wasmer/rustdoc/serde_json/fn.from_str.html

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<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="API documentation for the Rust `from_str` fn in crate `serde_json`."><meta name="keywords" content="rust, rustlang, rust-lang, from_str"><title>serde_json::from_str - Rust</title><link rel="stylesheet" type="text/css" href="../normalize.css"><link rel="stylesheet" type="text/css" href="../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../dark.css"><link rel="stylesheet" type="text/css" href="../light.css" id="themeStyle"><script src="../storage.js"></script><noscript><link rel="stylesheet" href="../noscript.css"></noscript><link rel="shortcut icon" href="../favicon.ico"><style type="text/css">#crate-search{background-image:url("../down-arrow.svg");}</style></head><body class="rustdoc fn"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">&#9776;</div><a href='../serde_json/index.html'><div class='logo-container'><img src='../rust-logo.png' alt='logo'></div></a><div class="sidebar-elems"><p class='location'><a href='index.html'>serde_json</a></p><script>window.sidebarCurrent = {name: 'from_str', ty: 'fn', relpath: ''};</script><script defer src="sidebar-items.js"></script></div></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../theme.js"></script><nav class="sub"><form class="search-form js-only"><div class="search-container"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press S to search, ? for more options…" type="search"></div><a id="settings-menu" href="../settings.html"><img src="../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class='fqn'><span class='out-of-band'><span id='render-detail'><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class='inner'>&#x2212;</span>]</a></span><a class='srclink' href='../src/serde_json/de.rs.html#2329-2334' title='goto source code'>[src]</a></span><span class='in-band'>Function <a href='index.html'>serde_json</a>::<wbr><a class="fn" href=''>from_str</a></span></h1><pre class='rust fn'>pub fn from_str&lt;'a, T&gt;(s: &amp;'a <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.str.html">str</a>) -&gt; <a class="type" href="../serde_json/type.Result.html" title="type serde_json::Result">Result</a>&lt;T&gt; <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;T: <a class="trait" href="../serde/de/trait.Deserialize.html" title="trait serde::de::Deserialize">Deserialize</a>&lt;'a&gt;,&nbsp;</span></pre><div class='docblock'><p>Deserialize an instance of type <code>T</code> from a string of JSON text.</p>
<h1 id="example" class="section-header"><a href="#example">Example</a></h1>
<div class='information'><div class='tooltip edition'><span class='tooltiptext'>This code runs with edition 2018</span></div></div><div class="example-wrap"><pre class="rust rust-example-rendered edition ">
<span class="kw">use</span> <span class="ident">serde</span>::<span class="ident">Deserialize</span>;
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Deserialize</span>, <span class="ident">Debug</span>)]</span>
<span class="kw">struct</span> <span class="ident">User</span> {
<span class="ident">fingerprint</span>: <span class="ident">String</span>,
<span class="ident">location</span>: <span class="ident">String</span>,
}
<span class="kw">fn</span> <span class="ident">main</span>() {
<span class="comment">// The type of `j` is `&amp;str`</span>
<span class="kw">let</span> <span class="ident">j</span> <span class="op">=</span> <span class="string">&quot;
{
\&quot;fingerprint\&quot;: \&quot;0xF9BA143B95FF6D82\&quot;,
\&quot;location\&quot;: \&quot;Menlo Park, CA\&quot;
}&quot;</span>;
<span class="kw">let</span> <span class="ident">u</span>: <span class="ident">User</span> <span class="op">=</span> <span class="ident">serde_json</span>::<span class="ident">from_str</span>(<span class="ident">j</span>).<span class="ident">unwrap</span>();
<span class="macro">println</span><span class="macro">!</span>(<span class="string">&quot;{:#?}&quot;</span>, <span class="ident">u</span>);
}</pre></div>
<h1 id="errors" class="section-header"><a href="#errors">Errors</a></h1>
<p>This conversion can fail if the structure of the input does not match the
structure expected by <code>T</code>, for example if <code>T</code> is a struct type but the input
contains something other than a JSON map. It can also fail if the structure
is correct but <code>T</code>'s implementation of <code>Deserialize</code> decides that something
is wrong with the data, for example required struct fields are missing from
the JSON map or some number is too big to fit in the expected primitive
type.</p>
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