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 data-bm="53" 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">実装するには、<br>以下のように&nbsp;<strong style="font-weight: 700;">View + Controller + JavaScript(AJAX)</strong> を組み合わせるのが一般的です。</p><h2 data-bm="54" 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. データモデル例</h2><p data-bm="55" 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;">親（Category）と子（SubCategory）のリレーションを想定します。</p><pre data-priority="2" data-bm="56" 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="68" 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(248, 244, 241);"><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(60, 81, 180);">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(217, 223, 251); border: 1px solid rgba(0, 0, 0, 0); display: grid; grid-auto-flow: column; align-items: center; cursor: pointer; color: rgb(60, 81, 180) !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);">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(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(227, 98, 9);">string</span>.Empty;

    <span style="color: rgb(215, 58, 73);">public</span> ICollection&lt;SubCategory&gt; SubCategories { <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;SubCategory&gt;();
}

<span style="color: rgb(106, 115, 125);">// Models/SubCategory.cs</span>
<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);">SubCategory</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(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(227, 98, 9);">string</span>.Empty;

    <span style="color: rgb(215, 58, 73);">public</span> <span style="color: rgb(227, 98, 9);">int</span> CategoryId { <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 Category { <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);">null</span>!;
}
</code></pre><h2 data-bm="57" 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 設定</h2><pre data-priority="2" data-bm="58" 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="69" 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(248, 244, 241);"><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(60, 81, 180);">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(217, 223, 251); border: 1px solid rgba(0, 0, 0, 0); display: grid; grid-auto-flow: column; align-items: center; cursor: pointer; color: rgb(60, 81, 180) !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/AppDbContext.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);">AppDbContext</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);">AppDbContext</span>(DbContextOptions&lt;AppDbContext&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>; }
    <span style="color: rgb(215, 58, 73);">public</span> DbSet&lt;SubCategory&gt; SubCategories { <span style="color: rgb(215, 58, 73);">get</span>; <span style="color: rgb(215, 58, 73);">set</span>; }
}
</code></pre><h2 data-bm="59" 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. コントローラー</h2><pre data-priority="2" data-bm="60" 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="70" 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(248, 244, 241);"><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(60, 81, 180);">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(217, 223, 251); border: 1px solid rgba(0, 0, 0, 0); display: grid; grid-auto-flow: column; align-items: center; cursor: pointer; color: rgb(60, 81, 180) !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/ProductController.cs</span>
<span style="color: rgb(215, 58, 73);">using</span> Microsoft.AspNetCore.Mvc;
<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);">ProductController</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> AppDbContext _context;

    <span style="color: rgb(215, 58, 73);">public</span> <span style="color: rgb(111, 66, 193);">ProductController</span>(AppDbContext context)
    {
        _context = context;
    }

    <span style="color: rgb(106, 115, 125);">// 初期表示</span>
    <span style="color: rgb(215, 58, 73);">public</span> IActionResult <span style="color: rgb(111, 66, 193);">Create</span>()
    {
        ViewBag.Categories = _context.Categories.ToList();
        <span style="color: rgb(215, 58, 73);">return</span> View();
    }

    <span style="color: rgb(106, 115, 125);">// 子カテゴリ取得API (AJAX用)</span>
    [<span style="color: rgb(0, 92, 197);">HttpGet</span>]
    <span style="color: rgb(215, 58, 73);">public</span> IActionResult <span style="color: rgb(111, 66, 193);">GetSubCategories</span>(<span style="color: rgb(227, 98, 9);">int</span> categoryId)
    {
        <span style="color: rgb(215, 58, 73);">var</span> subCategories = _context.SubCategories
            .Where(sc =&gt; sc.CategoryId == categoryId)
            .Select(sc =&gt; <span style="color: rgb(215, 58, 73);">new</span> { sc.Id, sc.Name })
            .ToList();

        <span style="color: rgb(215, 58, 73);">return</span> Json(subCategories);
    }
}
</code></pre><h2 data-bm="61" 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. View (Razor)</h2><pre data-priority="2" data-bm="62" 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="71" 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(248, 244, 241);"><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(60, 81, 180);">Cshtml</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(217, 223, 251); border: 1px solid rgba(0, 0, 0, 0); display: grid; grid-auto-flow: column; align-items: center; cursor: pointer; color: rgb(60, 81, 180) !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;">@{
    ViewData[&quot;Title&quot;] = &quot;2階層セレクト&quot;;
}

&lt;h2&gt;商品登録&lt;/h2&gt;

&lt;form&gt;
    &lt;div&gt;
        &lt;label&gt;カテゴリ&lt;/label&gt;
        &lt;select id=&quot;CategoryId&quot; name=&quot;CategoryId&quot; class=&quot;form-control&quot;&gt;
            &lt;option value=&quot;&quot;&gt;-- 選択してください --&lt;/option&gt;
            @foreach (var cat in ViewBag.Categories)
            {
                &lt;option value=&quot;@cat.Id&quot;&gt;@cat.Name&lt;/option&gt;
            }
        &lt;/select&gt;
    &lt;/div&gt;

    &lt;div&gt;
        &lt;label&gt;サブカテゴリ&lt;/label&gt;
        &lt;select id=&quot;SubCategoryId&quot; name=&quot;SubCategoryId&quot; class=&quot;form-control&quot;&gt;
            &lt;option value=&quot;&quot;&gt;-- 先にカテゴリを選択 --&lt;/option&gt;
        &lt;/select&gt;
    &lt;/div&gt;
&lt;/form&gt;

@section Scripts {
&lt;script src=&quot;https://code.jquery.com/jquery-3.6.0.min.js&quot;&gt;&lt;/script&gt;
&lt;script&gt;
    $(function () {
        $(&#39;#CategoryId&#39;).change(function () {
            var categoryId = $(this).val();
            var subCategorySelect = $(&#39;#SubCategoryId&#39;);
            subCategorySelect.empty();

            if (categoryId) {
                $.getJSON(&#39;/Product/GetSubCategories&#39;, { categoryId: categoryId }, function (data) {
                    subCategorySelect.append($(&#39;&lt;option&gt;&#39;).text(&#39;-- 選択してください --&#39;).attr(&#39;value&#39;, &#39;&#39;));
                    $.each(data, function (i, item) {
                        subCategorySelect.append($(&#39;&lt;option&gt;&#39;).text(item.name).attr(&#39;value&#39;, item.id));
                    });
                });
            } else {
                subCategorySelect.append($(&#39;&lt;option&gt;&#39;).text(&#39;-- 先にカテゴリを選択 --&#39;).attr(&#39;value&#39;, &#39;&#39;));
            }
        });
    });
&lt;/script&gt;
}
</code></pre><h2 data-bm="63" 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. 実装ポイント</h2><ul data-bm="64" 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;">親セレクト</strong>は初期表示時に&nbsp;<code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">ViewBag</code> で全件取得。</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;">子セレクト</strong>は親の選択変更イベントで&nbsp;<strong style="font-weight: 700;">AJAX</strong> により取得。</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;">Controller の&nbsp;<code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">GetSubCategories</code> は JSON を返すだけにして軽量化。</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;">jQuery を使わずに&nbsp;<code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">fetch</code> API でも実装可能。</li></ul><p data-bm="65" 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;">✅ この方法なら、</p><ul data-bm="66" 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;">ページリロードなしで子セレクトが切り替わる</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;">データベースの内容に応じて動的に選択肢が変わる</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;">親子関係が増えても拡張しやすい</li></ul><p data-bm="67" 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;">もし希望があれば、このコードを&nbsp;<strong style="font-weight: 700;">jQueryなしの純JavaScript版</strong> に書き換えた実装もできますが、</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>

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