| <!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="Returned from `Serializer::serialize_map`."><meta name="keywords" content="rust, rustlang, rust-lang, SerializeMap"><title>SerializeMap in serde::ser - Rust</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Semibold.ttf.woff2"><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="../../ayu.css" disabled><link rel="stylesheet" type="text/css" href="../../dark.css" disabled><link rel="stylesheet" type="text/css" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script src="../../crates.js"></script><script defer src="../../main.js"></script> |
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| </a><h2 class="location">Trait SerializeMap</h2><div class="sidebar-elems"><div class="block items"><h3 class="sidebar-title"><a href="#associated-types">Associated Types</a></h3><div class="sidebar-links"><a href="#associatedtype.Error">Error</a><a href="#associatedtype.Ok">Ok</a></div><h3 class="sidebar-title"><a href="#required-methods">Required Methods</a></h3><div class="sidebar-links"><a href="#tymethod.end">end</a><a href="#tymethod.serialize_key">serialize_key</a><a href="#tymethod.serialize_value">serialize_value</a></div><h3 class="sidebar-title"><a href="#provided-methods">Provided Methods</a></h3><div class="sidebar-links"><a href="#method.serialize_entry">serialize_entry</a></div><h3 class="sidebar-title"><a href="#implementors">Implementors</a></h3></div><h2 class="location">Other items in<br><a href="../index.html">serde</a>::<wbr><a href="index.html">ser</a></h2><div id="sidebar-vars" data-name="SerializeMap" data-ty="trait" data-relpath=""></div><script defer src="sidebar-items.js"></script></div></nav><main><div class="width-limiter"><div class="sub-container"><a class="sub-logo-container" href="../../serde/index.html"><img class="rust-logo" src="../../rust-logo.png" alt="logo"></a><nav class="sub"><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!" aria-haspopup="menu" title="themes"><img width="18" height="18" alt="Pick another theme!" src="../../brush.svg"></button><div id="theme-choices" role="menu"></div></div><form class="search-form"><div class="search-container"><div> |
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| <h1 class="fqn"><span class="in-band">Trait <a href="../index.html">serde</a>::<wbr><a href="index.html">ser</a>::<wbr><a class="trait" href="#">SerializeMap</a><button id="copy-path" onclick="copy_path(this)" title="Copy item path to clipboard"><img src="../../clipboard.svg" width="19" height="18" alt="Copy item path"></button></span></h1><span class="out-of-band"> |
| <a class="srclink" href="../../src/serde/ser/mod.rs.html#1791-1850" title="goto source code">source</a> · |
| <a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span></div> |
| <div class="docblock item-decl"><pre class="rust trait"><code>pub trait SerializeMap { |
| type <a href="#associatedtype.Ok" class="associatedtype">Ok</a>; |
| type <a href="#associatedtype.Error" class="associatedtype">Error</a>: <a class="trait" href="trait.Error.html" title="trait serde::ser::Error">Error</a>; |
| fn <a href="#tymethod.serialize_key" class="fnname">serialize_key</a><T: ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>>(&mut self, key: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&</a>T) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, Self::<a class="associatedtype" href="trait.SerializeMap.html#associatedtype.Error" title="type serde::ser::SerializeMap::Error">Error</a>><br> <span class="where">where<br> T: <a class="trait" href="../trait.Serialize.html" title="trait serde::Serialize">Serialize</a></span>; |
| <div class="item-spacer"></div> fn <a href="#tymethod.serialize_value" class="fnname">serialize_value</a><T: ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>>(<br> &mut self, <br> value: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&</a>T<br> ) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, Self::<a class="associatedtype" href="trait.SerializeMap.html#associatedtype.Error" title="type serde::ser::SerializeMap::Error">Error</a>><br> <span class="where">where<br> T: <a class="trait" href="../trait.Serialize.html" title="trait serde::Serialize">Serialize</a></span>; |
| <div class="item-spacer"></div> fn <a href="#tymethod.end" class="fnname">end</a>(self) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><Self::<a class="associatedtype" href="trait.SerializeMap.html#associatedtype.Ok" title="type serde::ser::SerializeMap::Ok">Ok</a>, Self::<a class="associatedtype" href="trait.SerializeMap.html#associatedtype.Error" title="type serde::ser::SerializeMap::Error">Error</a>>; |
| |
| fn <a href="#method.serialize_entry" class="fnname">serialize_entry</a><K: ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>, V: ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>>(<br> &mut self, <br> key: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&</a>K, <br> value: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&</a>V<br> ) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, Self::<a class="associatedtype" href="trait.SerializeMap.html#associatedtype.Error" title="type serde::ser::SerializeMap::Error">Error</a>><br> <span class="where">where<br> K: <a class="trait" href="../trait.Serialize.html" title="trait serde::Serialize">Serialize</a>,<br> V: <a class="trait" href="../trait.Serialize.html" title="trait serde::Serialize">Serialize</a></span>, |
| { ... } |
| }</code></pre></div><details class="rustdoc-toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Returned from <code>Serializer::serialize_map</code>.</p> |
| <h2 id="example-use" class="section-header"><a href="#example-use">Example use</a></h2> |
| <div class='information'><div class='tooltip edition' data-edition="2018">ⓘ</div></div><div class="example-wrap"><pre class="rust rust-example-rendered edition"><code><span class="kw">use</span> <span class="ident">serde::ser</span>::{<span class="ident">Serialize</span>, <span class="ident">Serializer</span>, <span class="ident">SerializeMap</span>}; |
| |
| <span class="kw">impl</span><span class="op"><</span><span class="ident">K</span>, <span class="ident">V</span><span class="op">></span> <span class="ident">Serialize</span> <span class="kw">for</span> <span class="ident">HashMap</span><span class="op"><</span><span class="ident">K</span>, <span class="ident">V</span><span class="op">></span> |
| <span class="kw">where</span> |
| <span class="ident">K</span>: <span class="ident">Serialize</span>, |
| <span class="ident">V</span>: <span class="ident">Serialize</span>, |
| { |
| <span class="kw">fn</span> <span class="ident">serialize</span><span class="op"><</span><span class="ident">S</span><span class="op">></span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">serializer</span>: <span class="ident">S</span>) -> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">S::Ok</span>, <span class="ident">S::Error</span><span class="op">></span> |
| <span class="kw">where</span> |
| <span class="ident">S</span>: <span class="ident">Serializer</span>, |
| { |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">serializer</span>.<span class="ident">serialize_map</span>(<span class="prelude-val">Some</span>(<span class="self">self</span>.<span class="ident">len</span>()))<span class="question-mark">?</span>; |
| <span class="kw">for</span> (<span class="ident">k</span>, <span class="ident">v</span>) <span class="kw">in</span> <span class="self">self</span> { |
| <span class="ident">map</span>.<span class="ident">serialize_entry</span>(<span class="ident">k</span>, <span class="ident">v</span>)<span class="question-mark">?</span>; |
| } |
| <span class="ident">map</span>.<span class="ident">end</span>() |
| } |
| }</code></pre></div> |
| <h2 id="example-implementation" class="section-header"><a href="#example-implementation">Example implementation</a></h2> |
| <p>The <a href="https://serde.rs/data-format.html">example data format</a> presented on the website demonstrates an |
| implementation of <code>SerializeMap</code> for a basic JSON data format.</p> |
| </div></details><h2 id="associated-types" class="small-section-header">Associated Types<a href="#associated-types" class="anchor"></a></h2><div class="methods"><details class="rustdoc-toggle" open><summary><div id="associatedtype.Ok" class="method has-srclink"><div class="rightside"><a class="srclink" href="../../src/serde/ser/mod.rs.html#1793" title="goto source code">source</a></div><h4 class="code-header">type <a href="#associatedtype.Ok" class="associatedtype">Ok</a></h4></div></summary><div class="docblock"><p>Must match the <code>Ok</code> type of our <code>Serializer</code>.</p> |
| </div></details><details class="rustdoc-toggle" open><summary><div id="associatedtype.Error" class="method has-srclink"><div class="rightside"><a class="srclink" href="../../src/serde/ser/mod.rs.html#1796" title="goto source code">source</a></div><h4 class="code-header">type <a href="#associatedtype.Error" class="associatedtype">Error</a>: <a class="trait" href="trait.Error.html" title="trait serde::ser::Error">Error</a></h4></div></summary><div class="docblock"><p>Must match the <code>Error</code> type of our <code>Serializer</code>.</p> |
| </div></details></div><h2 id="required-methods" class="small-section-header">Required methods<a href="#required-methods" class="anchor"></a></h2><div class="methods"><details class="rustdoc-toggle" open><summary><div id="tymethod.serialize_key" class="method has-srclink"><div class="rightside"><a class="srclink" href="../../src/serde/ser/mod.rs.html#1804-1806" title="goto source code">source</a></div><h4 class="code-header">fn <a href="#tymethod.serialize_key" class="fnname">serialize_key</a><T: ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>>(&mut self, key: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&</a>T) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, Self::<a class="associatedtype" href="trait.SerializeMap.html#associatedtype.Error" title="type serde::ser::SerializeMap::Error">Error</a>> <span class="where fmt-newline">where<br> T: <a class="trait" href="../trait.Serialize.html" title="trait serde::Serialize">Serialize</a>, </span></h4></div></summary><div class="docblock"><p>Serialize a map key.</p> |
| <p>If possible, <code>Serialize</code> implementations are encouraged to use |
| <code>serialize_entry</code> instead as it may be implemented more efficiently in |
| some formats compared to a pair of calls to <code>serialize_key</code> and |
| <code>serialize_value</code>.</p> |
| </div></details><details class="rustdoc-toggle" open><summary><div id="tymethod.serialize_value" class="method has-srclink"><div class="rightside"><a class="srclink" href="../../src/serde/ser/mod.rs.html#1814-1816" title="goto source code">source</a></div><h4 class="code-header">fn <a href="#tymethod.serialize_value" class="fnname">serialize_value</a><T: ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>>(&mut self, value: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&</a>T) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, Self::<a class="associatedtype" href="trait.SerializeMap.html#associatedtype.Error" title="type serde::ser::SerializeMap::Error">Error</a>> <span class="where fmt-newline">where<br> T: <a class="trait" href="../trait.Serialize.html" title="trait serde::Serialize">Serialize</a>, </span></h4></div></summary><div class="docblock"><p>Serialize a map value.</p> |
| <h5 id="panics" class="section-header"><a href="#panics">Panics</a></h5> |
| <p>Calling <code>serialize_value</code> before <code>serialize_key</code> is incorrect and is |
| allowed to panic or produce bogus results.</p> |
| </div></details><details class="rustdoc-toggle" open><summary><div id="tymethod.end" class="method has-srclink"><div class="rightside"><a class="srclink" href="../../src/serde/ser/mod.rs.html#1849" title="goto source code">source</a></div><h4 class="code-header">fn <a href="#tymethod.end" class="fnname">end</a>(self) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><Self::<a class="associatedtype" href="trait.SerializeMap.html#associatedtype.Ok" title="type serde::ser::SerializeMap::Ok">Ok</a>, Self::<a class="associatedtype" href="trait.SerializeMap.html#associatedtype.Error" title="type serde::ser::SerializeMap::Error">Error</a>></h4></div></summary><div class="docblock"><p>Finish serializing a map.</p> |
| </div></details></div><h2 id="provided-methods" class="small-section-header">Provided methods<a href="#provided-methods" class="anchor"></a></h2><div class="methods"><details class="rustdoc-toggle" open><summary><div id="method.serialize_entry" class="method has-srclink"><div class="rightside"><a class="srclink" href="../../src/serde/ser/mod.rs.html#1835-1846" title="goto source code">source</a></div><h4 class="code-header">fn <a href="#method.serialize_entry" class="fnname">serialize_entry</a><K: ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>, V: ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>>(<br> &mut self, <br> key: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&</a>K, <br> value: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&</a>V<br>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, Self::<a class="associatedtype" href="trait.SerializeMap.html#associatedtype.Error" title="type serde::ser::SerializeMap::Error">Error</a>> <span class="where fmt-newline">where<br> K: <a class="trait" href="../trait.Serialize.html" title="trait serde::Serialize">Serialize</a>,<br> V: <a class="trait" href="../trait.Serialize.html" title="trait serde::Serialize">Serialize</a>, </span></h4></div></summary><div class="docblock"><p>Serialize a map entry consisting of a key and a value.</p> |
| <p>Some <a href="../trait.Serialize.html"><code>Serialize</code></a> types are not able to hold a key and value in memory |
| at the same time so <code>SerializeMap</code> implementations are required to |
| support <a href="#tymethod.serialize_key"><code>serialize_key</code></a> and <a href="#tymethod.serialize_value"><code>serialize_value</code></a> individually. The |
| <code>serialize_entry</code> method allows serializers to optimize for the case |
| where key and value are both available. <a href="../trait.Serialize.html"><code>Serialize</code></a> implementations |
| are encouraged to use <code>serialize_entry</code> if possible.</p> |
| <p>The default implementation delegates to <a href="#tymethod.serialize_key"><code>serialize_key</code></a> and |
| <a href="#tymethod.serialize_value"><code>serialize_value</code></a>. This is appropriate for serializers that do not |
| care about performance or are not able to optimize <code>serialize_entry</code> any |
| better than this.</p> |
| </div></details></div><h2 id="implementors" class="small-section-header">Implementors<a href="#implementors" class="anchor"></a></h2><div class="item-list" id="implementors-list"><details class="rustdoc-toggle implementors-toggle"><summary><div id="impl-SerializeMap" class="impl has-srclink"><div class="rightside"><a class="srclink" href="../../src/serde/ser/impossible.rs.html#148-174" title="goto source code">source</a></div><a href="#impl-SerializeMap" class="anchor"></a><h3 class="code-header in-band">impl<Ok, Error> <a class="trait" href="trait.SerializeMap.html" title="trait serde::ser::SerializeMap">SerializeMap</a> for <a class="struct" href="struct.Impossible.html" title="struct serde::ser::Impossible">Impossible</a><Ok, Error> <span class="where fmt-newline">where<br> Error: <a class="trait" href="trait.Error.html" title="trait serde::ser::Error">Error</a>, </span></h3></div></summary><div class="impl-items"><div id="associatedtype.Ok-1" class="type trait-impl has-srclink"><a href="#associatedtype.Ok-1" class="anchor"></a><h4 class="code-header">type <a href="#associatedtype.Ok" class="associatedtype">Ok</a> = Ok</h4></div><div id="associatedtype.Error-1" class="type trait-impl has-srclink"><a href="#associatedtype.Error-1" class="anchor"></a><h4 class="code-header">type <a href="#associatedtype.Error" class="associatedtype">Error</a> = Error</h4></div></div></details></div><script type="text/javascript" src="../../implementors/serde/ser/trait.SerializeMap.js" async></script></section><section id="search" class="content hidden"></section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="serde" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.60.0-nightly (1bd4fdc94 2022-01-12)" ></div> |
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