / 22px roboto, helvetica, sans-serif; color: rgba(0, 0, 0, 0.8); letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">改良ポイント</h3><ol style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: revert; padding: revert; color: rgba(0, 0, 0, 0.8); font-family: roboto, helvetica, sans-serif; font-size: 16px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><li style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin-top: revert; margin-right: revert; margin-bottom: 8px; margin-left: revert; padding: revert;"><strong style="font-weight: 700;">初期表示は親カテゴリのみ</strong><ul style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: revert; padding: revert;"><li style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin-top: revert; margin-right: revert; margin-bottom: 8px; margin-left: revert; padding: revert;">ページロード時に全階層を読み込まず、軽量化。</li></ul></li><li style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin-top: revert; margin-right: revert; margin-bottom: 8px; margin-left: revert; padding: revert;"><strong style="font-weight: 700;">Ajaxで子カテゴリ取得</strong><ul style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: revert; padding: revert;"><li style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin-top: revert; margin-right: revert; margin-bottom: 8px; margin-left: revert; padding: revert;">必要なときだけサーバーから取得し、パフォーマンス向上。</li></ul></li><li style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin-top: revert; margin-right: revert; margin-bottom: 8px; margin-left: revert; padding: revert;"><strong style="font-weight: 700;">APIエンドポイント分離</strong><ul style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: revert; padding: revert;"><li style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin-top: revert; margin-right: revert; margin-bottom: 8px; margin-left: revert; padding: revert;"><code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">/Menu/GetChildren</code>でJSON返却、他のUIにも流用可能。</li></ul></li></ol><p style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: 4px; padding: revert; -webkit-line-clamp: revert; color: rgba(0, 0, 0, 0.8); font-family: roboto, helvetica, sans-serif; font-size: 16px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">この構成なら、カテゴリ数が多くても高速に動作し、<br>UIも親カテゴリ選択後に必要な子カテゴリだけ表示できます。</p><p style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: 4px; padding: revert; -webkit-line-clamp: revert; color: rgba(0, 0, 0, 0.8); font-family: roboto, helvetica, sans-serif; font-size: 16px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(255, 255, 255); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">もし希望なら、このAjax版を<strong style="font-weight: 700;">孫カテゴリまで連動</strong>する3階層ドロップダウンに拡張できます。<br>作りますか？<br>そうすれば「親 &rarr; 子 &rarr; 孫」まで自動連動します。</p><p data-f-id="pbf" style="text-align: center; font-size: 14px; margin-top: 30px; opacity: 0.65; font-family: sans-serif;">Powered by <a href="https://www.froala.com/wysiwyg-editor?pb=1" title="Froala Editor">Froala Editor</a></p>

添付画像

画像を変更

Back to List

//検索文：Editor内でHTMLコードをコピーさせる