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<p class='location'>Module value</p><div class="sidebar-elems"><div class="block items"><ul><li><a href="#reexports">Re-exports</a></li><li><a href="#structs">Structs</a></li><li><a href="#enums">Enums</a></li><li><a href="#traits">Traits</a></li><li><a href="#functions">Functions</a></li></ul></div><p class='location'><a href='../index.html'>serde_json</a></p><script>window.sidebarCurrent = {name: 'value', ty: 'mod', relpath: '../'};</script><script defer src="../sidebar-items.js"></script></div>
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<h1 class='fqn'><span class='in-band'>Module <a href='../index.html'>serde_json</a>::<wbr><a class="mod" href=''>value</a></span><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>]
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</span><a class='srclink' href='../../src/serde_json/value/mod.rs.html#9-1126' title='goto source code'>[src]</a></span></h1>
<div class='docblock'><p>The Value enum, a loosely typed way of representing any valid JSON value.</p>
<h1 id="constructing-json" class="section-header"><a href="#constructing-json">Constructing JSON</a></h1>
<p>Serde JSON provides a <a href="https://docs.serde.rs/serde_json/macro.json.html"><code>json!</code> macro</a> to build <code>serde_json::Value</code>
objects with very natural JSON syntax. In order to use this macro,
<code>serde_json</code> needs to be imported with the <code>#[macro_use]</code> attribute.</p>
<pre class="rust rust-example-rendered">
<span class="attribute">#[<span class="ident">macro_use</span>]</span>
<span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">serde_json</span>;
<span class="kw">fn</span> <span class="ident">main</span>() {
<span class="comment">// The type of `john` is `serde_json::Value`</span>
<span class="kw">let</span> <span class="ident">john</span> <span class="op">=</span> <span class="macro">json</span><span class="macro">!</span>({
<span class="string">&quot;name&quot;</span>: <span class="string">&quot;John Doe&quot;</span>,
<span class="string">&quot;age&quot;</span>: <span class="number">43</span>,
<span class="string">&quot;phones&quot;</span>: [
<span class="string">&quot;+44 1234567&quot;</span>,
<span class="string">&quot;+44 2345678&quot;</span>
]
});
<span class="macro">println</span><span class="macro">!</span>(<span class="string">&quot;first phone number: {}&quot;</span>, <span class="ident">john</span>[<span class="string">&quot;phones&quot;</span>][<span class="number">0</span>]);
<span class="comment">// Convert to a string of JSON and print it out</span>
<span class="macro">println</span><span class="macro">!</span>(<span class="string">&quot;{}&quot;</span>, <span class="ident">john</span>.<span class="ident">to_string</span>());
}</pre>
<p>The <code>Value::to_string()</code> function converts a <code>serde_json::Value</code> into a
<code>String</code> of JSON text.</p>
<p>One neat thing about the <code>json!</code> macro is that variables and expressions can
be interpolated directly into the JSON value as you are building it. Serde
will check at compile time that the value you are interpolating is able to
be represented as JSON.</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">full_name</span> <span class="op">=</span> <span class="string">&quot;John Doe&quot;</span>;
<span class="kw">let</span> <span class="ident">age_last_year</span> <span class="op">=</span> <span class="number">42</span>;
<span class="comment">// The type of `john` is `serde_json::Value`</span>
<span class="kw">let</span> <span class="ident">john</span> <span class="op">=</span> <span class="macro">json</span><span class="macro">!</span>({
<span class="string">&quot;name&quot;</span>: <span class="ident">full_name</span>,
<span class="string">&quot;age&quot;</span>: <span class="ident">age_last_year</span> <span class="op">+</span> <span class="number">1</span>,
<span class="string">&quot;phones&quot;</span>: [
<span class="macro">format</span><span class="macro">!</span>(<span class="string">&quot;+44 {}&quot;</span>, <span class="ident">random_phone</span>())
]
});</pre>
<p>A string of JSON data can be parsed into a <code>serde_json::Value</code> by the
<a href="https://docs.serde.rs/serde_json/de/fn.from_str.html"><code>serde_json::from_str</code></a> function. There is also
<a href="https://docs.serde.rs/serde_json/de/fn.from_slice.html"><code>from_slice</code></a> for parsing from a byte slice &amp;[u8] and
<a href="https://docs.serde.rs/serde_json/de/fn.from_reader.html"><code>from_reader</code></a> for parsing from any <code>io::Read</code> like a File or
a TCP stream.</p>
<pre class="rust rust-example-rendered">
<span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">serde_json</span>;
<span class="kw">use</span> <span class="ident">serde_json</span>::{<span class="ident">Value</span>, <span class="ident">Error</span>};
<span class="kw">fn</span> <span class="ident">untyped_example</span>() <span class="op">-&gt;</span> <span class="prelude-ty">Result</span><span class="op">&lt;</span>(), <span class="ident">Error</span><span class="op">&gt;</span> {
<span class="comment">// Some JSON input data as a &amp;str. Maybe this comes from the user.</span>
<span class="kw">let</span> <span class="ident">data</span> <span class="op">=</span> <span class="string">r#&quot;{
&quot;name&quot;: &quot;John Doe&quot;,
&quot;age&quot;: 43,
&quot;phones&quot;: [
&quot;+44 1234567&quot;,
&quot;+44 2345678&quot;
]
}&quot;#</span>;
<span class="comment">// Parse the string of data into serde_json::Value.</span>
<span class="kw">let</span> <span class="ident">v</span>: <span class="ident">Value</span> <span class="op">=</span> <span class="ident">serde_json</span>::<span class="ident">from_str</span>(<span class="ident">data</span>)<span class="question-mark">?</span>;
<span class="comment">// Access parts of the data by indexing with square brackets.</span>
<span class="macro">println</span><span class="macro">!</span>(<span class="string">&quot;Please call {} at the number {}&quot;</span>, <span class="ident">v</span>[<span class="string">&quot;name&quot;</span>], <span class="ident">v</span>[<span class="string">&quot;phones&quot;</span>][<span class="number">0</span>]);
<span class="prelude-val">Ok</span>(())
}</pre>
</div><h2 id='reexports' class='section-header'><a href="#reexports">Re-exports</a></h2>
<table><tr><td><code>pub use map::<a class="struct" href="../../serde_json/map/struct.Map.html" title="struct serde_json::map::Map">Map</a>;</code></td></tr></table><h2 id='structs' class='section-header'><a href="#structs">Structs</a></h2>
<table>
<tr class=' module-item'>
<td><a class="struct" href="struct.Number.html"
title='struct serde_json::value::Number'>Number</a></td>
<td class='docblock-short'>
<p>Represents a JSON number, whether integer or floating point.</p>
</td>
</tr></table><h2 id='enums' class='section-header'><a href="#enums">Enums</a></h2>
<table>
<tr class=' module-item'>
<td><a class="enum" href="enum.Value.html"
title='enum serde_json::value::Value'>Value</a></td>
<td class='docblock-short'>
<p>Represents any valid JSON value.</p>
</td>
</tr></table><h2 id='traits' class='section-header'><a href="#traits">Traits</a></h2>
<table>
<tr class=' module-item'>
<td><a class="trait" href="trait.Index.html"
title='trait serde_json::value::Index'>Index</a></td>
<td class='docblock-short'>
<p>A type that can be used to index into a <code>serde_json::Value</code>.</p>
</td>
</tr></table><h2 id='functions' class='section-header'><a href="#functions">Functions</a></h2>
<table>
<tr class=' module-item'>
<td><a class="fn" href="fn.from_value.html"
title='fn serde_json::value::from_value'>from_value</a></td>
<td class='docblock-short'>
<p>Interpret a <code>serde_json::Value</code> as an instance of type <code>T</code>.</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class="fn" href="fn.to_value.html"
title='fn serde_json::value::to_value'>to_value</a></td>
<td class='docblock-short'>
<p>Convert a <code>T</code> into <code>serde_json::Value</code> which is an enum that can represent
any valid JSON data.</p>
</td>
</tr></table></section>
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