refactor(@schematics/angular): use Tree's newly introduced readText and readJSON functionality

Code related to decoding buffers into strings and parsing content into JSON can now be removed by using the
support provided directly from the Tree instance for the executing schematic.

Author: clydin

packages/angular_devkit/schematics_cli/blank/factory.ts

@@ -28,13 +28,9 @@ function addSchematicToCollectionJson(
   description: JsonObject,
 ): Rule {
   return (tree: Tree) => {
-    const collectionJsonContent = tree.read(collectionPath);
-    if (!collectionJsonContent) {
-      throw new Error('Invalid collection path: ' + collectionPath);
-    }
+    const collectionJson = tree.readJson(collectionPath);
 
-    const collectionJson = JSON.parse(collectionJsonContent.toString());
-    if (!isJsonObject(collectionJson.schematics)) {
+    if (!isJsonObject(collectionJson) || !isJsonObject(collectionJson.schematics)) {
       throw new Error('Invalid collection.json; schematics needs to be an object.');
     }
 
@@ -55,16 +51,13 @@ export default function (options: Schema): Rule {
 
     let collectionPath: Path | undefined;
     try {
-      const packageJsonContent = tree.read('/package.json');
-      if (packageJsonContent) {
-        const packageJson = JSON.parse(packageJsonContent.toString()) as {
-          schematics: unknown;
-        };
-        if (typeof packageJson.schematics === 'string') {
-          const p = normalize(packageJson.schematics);
-          if (tree.exists(p)) {
-            collectionPath = p;
-          }
+      const packageJson = tree.readJson('/package.json') as {
+        schematics: unknown;
+      };
+      if (typeof packageJson.schematics === 'string') {
+        const p = normalize(packageJson.schematics);
+        if (tree.exists(p)) {
+          collectionPath = p;
         }
       }
     } catch {}

packages/schematics/angular/app-shell/index.ts

@@ -35,11 +35,7 @@ import { BrowserBuilderOptions, Builders, ServerBuilderOptions } from '../utilit
 import { Schema as AppShellOptions } from './schema';
 
 function getSourceFile(host: Tree, path: string): ts.SourceFile {
-  const buffer = host.read(path);
-  if (!buffer) {
-    throw new SchematicsException(`Could not find ${path}.`);
-  }
-  const content = buffer.toString();
+  const content = host.readText(path);
   const source = ts.createSourceFile(path, content, ts.ScriptTarget.Latest, true);
 
   return source;
@@ -82,10 +78,9 @@ function getComponentTemplate(host: Tree, compPath: string, tmplInfo: TemplateIn
     const templateUrl = (tmplInfo.templateUrlProp.initializer as ts.StringLiteral).text;
     const dir = dirname(normalize(compPath));
     const templatePath = join(dir, templateUrl);
-    const buffer = host.read(templatePath);
-    if (buffer) {
-      template = buffer.toString();
-    }
+    try {
+      template = host.readText(templatePath);
+    } catch {}
   }
 
   return template;

packages/schematics/angular/component/index.ts

@@ -32,11 +32,7 @@ import { buildDefaultPath, getWorkspace } from '../utility/workspace';
 import { Schema as ComponentOptions, Style } from './schema';
 
 function readIntoSourceFile(host: Tree, modulePath: string): ts.SourceFile {
-  const text = host.read(modulePath);
-  if (text === null) {
-    throw new SchematicsException(`File ${modulePath} does not exist.`);
-  }
-  const sourceText = text.toString('utf-8');
+  const sourceText = host.readText(modulePath);
 
   return ts.createSourceFile(modulePath, sourceText, ts.ScriptTarget.Latest, true);
 }

packages/schematics/angular/directive/index.ts

@@ -36,11 +36,7 @@ function addDeclarationToNgModule(options: DirectiveOptions): Rule {
     }
 
     const modulePath = options.module;
-    const text = host.read(modulePath);
-    if (text === null) {
-      throw new SchematicsException(`File ${modulePath} does not exist.`);
-    }
-    const sourceText = text.toString('utf-8');
+    const sourceText = host.readText(modulePath);
     const source = ts.createSourceFile(modulePath, sourceText, ts.ScriptTarget.Latest, true);
 
     const directivePath =
@@ -66,11 +62,7 @@ function addDeclarationToNgModule(options: DirectiveOptions): Rule {
 
     if (options.export) {
       // Need to refresh the AST because we overwrote the file in the host.
-      const text = host.read(modulePath);
-      if (text === null) {
-        throw new SchematicsException(`File ${modulePath} does not exist.`);
-      }
-      const sourceText = text.toString('utf-8');
+      const sourceText = host.readText(modulePath);
       const source = ts.createSourceFile(modulePath, sourceText, ts.ScriptTarget.Latest, true);
 
       const exportRecorder = host.beginUpdate(modulePath);

packages/schematics/angular/module/index.ts

@@ -55,11 +55,7 @@ function addDeclarationToNgModule(options: ModuleOptions): Rule {
 
     const modulePath = options.module;
 
-    const text = host.read(modulePath);
-    if (text === null) {
-      throw new SchematicsException(`File ${modulePath} does not exist.`);
-    }
-    const sourceText = text.toString();
+    const sourceText = host.readText(modulePath);
     const source = ts.createSourceFile(modulePath, sourceText, ts.ScriptTarget.Latest, true);
 
     const relativePath = buildRelativeModulePath(options, modulePath);
@@ -101,12 +97,8 @@ function addRouteDeclarationToNgModule(
       path = options.module;
     }
 
-    const text = host.read(path);
-    if (!text) {
-      throw new Error(`Couldn't find the module nor its routing module.`);
-    }
+    const sourceText = host.readText(path);
 
-    const sourceText = text.toString();
     const addDeclaration = addRouteDeclarationToModule(
       ts.createSourceFile(path, sourceText, ts.ScriptTarget.Latest, true),
       path,

packages/schematics/angular/pipe/index.ts

@@ -35,11 +35,7 @@ function addDeclarationToNgModule(options: PipeOptions): Rule {
     }
 
     const modulePath = options.module;
-    const text = host.read(modulePath);
-    if (text === null) {
-      throw new SchematicsException(`File ${modulePath} does not exist.`);
-    }
-    const sourceText = text.toString('utf-8');
+    const sourceText = host.readText(modulePath);
     const source = ts.createSourceFile(modulePath, sourceText, ts.ScriptTarget.Latest, true);
 
     const pipePath =
@@ -63,11 +59,7 @@ function addDeclarationToNgModule(options: PipeOptions): Rule {
     host.commitUpdate(recorder);
 
     if (options.export) {
-      const text = host.read(modulePath);
-      if (text === null) {
-        throw new SchematicsException(`File ${modulePath} does not exist.`);
-      }
-      const sourceText = text.toString('utf-8');
+      const sourceText = host.readText(modulePath);
       const source = ts.createSourceFile(modulePath, sourceText, ts.ScriptTarget.Latest, true);
 
       const exportRecorder = host.beginUpdate(modulePath);

packages/schematics/angular/service-worker/index.ts

@@ -122,11 +122,7 @@ function updateAppModule(mainPath: string): Rule {
 }
 
 function getTsSourceFile(host: Tree, path: string): ts.SourceFile {
-  const buffer = host.read(path);
-  if (!buffer) {
-    throw new SchematicsException(`Could not read file (${path}).`);
-  }
-  const content = buffer.toString();
+  const content = host.readText(path);
   const source = ts.createSourceFile(path, content, ts.ScriptTarget.Latest, true);
 
   return source;

packages/schematics/angular/universal/index.ts

@@ -99,12 +99,7 @@ function updateConfigFile(options: UniversalOptions, tsConfigDirectory: Path): R
 }
 
 function findBrowserModuleImport(host: Tree, modulePath: string): ts.Node {
-  const moduleBuffer = host.read(modulePath);
-  if (!moduleBuffer) {
-    throw new SchematicsException(`Module file (${modulePath}) not found`);
-  }
-  const moduleFileText = moduleBuffer.toString('utf-8');
-
+  const moduleFileText = host.readText(modulePath);
   const source = ts.createSourceFile(modulePath, moduleFileText, ts.ScriptTarget.Latest, true);
 
   const decoratorMetadata = getDecoratorMetadata(source, 'NgModule', '@angular/core')[0];

packages/schematics/angular/utility/json-file.ts

@@ -27,12 +27,7 @@ export class JSONFile {
   content: string;
 
   constructor(private readonly host: Tree, private readonly path: string) {
-    const buffer = this.host.read(this.path);
-    if (buffer) {
-      this.content = buffer.toString();
-    } else {
-      throw new Error(`Could not read '${path}'.`);
-    }
+    this.content = this.host.readText(this.path);
   }
 
   private _jsonAst: Node | undefined;

packages/schematics/angular/utility/ng-ast-utils.ts

@@ -13,11 +13,7 @@ import * as ts from '../third_party/github.com/Microsoft/TypeScript/lib/typescri
 import { findNode, getSourceNodes } from '../utility/ast-utils';
 
 export function findBootstrapModuleCall(host: Tree, mainPath: string): ts.CallExpression | null {
-  const mainBuffer = host.read(mainPath);
-  if (!mainBuffer) {
-    throw new SchematicsException(`Main file (${mainPath}) not found`);
-  }
-  const mainText = mainBuffer.toString('utf-8');
+  const mainText = host.readText(mainPath);
   const source = ts.createSourceFile(mainPath, mainText, ts.ScriptTarget.Latest, true);
 
   const allNodes = getSourceNodes(source);
@@ -58,11 +54,7 @@ export function findBootstrapModulePath(host: Tree, mainPath: string): string {
 
   const bootstrapModule = bootstrapCall.arguments[0];
 
-  const mainBuffer = host.read(mainPath);
-  if (!mainBuffer) {
-    throw new SchematicsException(`Client application main file (${mainPath}) not found`);
-  }
-  const mainText = mainBuffer.toString('utf-8');
+  const mainText = host.readText(mainPath);
   const source = ts.createSourceFile(mainPath, mainText, ts.ScriptTarget.Latest, true);
   const allNodes = getSourceNodes(source);
   const bootstrapModuleRelativePath = allNodes

packages/schematics/angular/utility/workspace.ts

@@ -6,19 +6,14 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import { json, virtualFs, workspaces } from '@angular-devkit/core';
+import { json, workspaces } from '@angular-devkit/core';
 import { Rule, Tree, noop } from '@angular-devkit/schematics';
 import { ProjectType } from './workspace-models';
 
 function createHost(tree: Tree): workspaces.WorkspaceHost {
   return {
     async readFile(path: string): Promise<string> {
-      const data = tree.read(path);
-      if (!data) {
-        throw new Error('File not found.');
-      }
-
-      return virtualFs.fileBufferToString(data);
+      return tree.readText(path);
     },
     async writeFile(path: string, data: string): Promise<void> {
       return tree.overwrite(path, data);

packages/schematics/angular/web-worker/index.ts

@@ -65,7 +65,7 @@ function addSnippet(options: WebWorkerOptions): Rule {
     `;
 
     // Append the worker creation snippet.
-    const originalContent = host.read(siblingModulePath);
+    const originalContent = host.readText(siblingModulePath);
     host.overwrite(siblingModulePath, originalContent + '\n' + workerCreationSnippet);
 
     return host;