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<ol class="chapter"><li class="chapter-item expanded "><a href="../intro.html"><strong aria-hidden="true">1.</strong> Introduction</a></li><li class="chapter-item expanded "><a href="../dyer-cli/index.html"><strong aria-hidden="true">2.</strong> Dyer-cli</a></li><li class="chapter-item expanded "><a href="../actor/index.html"><strong aria-hidden="true">3.</strong> Actor</a></li><li class="chapter-item expanded "><a href="../middleware/index.html"><strong aria-hidden="true">4.</strong> Middleware</a></li><li class="chapter-item expanded "><a href="../database/index.html" class="active"><strong aria-hidden="true">5.</strong> Pipeline & Database Intergration</a></li><li class="chapter-item expanded "><a href="../affix/index.html"><strong aria-hidden="true">6.</strong> Affix</a></li><li class="chapter-item expanded "><a href="../attr/index.html"><strong aria-hidden="true">7.</strong> Attribute</a></li><li class="chapter-item expanded "><a href="../feedback/index.html"><strong aria-hidden="true">8.</strong> Problem & Feedback</a></li></ol>
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<h1 class="menu-title">CookBook of dyer</h1>
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<h1 id="pipeline--database-intergration"><a class="header" href="#pipeline--database-intergration">Pipeline & Database Intergration</a></h1>
<p>the end of data flow, it will be consumed.
When an entity has been collected, it eventually will be sent to pipelines.
Pipeline provides way to do:</p>
<ul>
<li>cleaning/validating collected entity </li>
<li>de-duplicates </li>
<li>database storing</li>
</ul>
<h3 id="inspection-of-pipeline"><a class="header" href="#inspection-of-pipeline">Inspection of Pipeline</a></h3>
<p>Let's take a look at the simplified code of <code>Pipeline</code> before diving deeper.</p>
<pre><pre class="playground"><code class="language-rust no_run">
<span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>pub struct PipeLine<'pl, E, C> {
initializer: Option<&'pl dyn for<'a> Fn(&'a mut App<E>) -> Option<C>>,
disposer: Option<&'pl dyn for<'a> Fn(&'a mut App<E>)>,
process_entity:
Option<&'pl dyn for<'a> Fn(Vec<E>, &'a mut App<E>)>,
process_yerr: Option<
&'pl dyn for<'a> Fn(
Vec<Result<Response, MetaResponse>>,
&'a mut App<E>,
)>,
// other fields omitted
...
}
<span class="boring">}
</span></code></pre></pre>
<ul>
<li>the method <code>initializer</code> get called only once over the runtime, it returns a generic type <code>C</code> which defined by user, the generic type is usually a connection cursor to storage destination. </li>
<li>the method <code>disposer</code> get called once when the pipeline ends. </li>
<li>the method <code>process_entity</code> processes a vector of entity then consume them.</li>
<li>the method <code>process_yerr</code> processes a vector of failed response then consume them.</li>
</ul>
<h3 id="diesel-sql"><a class="header" href="#diesel-sql">Diesel Sql</a></h3>
<p><a href="https://diesel.rs">Diesel</a> is the most productive way to interact with SQL databases. It is recommanded to get around the basics of diesel <a href="https://diesel.rs/guides/getting-started"> here </a>.
A detailed example is given at <a href="https://github.com/HomelyGuy/dyer/tree/master/examples/dyer-diesel">examples</a>.</p>
<h3 id="other-database"><a class="header" href="#other-database">Other Database</a></h3>
<p>Almost other databases are equipmented with rust-based driver, it is just as simple as following the documentation, implementing the necessary methods.</p>
<p>Here is an simple example for MongoDB Intergration with driver <a href="https://crates.io/crates/mongodb">mongodb</a>.</p>
<pre><pre class="playground"><code class="language-rust no_run">
<span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>pub async fn establish_connection(_app: &mut App<_>) -> Option<&'static mongodb::Client> {
static INIT: Once = Once::new();
static mut VAL: Option<mongodb::Client> = None;
unsafe {
let uri = "mongodb://127.0.0.1:27017";
INIT.call_once(|| {
VAL = Some(mongodb::Client::with_uri_str(uri).await.unwrap());
});
VAL.as_ref()
}
}
pub async fn store_item(ens: Vec<_>, _app: &mut App<_>) {
// do stuff here like validating and dropping
...
let client = establish_connection(_app).await;
client.database("database_name_here")
.collection("collection_name_here")
.insert_one(...)
.await
.unwrap();
}
// set up pipiline
let pipeline = Pipeline::builder()
.initializer(establish_connection)
.entity_mut(store_item)
.build("marker".into());
<span class="boring">}
</span></code></pre></pre>
<p>This pipeline will insert collected entity into MongoDB.</p>
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