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ジャンルのカテゴリ―名

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内容の要旨

<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: 700 22px / 24px Roboto, Helvetica, sans-serif; height: 28px; -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;" data-pasted="true">コードの意味</h2><pre data-priority="2" data-bm="64" style="background: none 0% 0% / auto repeat scroll padding-box border-box rgb(245, 245, 245); border-color: rgba(0, 0, 0, 0.1); border-style: solid; border-width: 1px; border-image: none 100% / 1 / 0 stretch; 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="75" 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(240, 243, 255);"><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: inherit; font-variant: inherit; font-weight: 700; font-stretch: inherit; line-height: 18px; font-family: inherit; font-optical-sizing: inherit; font-size-adjust: inherit; font-kerning: inherit; font-feature-settings: inherit; font-variation-settings: inherit; 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-color: rgba(0, 0, 0, 0); border-style: solid; border-width: 1px; border-image: none 100% / 1 / 0 stretch; display: grid; grid-auto-flow: column; align-items: center; gap: 4px; cursor: pointer; color: rgb(60, 81, 180) !important; text-decoration: none !important; border-radius: 9999px; padding-block: 3px; padding-inline: 8px;"><div style="box-sizing: border-box; margin: 0px; padding: 0px; min-inline-size: 0px; white-space: nowrap; overflow: clip; text-overflow: ellipsis; max-block-size: calc(1lh);">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);">var</span> list = ViewBag.KamokuList <span style="color: rgb(215, 58, 73);">as</span> List&lt;Kamoku&gt;;
</code></pre><ul 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: 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;"><p style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: 8px 0px; padding: revert; -webkit-line-clamp: revert;"><code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">ViewBag.KamokuList</code><br>&rarr; Controller 側でセットされたデータ（例：科目リスト）</p></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;"><p style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: 8px 0px; padding: revert; -webkit-line-clamp: revert;"><code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">as List&lt;Kamoku&gt;</code><br>&rarr;&nbsp;<strong style="font-weight: 700;">安全な型変換</strong>（<code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">as</code> 演算子）で&nbsp;<code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">List&lt;Kamoku&gt;</code> 型に変換</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;"><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;">成功 &rarr;&nbsp;<code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">list</code> に&nbsp;<code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">List&lt;Kamoku&gt;</code> が入る</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;">失敗 &rarr;&nbsp;<code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">list</code> に&nbsp;<code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">null</code> が入る（例外は発生しない）</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;"><p style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: 8px 0px; padding: revert; -webkit-line-clamp: revert;"><code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">var list</code><br>&rarr; 変数&nbsp;<code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">list</code> の型は&nbsp;<code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">List&lt;Kamoku&gt;</code>（または&nbsp;<code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">null</code>）になる</p></li></ul><h2 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; font: 700 22px / 24px Roboto, Helvetica, sans-serif; height: 28px; -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. Controller 側の例</h2><pre data-priority="2" data-bm="67" style="background: none 0% 0% / auto repeat scroll padding-box border-box rgb(245, 245, 245); border-color: rgba(0, 0, 0, 0.1); border-style: solid; border-width: 1px; border-image: none 100% / 1 / 0 stretch; 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="76" 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(240, 243, 255);"><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: inherit; font-variant: inherit; font-weight: 700; font-stretch: inherit; line-height: 18px; font-family: inherit; font-optical-sizing: inherit; font-size-adjust: inherit; font-kerning: inherit; font-feature-settings: inherit; font-variation-settings: inherit; 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-color: rgba(0, 0, 0, 0); border-style: solid; border-width: 1px; border-image: none 100% / 1 / 0 stretch; display: grid; grid-auto-flow: column; align-items: center; gap: 4px; cursor: pointer; color: rgb(60, 81, 180) !important; text-decoration: none !important; border-radius: 9999px; padding-block: 3px; padding-inline: 8px;"><div style="box-sizing: border-box; margin: 0px; padding: 0px; min-inline-size: 0px; white-space: nowrap; overflow: clip; text-overflow: ellipsis; max-block-size: calc(1lh);">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);">public</span> ActionResult <span style="color: rgb(111, 66, 193);">Index</span>()
{
    <span style="color: rgb(215, 58, 73);">var</span> kamokuList = <span style="color: rgb(215, 58, 73);">new</span> List&lt;Kamoku&gt;
    {
        <span style="color: rgb(215, 58, 73);">new</span> Kamoku { Id = <span style="color: rgb(0, 92, 197);">1</span>, Name = <span style="color: rgb(3, 47, 98);">&quot;数学&quot;</span> },
        <span style="color: rgb(215, 58, 73);">new</span> Kamoku { Id = <span style="color: rgb(0, 92, 197);">2</span>, Name = <span style="color: rgb(3, 47, 98);">&quot;英語&quot;</span> }
    };

    ViewBag.KamokuList = kamokuList; <span style="color: rgb(106, 115, 125);">// ViewBag に格納</span>
    <span style="color: rgb(215, 58, 73);">return</span> View();
}
</code></pre><h2 data-bm="68" 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: 700 22px / 24px Roboto, Helvetica, sans-serif; height: 28px; -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 側の例（Razor）</h2><pre data-priority="2" data-bm="69" style="background: none 0% 0% / auto repeat scroll padding-box border-box rgb(245, 245, 245); border-color: rgba(0, 0, 0, 0.1); border-style: solid; border-width: 1px; border-image: none 100% / 1 / 0 stretch; 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="77" 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(240, 243, 255);"><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: inherit; font-variant: inherit; font-weight: 700; font-stretch: inherit; line-height: 18px; font-family: inherit; font-optical-sizing: inherit; font-size-adjust: inherit; font-kerning: inherit; font-feature-settings: inherit; font-variation-settings: inherit; 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-color: rgba(0, 0, 0, 0); border-style: solid; border-width: 1px; border-image: none 100% / 1 / 0 stretch; display: grid; grid-auto-flow: column; align-items: center; gap: 4px; cursor: pointer; color: rgb(60, 81, 180) !important; text-decoration: none !important; border-radius: 9999px; padding-block: 3px; padding-inline: 8px;"><div style="box-sizing: border-box; margin: 0px; padding: 0px; min-inline-size: 0px; white-space: nowrap; overflow: clip; text-overflow: ellipsis; max-block-size: calc(1lh);">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);">var</span> list = ViewBag.KamokuList <span style="color: rgb(215, 58, 73);">as</span> List&lt;Kamoku&gt;;
}

@if (list != <span style="color: rgb(0, 92, 197);">null</span>)
{
    &lt;ul&gt;
    @foreach (<span style="color: rgb(215, 58, 73);">var</span> item <span style="color: rgb(215, 58, 73);">in</span> list)
    {
        &lt;li&gt;@item.Name&lt;/li&gt;
    }
    &lt;/ul&gt;
}
<span style="color: rgb(215, 58, 73);">else</span>
{
    &lt;p&gt;科目リストがありません。&lt;/p&gt;
}
</code></pre><h2 data-bm="70" 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: 700 22px / 24px Roboto, Helvetica, sans-serif; height: 28px; -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.&nbsp;<code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">as</code> と&nbsp;<code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">(List&lt;Kamoku&gt;)</code> の違い</h2><ul data-bm="71" 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;"><code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">as</code><br>&rarr; 型変換に失敗すると&nbsp;<strong style="font-weight: 700;">null</strong> を返す（例外なし）</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;"><code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">(List&lt;Kamoku&gt;)</code><br>&rarr; 型変換に失敗すると&nbsp;<strong style="font-weight: 700;">InvalidCastException</strong> が発生</li></ul><p data-bm="72" style="border: 0px; border-collapse: collapse; border-spacing: 0px; list-style-position: initial; list-style-image: initial; list-style-type: revert; margin: 8px 0px; 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;">✅&nbsp;<strong style="font-weight: 700;">ポイント</strong></p><ul data-bm="73" 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;">ViewBag は型安全ではないため、キャスト時に&nbsp;<code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">as</code> を使うと安全</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;">ただし、<code style="border-radius: 8px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(255, 255, 255);">null</code> チェックを忘れないこと</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;">型安全にしたい場合は&nbsp;<strong style="font-weight: 700;">ViewModel</strong> を使うのがベスト</li></ul><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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