feat(language-service): support to fix missing required inputs diagnostic (#50911)

ivanwonder · crisbeto · commit 5d2e85920e71 · 2025-06-19T10:13:26.000+02:00
Support to add the missing required inputs into the element and append after the last attribute of the element. But it skips the structural directive shorthand attribute. For example, `<a *ngFor=""></a>`, its shorthand is `<ng-template ngFor>`, the `valueSpan` of the `ngFor` is empty, and the info is lost, so it can't use to insert the missing attribute after it. PR Close #50911
diff --git a/packages/compiler-cli/src/ngtsc/typecheck/api/checker.ts b/packages/compiler-cli/src/ngtsc/typecheck/api/checker.ts
@@ -139,6 +139,10 @@ export interface TemplateTypeChecker {
    */
   getSymbolOfNode(node: TmplAstElement, component: ts.ClassDeclaration): ElementSymbol | null;
   getSymbolOfNode(node: TmplAstTemplate, component: ts.ClassDeclaration): TemplateSymbol | null;
+  getSymbolOfNode(
+    node: TmplAstTemplate | TmplAstElement,
+    component: ts.ClassDeclaration,
+  ): TemplateSymbol | ElementSymbol | null;
   getSymbolOfNode(
     node: TmplAstComponent,
     component: ts.ClassDeclaration,
diff --git a/packages/language-service/src/codefixes/all_codefixes_metas.ts b/packages/language-service/src/codefixes/all_codefixes_metas.ts
@@ -10,11 +10,13 @@ import {fixInvalidBananaInBoxMeta} from './fix_invalid_banana_in_box';
 import {missingImportMeta} from './fix_missing_import';
 import {missingMemberMeta} from './fix_missing_member';
 import {fixUnusedStandaloneImportsMeta} from './fix_unused_standalone_imports';
+import {fixMissingRequiredInput} from './fix_missing_required_inputs';
 import {CodeActionMeta} from './utils';
 
 export const ALL_CODE_FIXES_METAS: CodeActionMeta[] = [
   missingMemberMeta,
   fixInvalidBananaInBoxMeta,
   missingImportMeta,
   fixUnusedStandaloneImportsMeta,
+  fixMissingRequiredInput,
 ];
diff --git a/packages/language-service/src/codefixes/fix_missing_required_inputs.ts b/packages/language-service/src/codefixes/fix_missing_required_inputs.ts
@@ -0,0 +1,212 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {
+  BindingType,
+  TmplAstBoundAttribute,
+  TmplAstElement,
+  TmplAstNode,
+  TmplAstTemplate,
+  TmplAstTextAttribute,
+} from '@angular/compiler';
+import {ErrorCode, ngErrorCode} from '@angular/compiler-cli/src/ngtsc/diagnostics';
+import {TypeCheckableDirectiveMeta} from '@angular/compiler-cli/src/ngtsc/typecheck/api';
+import ts from 'typescript';
+
+import {getTargetAtPosition, TargetNodeKind} from '../template_target';
+
+import {CodeActionContext, CodeActionMeta, FixIdForCodeFixesAll} from './utils';
+
+/**
+ * This code action will fix the missing required input of an element.
+ */
+export const fixMissingRequiredInput: CodeActionMeta = {
+  errorCodes: [ngErrorCode(ErrorCode.MISSING_REQUIRED_INPUTS)],
+  getCodeActions: function ({typeCheckInfo, start, compiler, fileName}: CodeActionContext) {
+    if (typeCheckInfo === null) {
+      return [];
+    }
+
+    const positionDetails = getTargetAtPosition(typeCheckInfo.nodes, start);
+    if (positionDetails === null) {
+      return [];
+    }
+
+    // For two-way bindings, we actually only need to be concerned with the bound attribute because
+    // the bindings in the template are written with the attribute name, not the event name.
+    const node =
+      positionDetails.context.kind === TargetNodeKind.TwoWayBindingContext
+        ? positionDetails.context.nodes[0]
+        : positionDetails.context.node;
+
+    if (!(node instanceof TmplAstElement || node instanceof TmplAstTemplate)) {
+      return [];
+    }
+
+    let tagName: string | null = null;
+    if (node instanceof TmplAstElement) {
+      tagName = node.name;
+    } else {
+      tagName = node.tagName;
+    }
+    if (tagName === null) {
+      return [];
+    }
+
+    let insertPosition = node.startSourceSpan.start.offset + tagName.length + 1;
+    const lastAttribute = findLastAttributeInTheElement(node);
+    if (lastAttribute !== null) {
+      insertPosition = lastAttribute.sourceSpan.end.offset;
+    }
+
+    const ttc = compiler.getTemplateTypeChecker();
+
+    const symbol = ttc.getSymbolOfNode(node, typeCheckInfo.declaration);
+    if (symbol === null) {
+      return [];
+    }
+
+    const codeActions: ts.CodeFixAction[] = [];
+
+    for (const dirSymbol of symbol.directives) {
+      const directive = dirSymbol.tsSymbol.valueDeclaration;
+      if (!ts.isClassDeclaration(directive)) {
+        continue;
+      }
+
+      const meta = ttc.getDirectiveMetadata(directive);
+      if (meta === null) {
+        continue;
+      }
+
+      const seenRequiredInputs = new Set<string>();
+
+      const boundAttrs = getBoundAttributes(meta, node);
+      for (const attr of boundAttrs) {
+        for (const {fieldName, required} of attr.inputs) {
+          if (required) {
+            seenRequiredInputs.add(fieldName);
+          }
+        }
+      }
+
+      for (const input of meta.inputs) {
+        if (!input.required || seenRequiredInputs.has(input.classPropertyName)) {
+          continue;
+        }
+        const typeCheck = compiler.getCurrentProgram().getTypeChecker();
+        const memberSymbol = typeCheck.getPropertyOfType(dirSymbol.tsType, input.classPropertyName);
+        if (memberSymbol === undefined) {
+          continue;
+        }
+
+        // As a general solution, always offer a property binding suggestion (e.g., `[inputName]=""`).
+        // This is the most versatile way for users to satisfy a required input,
+        // allowing them to bind to component properties or provide initial literal values.
+        const insertBoundText = `[${input.bindingPropertyName}]=""`;
+        codeActions.push({
+          fixName: FixIdForCodeFixesAll.FIX_MISSING_REQUIRED_INPUTS,
+          // fixId: FixIdForCodeFixesAll.FIX_MISSING_REQUIRED_INPUTS,
+          // fixAllDescription: '',
+          description: `Create ${insertBoundText} attribute for "${tagName}"`,
+          changes: [
+            {
+              fileName,
+              textChanges: [
+                {
+                  span: ts.createTextSpan(insertPosition, 0),
+                  newText: ' ' + insertBoundText,
+                },
+              ],
+            },
+          ],
+        });
+      }
+    }
+
+    return codeActions;
+  },
+  fixIds: [FixIdForCodeFixesAll.FIX_MISSING_REQUIRED_INPUTS],
+  getAllCodeActions: function () {
+    return {
+      changes: [],
+    };
+  },
+};
+
+interface TcbBoundAttribute {
+  attribute: TmplAstBoundAttribute | TmplAstTextAttribute;
+  inputs: {
+    fieldName: string;
+    required: boolean;
+  }[];
+}
+
+function getBoundAttributes(
+  directive: TypeCheckableDirectiveMeta,
+  node: TmplAstTemplate | TmplAstElement,
+): TcbBoundAttribute[] {
+  const boundInputs: TcbBoundAttribute[] = [];
+
+  const processAttribute = (attr: TmplAstBoundAttribute | TmplAstTextAttribute) => {
+    // Skip non-property bindings.
+    if (attr instanceof TmplAstBoundAttribute && attr.type !== BindingType.Property) {
+      return;
+    }
+
+    // Skip the attribute if the directive does not have an input for it.
+    const inputs = directive.inputs.getByBindingPropertyName(attr.name);
+
+    if (inputs !== null) {
+      boundInputs.push({
+        attribute: attr,
+        inputs: inputs.map((input) => ({
+          fieldName: input.classPropertyName,
+          required: input.required,
+        })),
+      });
+    }
+  };
+
+  node.inputs.forEach(processAttribute);
+  node.attributes.forEach(processAttribute);
+  if (node instanceof TmplAstTemplate) {
+    node.templateAttrs.forEach(processAttribute);
+  }
+
+  return boundInputs;
+}
+
+/**
+ * If the last attribute is from the structural directive, it is skipped and returns
+ * the previous attribute.
+ */
+function findLastAttributeInTheElement(
+  element: TmplAstElement | TmplAstTemplate,
+): TmplAstNode | null {
+  let lastAttribute: TmplAstNode | null = null;
+
+  const updateAttribute = (attr: TmplAstNode) => {
+    if (lastAttribute === null) {
+      lastAttribute = attr;
+      return;
+    }
+    if (attr.sourceSpan.end.offset < lastAttribute.sourceSpan.end.offset) {
+      return;
+    }
+    lastAttribute = attr;
+  };
+
+  const attrNodes = [...element.attributes, ...element.inputs, ...element.outputs];
+
+  for (const attr of attrNodes) {
+    updateAttribute(attr);
+  }
+
+  return lastAttribute;
+}
diff --git a/packages/language-service/src/codefixes/utils.ts b/packages/language-service/src/codefixes/utils.ts
@@ -138,4 +138,5 @@ export enum FixIdForCodeFixesAll {
   FIX_INVALID_BANANA_IN_BOX = 'fixInvalidBananaInBox',
   FIX_MISSING_IMPORT = 'fixMissingImport',
   FIX_UNUSED_STANDALONE_IMPORTS = 'fixUnusedStandaloneImports',
+  FIX_MISSING_REQUIRED_INPUTS = 'fixMissingRequiredInputs',
 }
diff --git a/packages/language-service/test/code_fixes_spec.ts b/packages/language-service/test/code_fixes_spec.ts

Original file line number	Diff line number	Diff line change
`@@ -138,4 +138,5 @@ export enum FixIdForCodeFixesAll {`
`138`	`138`	`FIX_INVALID_BANANA_IN_BOX = 'fixInvalidBananaInBox',`
`139`	`139`	`FIX_MISSING_IMPORT = 'fixMissingImport',`
`140`	`140`	`FIX_UNUSED_STANDALONE_IMPORTS = 'fixUnusedStandaloneImports',`
	`141`	`+ FIX_MISSING_REQUIRED_INPUTS = 'fixMissingRequiredInputs',`
`141`	`142`	`}`