feat: accept a factory function as feed parameter

If only one feed should be generated, an object can be passed as well now

README.md

@@ -96,7 +96,52 @@ Feed creation is based on the [feed](https://github.com/jpmonette/feed) package.
 Please use it as reference and further documentation for modifying the `feed` object
 that is passed to the `create` function.
 
-Using the `create` function gives you unlimited possibilities to customize your feed!
+Using the `create` function gives you almost unlimited possibilities to customize your feed!
+
+### Using a feed factory function
+
+There is one more thing. Imagine you want to add a feed per blog category, but you don't want
+to add every category by hand.
+
+You can use a `factory function` to solve that problem. Instead of a hardcoded array, you can setup
+a function that will be called up on feed generation. The function **must** return an array with all
+feeds you want to generate.
+
+```js
+{
+ feed: async () => {
+     const posts = (await axios.get('https://my-url.com/posts')).data
+     const tags = (await axios.get('https://my-url.com/tags')).data
+
+     return tags.map(t => {
+       const relevantPosts = posts.filter(/*filter posts somehow*/)
+
+       return {
+         path: `/${t.slug}.xml`, // The route to your feed.
+         async create (feed) {
+           feed.options = {
+             title: `${t.name} - My blog`,
+             description: `All posts related to ${t.name} of my blog`,
+           }
+
+           relevantPosts.forEach(post => {
+             feed.addItem({
+               title: post.title,
+               id: post.id,
+               link: `https://blog.lichter.io/posts/${post.slug}`,
+               description: post.excerpt,
+               content: post.text
+             })
+           })
+         },
+         cacheTime: 1000 * 60 * 15,
+         type: 'rss2'
+       }
+     })
+   },
+}
+```
+
 
 ## Development
 

lib/module.js

@@ -13,8 +13,16 @@ const defaults = {
   cacheTime: 1000 * 60 * 15
 }
 
-module.exports = async function feed (moduleOptions) {
-  const options = Object.assign([], this.options.feed, moduleOptions).map(o => Object.assign({}, defaults, o))
+module.exports = async function feed () {
+  if (typeof this.options.feed === 'function') {
+    this.options.feed = await this.options.feed()
+  }
+
+  if (!Array.isArray(this.options.feed)) {
+    this.options.feed = [this.options.feed]
+  }
+
+  const options = Object.assign([], this.options.feed).map(o => Object.assign({}, defaults, o))
 
   const feedCache = new AsyncCache({
     maxAge: options.cacheTime,

test/fixture/configs/function_rss.js

@@ -0,0 +1,36 @@
+const { resolve } = require('path')
+
+module.exports = {
+  rootDir: resolve(__dirname, '../../../'),
+  srcDir: resolve(__dirname, '../'),
+  dev: false,
+  render: {
+    resourceHints: false
+  },
+  modules: ['@@'],
+  feed: () => ({
+    create (feed) {
+      feed.options = {
+        title: 'Feed Title',
+        description: 'This is my personal feed!',
+        id: 'http://example.com/',
+        link: 'http://example.com/',
+        image: 'http://example.com/image.png',
+        favicon: 'http://example.com/favicon.ico',
+        updated: new Date(2000, 6, 14), // optional, default = today
+        copyright: 'All rights reserved 2013, John Doe',
+        generator: 'awesome', // optional, default = 'Feed for Node.js'
+        feedLinks: {
+          json: 'https://example.com/json',
+          atom: 'https://example.com/atom'
+        },
+        author: {
+          name: 'John Doe',
+          email: 'johndoe@example.com',
+          link: 'https://example.com/johndoe'
+        }
+      }
+    },
+    type: 'rss2'
+  })
+}

test/fixture/configs/object_rss.js

@@ -0,0 +1,36 @@
+const { resolve } = require('path')
+
+module.exports = {
+  rootDir: resolve(__dirname, '../../../'),
+  srcDir: resolve(__dirname, '../'),
+  dev: false,
+  render: {
+    resourceHints: false
+  },
+  modules: ['@@'],
+  feed: {
+    create (feed) {
+      feed.options = {
+        title: 'Feed Title',
+        description: 'This is my personal feed!',
+        id: 'http://example.com/',
+        link: 'http://example.com/',
+        image: 'http://example.com/image.png',
+        favicon: 'http://example.com/favicon.ico',
+        updated: new Date(2000, 6, 14), // optional, default = today
+        copyright: 'All rights reserved 2013, John Doe',
+        generator: 'awesome', // optional, default = 'Feed for Node.js'
+        feedLinks: {
+          json: 'https://example.com/json',
+          atom: 'https://example.com/atom'
+        },
+        author: {
+          name: 'John Doe',
+          email: 'johndoe@example.com',
+          link: 'https://example.com/johndoe'
+        }
+      }
+    },
+    type: 'rss2'
+  }
+}

test/module.test.js

@@ -128,6 +128,52 @@ describe('universal', () => {
     expect(await get('/feed.xml')).toBe('')
   }, timeout)
 
+  test('object rss', async () => {
+    nuxt = await setupNuxt(require('./fixture/configs/object_rss'))
+    let html = await get('/feed.xml')
+    expect(html).toBe('<?xml version="1.0" encoding="utf-8"?>\n' +
+      '<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">\n' +
+      '    <channel>\n' +
+      '        <title>Feed Title</title>\n' +
+      '        <link>http://example.com/</link>\n' +
+      '        <description>This is my personal feed!</description>\n' +
+      '        <lastBuildDate>' + date.rss + '</lastBuildDate>\n' +
+      '        <docs>http://blogs.law.harvard.edu/tech/rss</docs>\n' +
+      '        <generator>awesome</generator>\n' +
+      '        <image>\n' +
+      '            <title>Feed Title</title>\n' +
+      '            <url>http://example.com/image.png</url>\n' +
+      '            <link>http://example.com/</link>\n' +
+      '        </image>\n' +
+      '        <copyright>All rights reserved 2013, John Doe</copyright>\n' +
+      '        <atom:link href="https://example.com/atom" rel="self" type="application/rss+xml"/>\n' +
+      '    </channel>\n' +
+      '</rss>')
+  }, timeout)
+
+  test('function rss', async () => {
+    nuxt = await setupNuxt(require('./fixture/configs/function_rss'))
+    let html = await get('/feed.xml')
+    expect(html).toBe('<?xml version="1.0" encoding="utf-8"?>\n' +
+      '<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">\n' +
+      '    <channel>\n' +
+      '        <title>Feed Title</title>\n' +
+      '        <link>http://example.com/</link>\n' +
+      '        <description>This is my personal feed!</description>\n' +
+      '        <lastBuildDate>' + date.rss + '</lastBuildDate>\n' +
+      '        <docs>http://blogs.law.harvard.edu/tech/rss</docs>\n' +
+      '        <generator>awesome</generator>\n' +
+      '        <image>\n' +
+      '            <title>Feed Title</title>\n' +
+      '            <url>http://example.com/image.png</url>\n' +
+      '            <link>http://example.com/</link>\n' +
+      '        </image>\n' +
+      '        <copyright>All rights reserved 2013, John Doe</copyright>\n' +
+      '        <atom:link href="https://example.com/atom" rel="self" type="application/rss+xml"/>\n' +
+      '    </channel>\n' +
+      '</rss>')
+  }, timeout)
+
   test('multi rss', async () => {
     nuxt = await setupNuxt(require('./fixture/configs/multi_rss'))