fix(@angular/cli): Show detailed help for generate

Fixes #7723

Author: Brocco

packages/@angular/cli/commands/generate.ts

@@ -17,7 +17,7 @@ import { SchematicAvailableOptions } from '../tasks/schematic-get-options';
 const Command = require('../ember-cli/lib/models/command');
 const SilentError = require('silent-error');
 
-const { cyan, yellow } = chalk;
+const { cyan, grey, yellow } = chalk;
 const separatorRegEx = /[\/\\]/g;
 
 
@@ -186,15 +186,57 @@ export default Command.extend({
       });
   },
 
-  printDetailedHelp: function () {
+  printDetailedHelp: function (_options: any, rawArgs: any): string | Promise<string> {
     const engineHost = getEngineHost();
     const collectionName = this.getCollectionName();
     const collection = getCollection(collectionName);
-    const schematicNames: string[] = engineHost.listSchematics(collection);
-    this.ui.writeLine(cyan('Available schematics:'));
-    schematicNames.forEach(schematicName => {
-      this.ui.writeLine(yellow(`    ${schematicName}`));
-    });
-    this.ui.writeLine('');
+    const schematicName = rawArgs[1];
+    if (schematicName) {
+      const SchematicGetOptionsTask = require('../tasks/schematic-get-options').default;
+      const getOptionsTask = new SchematicGetOptionsTask({
+        ui: this.ui,
+        project: this.project
+      });
+      return getOptionsTask.run({
+        schematicName,
+        collectionName
+      })
+      .then((availableOptions: SchematicAvailableOptions[]) => {
+        const output: string[] = [];
+        output.push(cyan(`ng generate ${schematicName} ${cyan('[name]')} ${cyan('<options...>')}`));
+        availableOptions
+          .filter(opt => opt.name !== 'name')
+          .forEach(opt => {
+            let text = cyan(`    --${opt.name}`);
+            if (opt.schematicType) {
+              text += cyan(` (${opt.schematicType})`);
+            }
+            if (opt.schematicDefault) {
+              text += cyan(` (Default: ${opt.schematicDefault})`);
+            }
+            if (opt.description) {
+              text += ` ${opt.description}`;
+            }
+            output.push(text);
+            if (opt.aliases && opt.aliases.length > 0) {
+              const aliasText = opt.aliases.reduce(
+                (acc, curr) => {
+                  return acc + ` -${curr}`;
+                },
+                '');
+              output.push(grey(`      aliases: ${aliasText}`));
+            }
+          });
+        return output.join('\n');
+      });
+    } else {
+      const schematicNames: string[] = engineHost.listSchematics(collection);
+      const output: string[] = [];
+      output.push(cyan('Available schematics:'));
+      schematicNames.forEach(schematicName => {
+        output.push(yellow(`    ${schematicName}`));
+      });
+      return Promise.resolve(output.join('\n'));
+    }
   }
 });

packages/@angular/cli/commands/help.ts

@@ -66,8 +66,13 @@ const HelpCommand = Command.extend({
         if (cmd === commandInput) {
           if (commandOptions.short) {
             this.ui.writeLine(command.printShortHelp(commandOptions));
-          } else if (command.printDetailedHelp(commandOptions)) {
-            this.ui.writeLine(command.printDetailedHelp(commandOptions));
+          } else if (command.printDetailedHelp(commandOptions, rawArgs)) {
+            const result = command.printDetailedHelp(commandOptions, rawArgs);
+            if (result instanceof Promise) {
+              result.then(r => this.ui.writeLine(r));
+            } else {
+              this.ui.writeLine(result);
+            }
           } else {
             this.ui.writeLine(command.printBasicHelp(commandOptions));
           }

packages/@angular/cli/tasks/schematic-get-options.ts

@@ -13,6 +13,8 @@ export interface SchematicAvailableOptions {
   description: string;
   aliases: string[];
   type: any;
+  schematicType: any;
+  schematicDefault: any;
 }
 
 export default Task.extend({
@@ -30,6 +32,7 @@ export default Task.extend({
       .map(key => ({...properties[key], ...{name: stringUtils.dasherize(key)}}))
       .map(opt => {
         let type;
+        const schematicType = opt.type;
         switch (opt.type) {
           case 'string':
             type = String;
@@ -54,11 +57,15 @@ export default Task.extend({
           aliases = [...aliases, ...opt.aliases];
         }
 
+        const schematicDefault = opt.default;
+
         return {
           ...opt,
           aliases,
           type,
-          default: undefined // do not carry over schematics defaults
+          schematicType,
+          default: undefined, // do not carry over schematics defaults
+          schematicDefault
         };
       })
       .filter(x => x);