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<h2 id="系列导航">系列导航</h2>! _/ y" y9 f9 t6 n0 Z. V
<p><a href="https://www.cnblogs.com/code4nothing/p/graphql-net6-0.html">使用Hot Chocolate和.NET 6构建GraphQL应用文章索引</a></p>( `! t% z- P! L% v/ `/ J
<h2 id="需求">需求</h2>& G1 G/ a, I5 \4 R" ~
<p>在讨论完GraphQL中的查询需求后,这篇文章我们将演示如何实现GraphQL中的数据添加任务。</p>
9 [, q5 r4 P/ S- X, a* e. Q<h2 id="思路">思路</h2>8 t T* Z* d+ v$ h5 h2 P
<p>在GraphQL中,对数据进行查询使用<code>query</code>,而对于修改数据则需要使用<code>mutation</code>,包括新增和修改数据。Hot Chocolate在使用Mutation的逻辑上和使用Query的基本一致,但是需要根据需要定义用于创建或者更新的数据对象,所以我们直接进行实现。</p>8 b2 e, p* a- j7 W0 `' `& ^5 D
<h2 id="实现">实现</h2>
" P7 W6 G9 j4 u, Y<p>为了保持简单,我们先定义以下两个类型:</p>6 [/ o3 S5 D: T4 ~/ z" |
<pre><code class="language-c#">// 定义新增Post的参数2 [3 ^1 ]% m" P+ J$ D
public record AddPostInput(string Title, string Author);0 o6 m: p& K- h p# n
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// 定义新增Post的返回对象& b( i' c2 _: B5 Q5 p! S
public record AddPostPayload(Post Post);
* s8 ~- q+ Z' C' h* |</code></pre>' P3 r5 n: H( V2 b8 b
<p>新建<code>Mutation.cs</code>用来定义相关接口:</p> F; O% u0 Z( k
<ul>8 X B( {5 Q/ E4 b1 R
<li><code>Mutation.cs</code></li>8 C, q2 y. Z9 J, N
</ul>: a1 ?' g8 ~+ x% N) {9 k! G. O; G! |
<pre><code class="language-c#">namespace PostGraphi.Api.GraphQL;4 U2 ~, G3 ^: m" ]+ m. W6 I
, C9 ?& ?5 u2 j4 \- g, ppublic class Mutation9 e3 n/ S: U1 J/ T" m+ @
{
" m' S+ n3 @8 V R; e; k. s public async Task<AddPostPayload> AddPostAsync(AddPostInput input, [Service] IRepository<Post> repository)% a. S1 \( j: `0 w) E' {' ^
{
* m" w% s I, f9 w2 Y return new AddPostPayload(await repository.AddAsync(new Post4 E7 L( n1 f% f! B/ m
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Title = input.Title,
$ M9 w! w' N7 @# i8 q& K8 K' l8 U6 r Author = input.Author( E+ B* b/ w8 x) u- q* v
}));
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</code></pre>
% R1 `8 {2 H# f& l' p<p>最后在注入服务的地方进行配置:</p>. d+ U8 \# o+ Y$ K8 \# A+ c. v
<ul>
. z: F, U& Z" _/ @! E. Y, p+ g; X( W<li><code>ProgramExtensions.cs</code></li>- Y; H) j5 @ z' H
</ul>
) W5 N% @4 {: K6 H<pre><code class="language-c#">builder.Services
6 H: _2 s* {0 f: r7 \ .AddGraphQLServer()! W+ f3 g7 C4 v8 u
.SetPagingOptions(new PagingOptions2 C4 O5 p1 ]7 G$ o, g
{
$ e' A+ v8 n( r9 o MaxPageSize = 50,: a3 K- N+ h/ @7 n5 G
IncludeTotalCount = true
! e% J% F# ~) H1 y& F. `8 J })
q* N( i% W; l. y: A .AddFiltering()
! r, `/ n" ^0 i .AddProjections()8 }2 Q' c. `9 r; K* s0 X+ X
.AddSorting() n' H' A% B* ^, k
.AddQueryType<Query>()1 j- F# }- h( S0 V9 Q
.AddMutationType<Mutation>()
2 ? H% }. ~* y- w .AddMutationConventions(new MutationConventionOptions" e& Z! p" K" i( \
{. q+ b# k+ _0 I
ApplyToAllMutations = true,$ c3 h3 d9 F: V3 A' [
InputArgumentName = "input",' U) L e. e# ]" b3 y M9 T: Q9 w
InputTypeNamePattern = "{MutationName}Input",
6 @3 h) ~; S/ V! ?+ A) A PayloadTypeNamePattern = "{MutationName}Payload",
+ Q: e4 v0 }- m" L$ O. s PayloadErrorTypeNamePattern = "{MutationName}Error",
3 T4 o9 }7 E1 d* g PayloadErrorsFieldName = "errors"+ i8 L0 M% j: c8 d
})
8 N" _4 D K) k9 h# w4 o, R .AddType<PostType>();
" V8 t2 K' k* ` l* ?3 v" [8 y</code></pre>7 [$ }- P3 \: l" W7 }& w: m
<p>这样就实现了新增Post的需求,下面我们来验证一下。</p>
! k7 c: A7 D& g0 `2 Z<h2 id="验证">验证</h2>3 |* @' [9 ?2 q2 ^
<p>启动<code>Api</code>项目,调用接口:</p>- X$ \9 W. Y9 I- v
<p><img src="https://img2022.cnblogs.com/blog/2487237/202202/2487237-20220211104544617-1400586374.png" ></p> X' w% p$ O; l
<p>终端的日志输出如下:</p>
/ M x6 @+ v0 h- P$ R<pre><code class="language-bash">[10:45:15 INF] Executed DbCommand (1ms) [Parameters=[@p0='?' (DbType = Guid), @p1='?', @p2='?' (Size = 13), @p3='?', @p4='?' (DbType = DateTime), @p5='?', @p6='?' (DbType = DateTime), @p7='?', @p8='?', @p9='?' (DbType = DateTime), @p10='?' (Size = 30)], CommandType='Text', CommandTimeout='30']# s* r! y% `* ?1 W! `6 e; F% d' B( p
INSERT INTO "Posts" ("Id", "Abstraction", "Author", "Content", "Created", "CreatedBy", "LastModified", "LastModifiedBy", "Link", "PublishedAt", "Title")
# t" R: N' m8 X- b7 b; SVALUES (@p0, @p1, @p2, @p3, @p4, @p5, @p6, @p7, @p8, @p9, @p10);) A& E+ c b2 M
[10:45:15 INF] Executed endpoint 'Hot Chocolate GraphQL Pipeline'4 ]% M; }7 B, P2 Y6 K1 v6 d
</code></pre>
}1 u% X" l9 o3 |6 D<p>可以看到新建的Post已经存储到数据库中了,我们可以通过查询接口来获取详情:</p>
/ R4 Z+ V' O; d/ ]3 c<p><img src="https://img2022.cnblogs.com/blog/2487237/202202/2487237-20220211104851825-1533915064.png" ></p>
+ X8 S$ d3 M1 R<h2 id="总结">总结</h2>
" \; E! N; R9 f* y<p>在本文中我们实现了简单的新增Post操作,这里还有一些涉及到错误处理的内容,我没有在文章中演示,可以参考官方文档 <a href="https://chillicream.com/docs/hotchocolate/defining-a-schema/mutations/#errors">Errors</a>,在自定义异常对象后,有三种方式可以进行错误处理:直接返回异常;使用异常工厂方法;使用构造函数。甚至可以在<code>AggregateExceptions</code>中一次性返回多个异常。基本思路都是通过添加属性<code>[Error(typeof(SomeUserDefinedException))]</code>来实现的。</p>
, x* l) f+ B0 P' j2 U3 M4 H/ O0 M( p<p>在下一篇文章中,我们通过<code>Mutation</code>对已有数据进行更新。</p>
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