edlang/serde/de/trait.Error.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="The `Error` trait allows `Deserialize` implementations to create descriptive error messages belonging to the `Deserializer` against which they are currently running."><title>Error in serde::de - Rust</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-46f98efaafac5295.ttf.woff2,FiraSans-Regular-018c141bf0843ffd.woff2,FiraSans-Medium-8f9a781e4970d388.woff2,SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2,SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../../static.files/normalize-76eba96aa4d2e634.css"><link rel="stylesheet" href="../../static.files/rustdoc-dd39b87e5fcfba68.css"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="serde" data-themes="" data-resource-suffix="" data-rustdoc-version="1.80.0 (051478957 2024-07-21)" data-channel="1.80.0" data-search-js="search-d52510db62a78183.js" data-settings-js="settings-4313503d2e1961c2.js" ><script src="../../static.files/storage-118b08c4c78b968e.js"></script><script defer src="sidebar-items.js"></script><script defer src="../../static.files/main-20a3ad099b048cf2.js"></script><noscript><link rel="stylesheet" href="../../static.files/noscript-df360f571f6edeae.css"></noscript><link rel="alternate icon" type="image/png" href="../../static.files/favicon-32x32-422f7d1d52889060.png"><link rel="icon" type="image/svg+xml" href="../../static.files/favicon-2c020d218678b618.svg"></head><body class="rustdoc trait"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="mobile-topbar"><button class="sidebar-menu-toggle" title="show sidebar"></button></nav><nav class="sidebar"><div class="sidebar-crate"><h2><a href="../../serde/index.html">serde</a><span class="version">1.0.204</span></h2></div><h2 class="location"><a href="#">Error</a></h2><div class="sidebar-elems"><section><h3><a href="#required-methods">Required Methods</a></h3><ul class="block"><li><a href="#tymethod.custom">custom</a></li></ul><h3><a href="#provided-methods">Provided Methods</a></h3><ul class="block"><li><a href="#method.duplicate_field">duplicate_field</a></li><li><a href="#method.invalid_length">invalid_length</a></li><li><a href="#method.invalid_type">invalid_type</a></li><li><a href="#method.invalid_value">invalid_value</a></li><li><a href="#method.missing_field">missing_field</a></li><li><a href="#method.unknown_field">unknown_field</a></li><li><a href="#method.unknown_variant">unknown_variant</a></li></ul><h3><a href="#object-safety">Object Safety</a></h3><h3><a href="#implementors">Implementors</a></h3></section><h2><a href="index.html">In serde::de</a></h2></div></nav><div class="sidebar-resizer"></div><main><div class="width-limiter"><rustdoc-search></rustdoc-search><section id="main-content" class="content"><div class="main-heading"><h1>Trait <a href="../index.html">serde</a>::<wbr><a href="index.html">de</a>::<wbr><a class="trait" href="#">Error</a><button id="copy-path" title="Copy item path to clipboard">Copy item path</button></h1><span class="out-of-band"><a class="src" href="../../src/serde/de/mod.rs.html#301">source</a> · <button id="toggle-all-docs" title="collapse all docs">[<span>&#x2212;</span>]</button></span></div><pre class="rust item-decl"><code>pub trait Error: <a class="trait" href="https://doc.rust-lang.org/1.80.0/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a> + <a class="trait" href="https://doc.rust-lang.org/1.80.0/core/error/trait.Error.html" title="trait core::error::Error">StdError</a> {
// Required method
fn <a href="#tymethod.custom" class="fn">custom</a>&lt;T&gt;(msg: T) -&gt; Self
<span class="where">where T: <a class="trait" href="https://doc.rust-lang.org/1.80.0/core/fmt/trait.Display.html" title="trait core::fmt::Display">Display</a></span>;
// Provided methods
fn <a href="#method.invalid_type" class="fn">invalid_type</a>(unexp: <a class="enum" href="enum.Unexpected.html" title="enum serde::de::Unexpected">Unexpected</a>&lt;'_&gt;, exp: &amp;dyn <a class="trait" href="trait.Expected.html" title="trait serde::de::Expected">Expected</a>) -&gt; Self { ... }
<span class="item-spacer"></span> fn <a href="#method.invalid_value" class="fn">invalid_value</a>(unexp: <a class="enum" href="enum.Unexpected.html" title="enum serde::de::Unexpected">Unexpected</a>&lt;'_&gt;, exp: &amp;dyn <a class="trait" href="trait.Expected.html" title="trait serde::de::Expected">Expected</a>) -&gt; Self { ... }
<span class="item-spacer"></span> fn <a href="#method.invalid_length" class="fn">invalid_length</a>(len: <a class="primitive" href="https://doc.rust-lang.org/1.80.0/std/primitive.usize.html">usize</a>, exp: &amp;dyn <a class="trait" href="trait.Expected.html" title="trait serde::de::Expected">Expected</a>) -&gt; Self { ... }
<span class="item-spacer"></span> fn <a href="#method.unknown_variant" class="fn">unknown_variant</a>(variant: &amp;<a class="primitive" href="https://doc.rust-lang.org/1.80.0/std/primitive.str.html">str</a>, expected: &amp;'static [&amp;'static <a class="primitive" href="https://doc.rust-lang.org/1.80.0/std/primitive.str.html">str</a>]) -&gt; Self { ... }
<span class="item-spacer"></span> fn <a href="#method.unknown_field" class="fn">unknown_field</a>(field: &amp;<a class="primitive" href="https://doc.rust-lang.org/1.80.0/std/primitive.str.html">str</a>, expected: &amp;'static [&amp;'static <a class="primitive" href="https://doc.rust-lang.org/1.80.0/std/primitive.str.html">str</a>]) -&gt; Self { ... }
<span class="item-spacer"></span> fn <a href="#method.missing_field" class="fn">missing_field</a>(field: &amp;'static <a class="primitive" href="https://doc.rust-lang.org/1.80.0/std/primitive.str.html">str</a>) -&gt; Self { ... }
<span class="item-spacer"></span> fn <a href="#method.duplicate_field" class="fn">duplicate_field</a>(field: &amp;'static <a class="primitive" href="https://doc.rust-lang.org/1.80.0/std/primitive.str.html">str</a>) -&gt; Self { ... }
}</code></pre><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>The <code>Error</code> trait allows <code>Deserialize</code> implementations to create descriptive
error messages belonging to the <code>Deserializer</code> against which they are
currently running.</p>
<p>Every <code>Deserializer</code> declares an <code>Error</code> type that encompasses both
general-purpose deserialization errors as well as errors specific to the
particular deserialization format. For example the <code>Error</code> type of
<code>serde_json</code> can represent errors like an invalid JSON escape sequence or an
unterminated string literal, in addition to the error cases that are part of
this trait.</p>
<p>Most deserializers should only need to provide the <code>Error::custom</code> method
and inherit the default behavior for the other methods.</p>
<h2 id="example-implementation"><a class="doc-anchor" href="#example-implementation">§</a>Example implementation</h2>
<p>The <a href="https://serde.rs/data-format.html">example data format</a> presented on the website shows an error
type appropriate for a basic JSON data format.</p>
</div></details><h2 id="required-methods" class="section-header">Required Methods<a href="#required-methods" class="anchor">§</a></h2><div class="methods"><details class="toggle method-toggle" open><summary><section id="tymethod.custom" class="method"><a class="src rightside" href="../../src/serde/de/mod.rs.html#301">source</a><h4 class="code-header">fn <a href="#tymethod.custom" class="fn">custom</a>&lt;T&gt;(msg: T) -&gt; Self<div class="where">where
T: <a class="trait" href="https://doc.rust-lang.org/1.80.0/core/fmt/trait.Display.html" title="trait core::fmt::Display">Display</a>,</div></h4></section></summary><div class="docblock"><p>Raised when there is general error when deserializing a type.</p>
<p>The message should not be capitalized and should not end with a period.</p>
<div class="example-wrap edition"><a href="#" class="tooltip" title="This example runs with edition 2021"></a><pre class="rust rust-example-rendered"><code><span class="kw">use </span>serde::de::{<span class="self">self</span>, Deserialize, Deserializer};
<span class="kw">impl</span>&lt;<span class="lifetime">'de</span>&gt; Deserialize&lt;<span class="lifetime">'de</span>&gt; <span class="kw">for </span>IpAddr {
<span class="kw">fn </span>deserialize&lt;D&gt;(deserializer: D) -&gt; <span class="prelude-ty">Result</span>&lt;<span class="self">Self</span>, D::Error&gt;
<span class="kw">where
</span>D: Deserializer&lt;<span class="lifetime">'de</span>&gt;,
{
<span class="kw">let </span>s = String::deserialize(deserializer)<span class="question-mark">?</span>;
s.parse().map_err(de::Error::custom)
}
}</code></pre></div>
</div></details></div><h2 id="provided-methods" class="section-header">Provided Methods<a href="#provided-methods" class="anchor">§</a></h2><div class="methods"><details class="toggle method-toggle" open><summary><section id="method.invalid_type" class="method"><a class="src rightside" href="../../src/serde/de/mod.rs.html#301">source</a><h4 class="code-header">fn <a href="#method.invalid_type" class="fn">invalid_type</a>(unexp: <a class="enum" href="enum.Unexpected.html" title="enum serde::de::Unexpected">Unexpected</a>&lt;'_&gt;, exp: &amp;dyn <a class="trait" href="trait.Expected.html" title="trait serde::de::Expected">Expected</a>) -&gt; Self</h4></section></summary><div class="docblock"><p>Raised when a <code>Deserialize</code> receives a type different from what it was
expecting.</p>
<p>The <code>unexp</code> argument provides information about what type was received.
This is the type that was present in the input file or other source data
of the Deserializer.</p>
<p>The <code>exp</code> argument provides information about what type was being
expected. This is the type that is written in the program.</p>
<p>For example if we try to deserialize a String out of a JSON file
containing an integer, the unexpected type is the integer and the
expected type is the string.</p>
</div></details><details class="toggle method-toggle" open><summary><section id="method.invalid_value" class="method"><a class="src rightside" href="../../src/serde/de/mod.rs.html#301">source</a><h4 class="code-header">fn <a href="#method.invalid_value" class="fn">invalid_value</a>(unexp: <a class="enum" href="enum.Unexpected.html" title="enum serde::de::Unexpected">Unexpected</a>&lt;'_&gt;, exp: &amp;dyn <a class="trait" href="trait.Expected.html" title="trait serde::de::Expected">Expected</a>) -&gt; Self</h4></section></summary><div class="docblock"><p>Raised when a <code>Deserialize</code> receives a value of the right type but that
is wrong for some other reason.</p>
<p>The <code>unexp</code> argument provides information about what value was received.
This is the value that was present in the input file or other source
data of the Deserializer.</p>
<p>The <code>exp</code> argument provides information about what value was being
expected. This is the type that is written in the program.</p>
<p>For example if we try to deserialize a String out of some binary data
that is not valid UTF-8, the unexpected value is the bytes and the
expected value is a string.</p>
</div></details><details class="toggle method-toggle" open><summary><section id="method.invalid_length" class="method"><a class="src rightside" href="../../src/serde/de/mod.rs.html#301">source</a><h4 class="code-header">fn <a href="#method.invalid_length" class="fn">invalid_length</a>(len: <a class="primitive" href="https://doc.rust-lang.org/1.80.0/std/primitive.usize.html">usize</a>, exp: &amp;dyn <a class="trait" href="trait.Expected.html" title="trait serde::de::Expected">Expected</a>) -&gt; Self</h4></section></summary><div class="docblock"><p>Raised when deserializing a sequence or map and the input data contains
too many or too few elements.</p>
<p>The <code>len</code> argument is the number of elements encountered. The sequence
or map may have expected more arguments or fewer arguments.</p>
<p>The <code>exp</code> argument provides information about what data was being
expected. For example <code>exp</code> might say that a tuple of size 6 was
expected.</p>
</div></details><details class="toggle method-toggle" open><summary><section id="method.unknown_variant" class="method"><a class="src rightside" href="../../src/serde/de/mod.rs.html#301">source</a><h4 class="code-header">fn <a href="#method.unknown_variant" class="fn">unknown_variant</a>(variant: &amp;<a class="primitive" href="https://doc.rust-lang.org/1.80.0/std/primitive.str.html">str</a>, expected: &amp;'static [&amp;'static <a class="primitive" href="https://doc.rust-lang.org/1.80.0/std/primitive.str.html">str</a>]) -&gt; Self</h4></section></summary><div class="docblock"><p>Raised when a <code>Deserialize</code> enum type received a variant with an
unrecognized name.</p>
</div></details><details class="toggle method-toggle" open><summary><section id="method.unknown_field" class="method"><a class="src rightside" href="../../src/serde/de/mod.rs.html#301">source</a><h4 class="code-header">fn <a href="#method.unknown_field" class="fn">unknown_field</a>(field: &amp;<a class="primitive" href="https://doc.rust-lang.org/1.80.0/std/primitive.str.html">str</a>, expected: &amp;'static [&amp;'static <a class="primitive" href="https://doc.rust-lang.org/1.80.0/std/primitive.str.html">str</a>]) -&gt; Self</h4></section></summary><div class="docblock"><p>Raised when a <code>Deserialize</code> struct type received a field with an
unrecognized name.</p>
</div></details><details class="toggle method-toggle" open><summary><section id="method.missing_field" class="method"><a class="src rightside" href="../../src/serde/de/mod.rs.html#301">source</a><h4 class="code-header">fn <a href="#method.missing_field" class="fn">missing_field</a>(field: &amp;'static <a class="primitive" href="https://doc.rust-lang.org/1.80.0/std/primitive.str.html">str</a>) -&gt; Self</h4></section></summary><div class="docblock"><p>Raised when a <code>Deserialize</code> struct type expected to receive a required
field with a particular name but that field was not present in the
input.</p>
</div></details><details class="toggle method-toggle" open><summary><section id="method.duplicate_field" class="method"><a class="src rightside" href="../../src/serde/de/mod.rs.html#301">source</a><h4 class="code-header">fn <a href="#method.duplicate_field" class="fn">duplicate_field</a>(field: &amp;'static <a class="primitive" href="https://doc.rust-lang.org/1.80.0/std/primitive.str.html">str</a>) -&gt; Self</h4></section></summary><div class="docblock"><p>Raised when a <code>Deserialize</code> struct type received more than one of the
same field.</p>
</div></details></div><h2 id="object-safety" class="section-header">Object Safety<a href="#object-safety" class="anchor">§</a></h2><div class="object-safety-info">This trait is <b>not</b> <a href="https://doc.rust-lang.org/1.80.0/reference/items/traits.html#object-safety">object safe</a>.</div><h2 id="implementors" class="section-header">Implementors<a href="#implementors" class="anchor">§</a></h2><div id="implementors-list"><section id="impl-Error-for-Error" class="impl"><a class="src rightside" href="../../src/serde/de/value.rs.html#60-81">source</a><a href="#impl-Error-for-Error" class="anchor">§</a><h3 class="code-header">impl <a class="trait" href="trait.Error.html" title="trait serde::de::Error">Error</a> for <a class="struct" href="value/struct.Error.html" title="struct serde::de::value::Error">Error</a></h3></section></div><script src="../../trait.impl/serde/de/trait.Error.js" async></script></section></div></main></body></html>