refactor: create readJsonFileAsAstObject utility

Author: alan-agius4

packages/schematics/angular/migrations/update-9/ivy-libraries.ts

@@ -5,7 +5,6 @@
  * 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 { JsonParseMode, parseJsonAst } from '@angular-devkit/core';
 import { Rule, Tree } from '@angular-devkit/schematics';
 import { getWorkspacePath } from '../../utility/config';
 import {
@@ -14,7 +13,7 @@ import {
   insertPropertyInAstObjectInOrder,
 } from '../../utility/json-utils';
 import { Builders } from '../../utility/workspace-models';
-import { getTargets, getWorkspace } from './utils';
+import { getTargets, getWorkspace, readJsonFileAsAstObject } from './utils';
 
 /**
  * Updates a pre version 9 library to version 9 Ivy library.
@@ -62,17 +61,7 @@ export function updateLibraries(): Rule {
       }
 
       // tsConfig for production already exists.
-      const tsConfigContent = tree.read(tsConfigOption.value);
-      if (!tsConfigContent) {
-        continue;
-      }
-
-      const tsConfigAst = parseJsonAst(tsConfigContent.toString(), JsonParseMode.Loose);
-      if (!tsConfigAst || tsConfigAst.kind !== 'object') {
-        // Invalid tsConfig
-        continue;
-      }
-
+      const tsConfigAst = readJsonFileAsAstObject(tree, tsConfigOption.value);
       const tsConfigRecorder = tree.beginUpdate(tsConfigOption.value);
       const ngCompilerOptions = findPropertyInAstObject(tsConfigAst, 'angularCompilerOptions');
       if (!ngCompilerOptions) {

packages/schematics/angular/migrations/update-9/ngsw-config.ts

@@ -5,11 +5,10 @@
  * 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 { JsonParseMode, parseJsonAst } from '@angular-devkit/core';
-import { Rule, SchematicsException, Tree } from '@angular-devkit/schematics';
+import { Rule,  Tree } from '@angular-devkit/schematics';
 import { appendValueInAstArray, findPropertyInAstObject } from '../../utility/json-utils';
 import { Builders } from '../../utility/workspace-models';
-import { getAllOptions, getTargets, getWorkspace } from './utils';
+import { getAllOptions, getTargets, getWorkspace, readJsonFileAsAstObject } from './utils';
 
 
 /**
@@ -27,13 +26,7 @@ export function updateNGSWConfig(): Rule {
         }
 
         const path = ngswConfigPath.value;
-        const configBuffer = tree.read(path);
-        if (!configBuffer) {
-          throw new SchematicsException(`Could not find (${path})`);
-        }
-
-        const content = configBuffer.toString();
-        const ngswConfigAst = parseJsonAst(content, JsonParseMode.Loose);
+        const ngswConfigAst = readJsonFileAsAstObject(tree, path);
         if (!ngswConfigAst || ngswConfigAst.kind !== 'object') {
           continue;
         }

packages/schematics/angular/migrations/update-9/update-app-tsconfigs.ts

@@ -5,15 +5,15 @@
  * 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 { JsonAstObject, JsonParseMode, parseJsonAst } from '@angular-devkit/core';
+import { JsonAstObject } from '@angular-devkit/core';
 import { Rule, Tree, UpdateRecorder } from '@angular-devkit/schematics';
 import {
   findPropertyInAstObject,
   insertPropertyInAstObjectInOrder,
   removePropertyInAstObject,
 } from '../../utility/json-utils';
 import { Builders } from '../../utility/workspace-models';
-import { getAllOptions, getTargets, getWorkspace } from './utils';
+import { getAllOptions, getTargets, getWorkspace, readJsonFileAsAstObject } from './utils';
 
 
 /**
@@ -52,7 +52,7 @@ function updateTsConfig(tree: Tree, builderConfig: JsonAstObject, builderName: B
     }
 
     const tsConfigPath = tsConfigOption.value;
-    let tsConfigAst = getTsConfigAst(tree, tsConfigPath);
+    let tsConfigAst = readJsonFileAsAstObject(tree, tsConfigPath);
     if (!tsConfigAst) {
       continue;
     }
@@ -77,7 +77,7 @@ function updateTsConfig(tree: Tree, builderConfig: JsonAstObject, builderName: B
     if (builderName !== Builders.Karma) {
       // Note: we need to re-read the tsconfig after very commit because
       // otherwise the updates will be out of sync since we are ammending the same node.
-      tsConfigAst = getTsConfigAst(tree, tsConfigPath) as JsonAstObject;
+      tsConfigAst = readJsonFileAsAstObject(tree, tsConfigPath);
       const files = findPropertyInAstObject(tsConfigAst, 'files');
       const include = findPropertyInAstObject(tsConfigAst, 'include');
 
@@ -93,32 +93,17 @@ function updateTsConfig(tree: Tree, builderConfig: JsonAstObject, builderName: B
         tree.commitUpdate(recorder);
 
         if (builderName === Builders.Browser) {
-          tsConfigAst = getTsConfigAst(tree, tsConfigPath) as JsonAstObject;
+          tsConfigAst = readJsonFileAsAstObject(tree, tsConfigPath);
           recorder = tree.beginUpdate(tsConfigPath);
           insertPropertyInAstObjectInOrder(recorder, tsConfigAst, 'include', [`${rootSrc}**/*.d.ts`], 2);
           tree.commitUpdate(recorder);
         }
 
-        tsConfigAst = getTsConfigAst(tree, tsConfigPath) as JsonAstObject;
+        tsConfigAst = readJsonFileAsAstObject(tree, tsConfigPath);
         recorder = tree.beginUpdate(tsConfigPath);
         removePropertyInAstObject(recorder, tsConfigAst, 'exclude');
         tree.commitUpdate(recorder);
       }
     }
   }
 }
-
-function getTsConfigAst(tree: Tree, path: string): JsonAstObject | undefined {
-  const configBuffer = tree.read(path);
-  if (!configBuffer) {
-    return undefined;
-  }
-
-  const content = configBuffer.toString();
-  const tsConfigAst = parseJsonAst(content, JsonParseMode.Loose);
-  if (!tsConfigAst || tsConfigAst.kind !== 'object') {
-    return undefined;
-  }
-
-  return tsConfigAst;
-}

packages/schematics/angular/migrations/update-9/utils.ts

@@ -72,14 +72,23 @@ export function getAllOptions(builderConfig: JsonAstObject, configurationsOnly =
 
 export function getWorkspace(host: Tree): JsonAstObject {
   const path = getWorkspacePath(host);
+
+  return readJsonFileAsAstObject(host, path);
+}
+
+export function readJsonFileAsAstObject(host: Tree, path: string): JsonAstObject {
   const configBuffer = host.read(path);
   if (!configBuffer) {
     throw new SchematicsException(`Could not find (${path})`);
   }
 
   const content = configBuffer.toString();
+  const astContent = parseJsonAst(content, JsonParseMode.Loose);
+  if (!astContent || astContent.kind !== 'object') {
+    throw new SchematicsException(`Invalid JSON AST Object (${path})`);
+  }
 
-  return parseJsonAst(content, JsonParseMode.Loose) as JsonAstObject;
+  return astContent;
 }
 
 export function isIvyEnabled(tree: Tree, tsConfigPath: string): boolean {