fix(compiler-ssr): add selected option attribute from select value

alex-snezhko · alex-snezhko · commit 67ad86174df5 · 2025-06-28T16:18:53.000-07:00
diff --git a/packages/compiler-ssr/__tests__/ssrElement.spec.ts b/packages/compiler-ssr/__tests__/ssrElement.spec.ts
@@ -1,5 +1,7 @@
 import { getCompiledString } from './utils'
 import { compile } from '../src'
+import { renderToString } from '@vue/server-renderer'
+import { createApp } from '@vue/runtime-dom'
 
 describe('ssr: element', () => {
   test('basic elements', () => {
@@ -71,6 +73,160 @@ describe('ssr: element', () => {
         `)
     })
 
+    test('<select> with dynamic value assigns `selected` option attribute', async () => {
+      expect(
+        getCompiledString(
+          `<select :value="selectValue"><option value="1"></option></select>`,
+        ),
+      ).toMatchInlineSnapshot(`
+        "\`<select><option value="1"\${
+            (_ssrIncludeBooleanAttr((Array.isArray(_ctx.selectValue))
+              ? _ssrLooseContain(_ctx.selectValue, "1")
+              : _ssrLooseEqual(_ctx.selectValue, "1"))) ? " selected" : ""
+          }></option></select>\`"
+      `)
+
+      expect(
+        await renderToString(
+          createApp({
+            data: () => ({ selected: 2 }),
+            template: `<div><select :value="selected"><option value="1">1</option><option value="2">2</option></select></div>`,
+          }),
+        ),
+      ).toMatchInlineSnapshot(
+        `"<div><select><option value="1">1</option><option value="2" selected>2</option></select></div>"`,
+      )
+    })
+
+    test('<select> with static value assigns `selected` option attribute', async () => {
+      expect(
+        getCompiledString(
+          `<select value="selectValue"><option value="1"></option></select>`,
+        ),
+      ).toMatchInlineSnapshot(`
+        "\`<select><option value="1"\${
+            (_ssrIncludeBooleanAttr(_ssrLooseEqual("selectValue", "1"))) ? " selected" : ""
+          }></option></select>\`"
+      `)
+
+      expect(
+        await renderToString(
+          createApp({
+            template: `<div><select value="2"><option value="1">1</option><option value="2">2</option></select></div>`,
+          }),
+        ),
+      ).toMatchInlineSnapshot(
+        `"<div><select><option value="1">1</option><option value="2" selected>2</option></select></div>"`,
+      )
+    })
+
+    test('<select> with dynamic v-bind assigns `selected` option attribute', async () => {
+      expect(
+        compile(`<select v-bind="obj"><option value="1"></option></select>`)
+          .code,
+      ).toMatchInlineSnapshot(`
+        "const { mergeProps: _mergeProps } = require("vue")
+        const { ssrRenderAttrs: _ssrRenderAttrs, ssrIncludeBooleanAttr: _ssrIncludeBooleanAttr, ssrLooseContain: _ssrLooseContain, ssrLooseEqual: _ssrLooseEqual } = require("vue/server-renderer")
+
+        return function ssrRender(_ctx, _push, _parent, _attrs) {
+          let _temp0
+
+          _push(\`<select\${
+            _ssrRenderAttrs(_temp0 = _mergeProps(_ctx.obj, _attrs))
+          }><option value="1"\${
+            (_ssrIncludeBooleanAttr(("value" in _temp0)
+              ? (Array.isArray(_temp0.value))
+                  ? _ssrLooseContain(_temp0.value, "1")
+                  : _ssrLooseEqual(_temp0.value, "1")
+              : false)) ? " selected" : ""
+          }></option></select>\`)
+        }"
+      `)
+
+      expect(
+        await renderToString(
+          createApp({
+            data: () => ({ obj: { value: 2 } }),
+            template: `<div><select v-bind="obj"><option value="1">1</option><option value="2">2</option></select></div>`,
+          }),
+        ),
+      ).toMatchInlineSnapshot(
+        `"<div><select value="2"><option value="1">1</option><option value="2" selected>2</option></select></div>"`,
+      )
+    })
+
+    test('<select> with dynamic v-bind and dynamic value bind assigns `selected` option attribute', async () => {
+      expect(
+        compile(
+          `<select v-bind="obj" :value="selectValue"><option value="1"></option></select>`,
+        ).code,
+      ).toMatchInlineSnapshot(`
+        "const { mergeProps: _mergeProps } = require("vue")
+        const { ssrRenderAttrs: _ssrRenderAttrs, ssrIncludeBooleanAttr: _ssrIncludeBooleanAttr, ssrLooseContain: _ssrLooseContain, ssrLooseEqual: _ssrLooseEqual } = require("vue/server-renderer")
+
+        return function ssrRender(_ctx, _push, _parent, _attrs) {
+          let _temp0
+
+          _push(\`<select\${
+            _ssrRenderAttrs(_temp0 = _mergeProps(_ctx.obj, { value: _ctx.selectValue }, _attrs))
+          }><option value="1"\${
+            (_ssrIncludeBooleanAttr(("value" in _temp0)
+              ? (Array.isArray(_temp0.value))
+                  ? _ssrLooseContain(_temp0.value, "1")
+                  : _ssrLooseEqual(_temp0.value, "1")
+              : false)) ? " selected" : ""
+          }></option></select>\`)
+        }"
+      `)
+
+      expect(
+        await renderToString(
+          createApp({
+            data: () => ({ obj: { value: 1 } }),
+            template: `<div><select v-bind="obj" :value="2"><option value="1">1</option><option value="2">2</option></select></div>`,
+          }),
+        ),
+      ).toMatchInlineSnapshot(
+        `"<div><select value="2"><option value="1">1</option><option value="2" selected>2</option></select></div>"`,
+      )
+    })
+
+    test('<select> with dynamic v-bind and static value bind assigns `selected` option attribute', async () => {
+      expect(
+        compile(
+          `<select v-bind="obj" value="selectValue"><option value="1"></option></select>`,
+        ).code,
+      ).toMatchInlineSnapshot(`
+        "const { mergeProps: _mergeProps } = require("vue")
+        const { ssrRenderAttrs: _ssrRenderAttrs, ssrIncludeBooleanAttr: _ssrIncludeBooleanAttr, ssrLooseContain: _ssrLooseContain, ssrLooseEqual: _ssrLooseEqual } = require("vue/server-renderer")
+
+        return function ssrRender(_ctx, _push, _parent, _attrs) {
+          let _temp0
+
+          _push(\`<select\${
+            _ssrRenderAttrs(_temp0 = _mergeProps(_ctx.obj, { value: "selectValue" }, _attrs))
+          }><option value="1"\${
+            (_ssrIncludeBooleanAttr(("value" in _temp0)
+              ? (Array.isArray(_temp0.value))
+                  ? _ssrLooseContain(_temp0.value, "1")
+                  : _ssrLooseEqual(_temp0.value, "1")
+              : false)) ? " selected" : ""
+          }></option></select>\`)
+        }"
+      `)
+
+      expect(
+        await renderToString(
+          createApp({
+            data: () => ({ obj: { value: 1 } }),
+            template: `<div><select v-bind="obj" value="2"><option value="1">1</option><option value="2">2</option></select></div>`,
+          }),
+        ),
+      ).toMatchInlineSnapshot(
+        `"<div><select value="2"><option value="1">1</option><option value="2" selected>2</option></select></div>"`,
+      )
+    })
+
     test('multiple _ssrInterpolate at parent and child import dependency once', () => {
       expect(
         compile(`<div>{{ hello }}<textarea v-bind="a"></textarea></div>`).code,
diff --git a/packages/compiler-ssr/src/transforms/ssrTransformElement.ts b/packages/compiler-ssr/src/transforms/ssrTransformElement.ts
@@ -57,6 +57,7 @@ import {
   type SSRTransformContext,
   processChildren,
 } from '../ssrCodegenTransform'
+import { processSelectChildren } from '../utils'
 
 // for directives with children overwrite (e.g. v-html & v-text), we need to
 // store the raw children so that they can be added in the 2nd pass.
@@ -139,6 +140,22 @@ export const ssrTransformElement: NodeTransform = (node, context) => {
               ]),
             )
           }
+        } else if (node.tag === 'select') {
+          // <select> with dynamic v-bind. We don't know if the final props
+          // will contain .value, so we will have to do something special:
+          // assign the merged props to a temp variable, and check whether
+          // it contains value (if yes, mark options selected).
+          const tempId = `_temp${context.temps++}`
+          propsExp.arguments = [
+            createAssignmentExpression(
+              createSimpleExpression(tempId, false),
+              mergedProps,
+            ),
+          ]
+          processSelectChildren(context, node.children, {
+            type: 'dynamicVBind',
+            tempId,
+          })
         } else if (node.tag === 'input') {
           // <input v-bind="obj" v-model>
           // we need to determine the props to render for the dynamic v-model
@@ -223,10 +240,17 @@ export const ssrTransformElement: NodeTransform = (node, context) => {
           context.onError(
             createCompilerError(ErrorCodes.X_V_SLOT_MISPLACED, prop.loc),
           )
-        } else if (isTextareaWithValue(node, prop) && prop.exp) {
+        } else if (isTagWithValueBind(node, 'textarea', prop) && prop.exp) {
           if (!needMergeProps) {
             node.children = [createInterpolation(prop.exp, prop.loc)]
           }
+        } else if (isTagWithValueBind(node, 'select', prop) && prop.exp) {
+          if (!needMergeProps) {
+            processSelectChildren(context, node.children, {
+              type: 'dynamicValue',
+              value: prop.exp,
+            })
+          }
         } else if (!needMergeProps && prop.name !== 'on') {
           // Directive transforms.
           const directiveTransform = context.directiveTransforms[prop.name]
@@ -326,6 +350,13 @@ export const ssrTransformElement: NodeTransform = (node, context) => {
         const name = prop.name
         if (node.tag === 'textarea' && name === 'value' && prop.value) {
           rawChildrenMap.set(node, escapeHtml(prop.value.content))
+        } else if (node.tag === 'select' && name === 'value' && prop.value) {
+          if (!needMergeProps) {
+            processSelectChildren(context, node.children, {
+              type: 'staticValue',
+              value: prop.value.content,
+            })
+          }
         } else if (!needMergeProps) {
           if (name === 'key' || name === 'ref') {
             continue
@@ -399,12 +430,13 @@ function isTrueFalseValue(prop: DirectiveNode | AttributeNode) {
   }
 }
 
-function isTextareaWithValue(
+function isTagWithValueBind(
   node: PlainElementNode,
+  targetTag: string,
   prop: DirectiveNode,
 ): boolean {
   return !!(
-    node.tag === 'textarea' &&
+    node.tag === targetTag &&
     prop.name === 'bind' &&
     isStaticArgOf(prop.arg, 'value')
   )
diff --git a/packages/compiler-ssr/src/transforms/ssrVModel.ts b/packages/compiler-ssr/src/transforms/ssrVModel.ts
@@ -2,27 +2,23 @@ import {
   DOMErrorCodes,
   type DirectiveTransform,
   ElementTypes,
-  type ExpressionNode,
   NodeTypes,
-  type PlainElementNode,
-  type TemplateChildNode,
   createCallExpression,
   createConditionalExpression,
   createDOMCompilerError,
   createInterpolation,
   createObjectProperty,
-  createSimpleExpression,
   findProp,
   hasDynamicKeyVBind,
   transformModel,
 } from '@vue/compiler-dom'
 import {
-  SSR_INCLUDE_BOOLEAN_ATTR,
   SSR_LOOSE_CONTAIN,
   SSR_LOOSE_EQUAL,
   SSR_RENDER_DYNAMIC_MODEL,
 } from '../runtimeHelpers'
 import type { DirectiveTransformResult } from 'packages/compiler-core/src/transform'
+import { findValueBinding, processSelectChildren } from '../utils'
 
 export const ssrTransformModel: DirectiveTransform = (dir, node, context) => {
   const model = dir.exp!
@@ -39,48 +35,6 @@ export const ssrTransformModel: DirectiveTransform = (dir, node, context) => {
     }
   }
 
-  const processSelectChildren = (children: TemplateChildNode[]) => {
-    children.forEach(child => {
-      if (child.type === NodeTypes.ELEMENT) {
-        processOption(child as PlainElementNode)
-      } else if (child.type === NodeTypes.FOR) {
-        processSelectChildren(child.children)
-      } else if (child.type === NodeTypes.IF) {
-        child.branches.forEach(b => processSelectChildren(b.children))
-      }
-    })
-  }
-
-  function processOption(plainNode: PlainElementNode) {
-    if (plainNode.tag === 'option') {
-      if (plainNode.props.findIndex(p => p.name === 'selected') === -1) {
-        const value = findValueBinding(plainNode)
-        plainNode.ssrCodegenNode!.elements.push(
-          createConditionalExpression(
-            createCallExpression(context.helper(SSR_INCLUDE_BOOLEAN_ATTR), [
-              createConditionalExpression(
-                createCallExpression(`Array.isArray`, [model]),
-                createCallExpression(context.helper(SSR_LOOSE_CONTAIN), [
-                  model,
-                  value,
-                ]),
-                createCallExpression(context.helper(SSR_LOOSE_EQUAL), [
-                  model,
-                  value,
-                ]),
-              ),
-            ]),
-            createSimpleExpression(' selected', true),
-            createSimpleExpression('', true),
-            false /* no newline */,
-          ),
-        )
-      }
-    } else if (plainNode.tag === 'optgroup') {
-      processSelectChildren(plainNode.children)
-    }
-  }
-
   if (node.tagType === ElementTypes.ELEMENT) {
     const res: DirectiveTransformResult = { props: [] }
     const defaultProps = [
@@ -173,7 +127,10 @@ export const ssrTransformModel: DirectiveTransform = (dir, node, context) => {
       checkDuplicatedValue()
       node.children = [createInterpolation(model, model.loc)]
     } else if (node.tag === 'select') {
-      processSelectChildren(node.children)
+      processSelectChildren(context, node.children, {
+        type: 'dynamicValue',
+        value: model,
+      })
     } else {
       context.onError(
         createDOMCompilerError(
@@ -189,12 +146,3 @@ export const ssrTransformModel: DirectiveTransform = (dir, node, context) => {
     return transformModel(dir, node, context)
   }
 }
-
-function findValueBinding(node: PlainElementNode): ExpressionNode {
-  const valueBinding = findProp(node, 'value')
-  return valueBinding
-    ? valueBinding.type === NodeTypes.DIRECTIVE
-      ? valueBinding.exp!
-      : createSimpleExpression(valueBinding.value!.content, true)
-    : createSimpleExpression(`null`, false)
-}
diff --git a/packages/compiler-ssr/src/utils.ts b/packages/compiler-ssr/src/utils.ts
