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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"><strong aria-hidden="true">5.</strong> Pipeline & Database Intergration</a></li><li class="chapter-item expanded "><a href="../affix/index.html" class="active"><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="affix"><a class="header" href="#affix">Affix</a></h1>
<p>Affix is the fringerprint when making a request. In general, affix is not necessay unless the target site requires visitor meet some criteria. Affix, by far, mainly focus on modification of Headers.</p>
<blockquote>
<p>assign a user-agent for each Task with file <code>user-agents.txt</code> containing user-agents by lines</p>
</blockquote>
<pre><pre class="playground"><code class="language-rust no_run">
<span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>// src/affix.rs
pub struct Aff {
uas: Vec<String>
iter: std::iter::Cycle<String>,
}
#[dyer::async_trait]
impl Affixor for Aff {
// this function only runs once
async fn init(&mut self) {
use std::io::Read;
let mut file = std::fs::File::open("path/to/user-agents.txt").unwrap();
let buf = std::io::BufReader::new(file);
let uas = buf.lines().map(|line| {
line.unwrap()
}).collect::<Vec<String>>();
self.uas = uas;
self.iter = self.uas.iter().cycle();
}
// if the affix isn't obtained via network(request-response), just return `None`
async fn invoke(&mut self) -> Option<dyer::Request> {
None
}
// dyer combine the `Affix` returned by this function to each `Task` before make an request
async fn parse(&mut self, _: Option<Result<Response, MetaResponse>>) -> Option<dyer::Affix> {
// return the user-agent in order
self.iter.next().to_owned()
}
// other method of Affixor
...
}
// src/actor.rs
#[dyer::async_trait]
impl Actor<_, _> for MyActor {
async fn entry_affix(&mut self) -> Option<Aff> {
Some(Aff)
}
// other method of Actor
...
}
<span class="boring">}
</span></code></pre></pre>
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