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| 20 | <div class="body page-extensions_example">
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| 22 | <div class="right"><a href="https://github.com/rstacruz/scour" data-title="rstacruz/scour" class="iconlink">
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| 23 | <span class="icon -github"></span></a>
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| 25 | </div>
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| 26 | <div class="markdown-body"><h1 id="extensions-example">Extensions example</h1>
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| 27 | <p>Here’s a simple data set which would be common with data that comes from SQL
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| 28 | sources. Notice that it has foreign key relations in it: objects in <code>albums</code>
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| 29 | have the <code>artist_id</code> property that maps to the ID’s in <code>artists</code>.</p>
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| 30 | <h5 class="file-heading" id="sample-data">Sample data</h5>
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| 31 | <pre><code class="lang-js">data =
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| 32 | { artists:
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| 33 | { <span class="hljs-number">1</span>: { id: <span class="hljs-number">1</span>, name: <span class="pl-s">'Ella Fitzgerald'</span> },
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| 34 | <span class="hljs-number">2</span>: { id: <span class="hljs-number">2</span>, name: <span class="pl-s">'Frank Sinatra'</span> },
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| 35 | <span class="hljs-number">3</span>: { id: <span class="hljs-number">3</span>, name: <span class="pl-s">'Miles Davis'</span> },
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| 36 | <span class="hljs-number">4</span>: { id: <span class="hljs-number">4</span>, name: <span class="pl-s">'Taylor Swift'</span> } },
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| 37 | albums:
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| 38 | { <span class="hljs-number">1</span>: { id: <span class="hljs-number">1</span>, name: <span class="pl-s">'Kind of Blue'</span>, genre: <span class="pl-s">'Jazz'</span>, artist_id: <span class="hljs-number">3</span> },
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| 39 | <span class="hljs-number">2</span>: { id: <span class="hljs-number">2</span>, name: <span class="pl-s">'Come Fly With Me'</span>, genre: <span class="pl-s">'Jazz'</span>, artist_id: <span class="hljs-number">2</span> },
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| 40 | <span class="hljs-number">3</span>: { id: <span class="hljs-number">3</span>, name: <span class="pl-s">'1984'</span>, genre: <span class="pl-s">'Pop'</span>, artist_id: <span class="hljs-number">4</span> } } }
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| 41 | </code></pre>
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| 42 | <h2 id="defining-extensions">Defining extensions</h2>
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| 43 | <p>You can define extensions to traverse this intelligently, like ActiveRecord.
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| 44 | Here, we’ll use <a href="index.html#use">use()</a> to define extra methods that will
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| 45 | be applied to certain keypaths.</p>
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| 46 | <h5 class="file-heading" id="models">Models</h5>
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| 47 | <pre><code class="lang-js">Root = {
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| 48 | artists () { <span class="pl-k">return</span> <span class="pl-k">this</span>.go(<span class="pl-s">'artists'</span>) },
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| 49 | albums () { <span class="pl-k">return</span> <span class="pl-k">this</span>.go(<span class="pl-s">'albums'</span>) }
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| 50 | }
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| 51 |
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| 52 | Artist = {
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| 53 | <span class="pl-c">// Defines a has-many relationship</span>
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| 54 | albums () {
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| 55 | <span class="pl-k">return</span> <span class="pl-k">this</span>.root.albums().filter({ artist_id: <span class="pl-k">this</span>.get(<span class="pl-s">'id'</span>) })
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| 56 | }
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| 57 | }
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| 58 |
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| 59 | Album = {
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| 60 | <span class="pl-c">// Defines a belongs-to relationship</span>
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| 61 | artist () {
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| 62 | <span class="pl-k">return</span> <span class="pl-k">this</span>.root.artists().go(<span class="pl-k">this</span>.get(<span class="pl-s">'artist_id'</span>))
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| 63 | }
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| 64 | }
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| 65 | </code></pre>
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| 66 | <h5 class="file-heading" id="using-with-scour">Using with scour</h5>
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| 67 | <pre><code class="lang-js">db = scour(data)
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| 68 | .use({
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| 69 | <span class="pl-s">''</span>: Root,
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| 70 | <span class="pl-s">'artists.*'</span>: Artist,
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| 71 | <span class="pl-s">'albums.*'</span>: Album
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| 72 | })
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| 73 | </code></pre>
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| 74 | <h2 id="root-extensions">Root extensions</h2>
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| 75 | <p>With the extensions to the root (<code>''</code>), it defined an alias to <code>go('albums')</code>
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| 76 | as <code>albums()</code>.</p>
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| 77 | <pre><code class="lang-js">albums = db.albums().filter({ genre: <span class="pl-s">'Jazz'</span> })
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| 78 | </code></pre>
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| 79 | <h2 id="traversing-relationships">Traversing relationships</h2>
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| 80 | <p>Combined with the extensions to <code>artists.*</code> and <code>albums.*</code>, we can use it to
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| 81 | traverse back-and-forth along “models”.</p>
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| 82 | <h5 class="file-heading" id="chaining-example">Chaining example</h5>
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| 83 | <pre><code class="lang-js">db
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| 84 | .artists()
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| 85 | .find({ name: <span class="pl-s">'Taylor Swift'</span> })
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| 86 | .albums()
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| 87 | </code></pre>
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| 88 | <h5 class="file-heading" id="another-example">Another example</h5>
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| 89 | <pre><code class="lang-js">albums.each((album) => {
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| 90 | <span class="pl-c1">console</span>.log(album.artist().get(<span class="pl-s">'name'</span>))
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| 91 | })
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| 92 | </code></pre>
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| 93 |
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| 112 | <ul class="headings heading-list">
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| 113 | <li class="heading-item -depth-2"><a href="#defining-extensions" class="hlink link-defining-extensions">Defining extensions</a>
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| 114 | </li>
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| 115 | <li class="heading-item -depth-2"><a href="#root-extensions" class="hlink link-root-extensions">Root extensions</a>
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| 116 | </li>
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| 117 | <li class="heading-item -depth-2"><a href="#traversing-relationships" class="hlink link-traversing-relationships">Traversing relationships</a>
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| 118 | </li>
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| 119 | </ul>
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