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服务端调用

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当需要在托管服务的同一服务器中直接调用过程（procedure）时，可使用 createCallerFactory() 实现。这在服务端调用和 tRPC 过程的集成测试中非常有用。

信息

不应在 procedure 内部使用 createCaller 调用其他 procedure。这会（可能）重复创建 context、重新执行所有 middleware 以及验证输入，造成不必要的开销——这些操作在当前 procedure 中已完成。正确的做法是将共享逻辑提取为独立函数，然后在 procedure 中调用该函数，如下图所示：

创建调用器​

通过 t.createCallerFactory 函数可为任意路由创建服务端调用器。首先向 createCallerFactory 传入目标路由参数，该函数将返回一个新函数，您可向其传递后续过程调用所需的 Context。

基础示例​

我们创建包含文章列表查询和新增文章变更操作的路由，然后分别调用各方法。

ts
import { initTRPC } from '@trpc/server';
import { z } from 'zod';
 
type Context = {
  foo: string;
};
 
const t = initTRPC.context<Context>().create();
 
const publicProcedure = t.procedure;
const { createCallerFactory, router } = t;
 
interface Post {
  id: string;
  title: string;
}
const posts: Post[] = [
  {
    id: '1',
    title: 'Hello world',
  },
];
const appRouter = router({
  post: router({
    add: publicProcedure
      .input(
        z.object({
          title: z.string().min(2),
        }),
      )
      .mutation((opts) => {
        const post: Post = {
          ...opts.input,
          id: `${Math.random()}`,
        };
        posts.push(post);
        return post;
      }),
    list: publicProcedure.query(() => posts),
  }),
});
 
// 1. create a caller-function for your router
const createCaller = createCallerFactory(appRouter);
 
// 2. create a caller using your `Context`
const caller = createCaller({
  foo: 'bar',
});
 
// 3. use the caller to add and list posts
const addedPost = await caller.post.add({
  title: 'How to make server-side call in tRPC',
});
 
const postList = await caller.post.list();
         
const postList: Post[]
ts
import { initTRPC } from '@trpc/server';
import { z } from 'zod';
 
type Context = {
  foo: string;
};
 
const t = initTRPC.context<Context>().create();
 
const publicProcedure = t.procedure;
const { createCallerFactory, router } = t;
 
interface Post {
  id: string;
  title: string;
}
const posts: Post[] = [
  {
    id: '1',
    title: 'Hello world',
  },
];
const appRouter = router({
  post: router({
    add: publicProcedure
      .input(
        z.object({
          title: z.string().min(2),
        }),
      )
      .mutation((opts) => {
        const post: Post = {
          ...opts.input,
          id: `${Math.random()}`,
        };
        posts.push(post);
        return post;
      }),
    list: publicProcedure.query(() => posts),
  }),
});
 
// 1. create a caller-function for your router
const createCaller = createCallerFactory(appRouter);
 
// 2. create a caller using your `Context`
const caller = createCaller({
  foo: 'bar',
});
 
// 3. use the caller to add and list posts
const addedPost = await caller.post.add({
  title: 'How to make server-side call in tRPC',
});
 
const postList = await caller.post.list();
         
const postList: Post[]

集成测试使用示例​

示例取自 https://github.com/trpc/examples-next-prisma-starter/blob/main/src/server/routers/post.test.ts

ts
import { inferProcedureInput } from '@trpc/server';
import { createContextInner } from '../context';
import { AppRouter, createCaller } from './_app';
test('add and get post', async () => {
  const ctx = await createContextInner({});
  const caller = createCaller(ctx);
  const input: inferProcedureInput<AppRouter['post']['add']> = {
    text: 'hello test',
    title: 'hello test',
  };
  const post = await caller.post.add(input);
  const byId = await caller.post.byId({ id: post.id });
  expect(byId).toMatchObject(input);
});
ts
import { inferProcedureInput } from '@trpc/server';
import { createContextInner } from '../context';
import { AppRouter, createCaller } from './_app';
test('add and get post', async () => {
  const ctx = await createContextInner({});
  const caller = createCaller(ctx);
  const input: inferProcedureInput<AppRouter['post']['add']> = {
    text: 'hello test',
    title: 'hello test',
  };
  const post = await caller.post.add(input);
  const byId = await caller.post.byId({ id: post.id });
  expect(byId).toMatchObject(input);
});

router.createCaller()​

通过 router.createCaller({}) 函数（首个参数为 Context）可获取 RouterCaller 实例。

输入查询示例​

我们创建包含输入查询的路由，然后异步调用 greeting 过程获取结果。

ts
import { initTRPC } from '@trpc/server';
import { z } from 'zod';
 
const t = initTRPC.create();
 
const router = t.router({
  // Create procedure at path 'greeting'
  greeting: t.procedure
    .input(z.object({ name: z.string() }))
    .query((opts) => `Hello ${opts.input.name}`),
});
 
const caller = router.createCaller({});
const result = await caller.greeting({ name: 'tRPC' });
        
const result: string
ts
import { initTRPC } from '@trpc/server';
import { z } from 'zod';
 
const t = initTRPC.create();
 
const router = t.router({
  // Create procedure at path 'greeting'
  greeting: t.procedure
    .input(z.object({ name: z.string() }))
    .query((opts) => `Hello ${opts.input.name}`),
});
 
const caller = router.createCaller({});
const result = await caller.greeting({ name: 'tRPC' });
        
const result: string

变更操作示例​

我们创建包含变更操作的路由，然后异步调用 post 过程获取结果。

ts
import { initTRPC } from '@trpc/server';
import { z } from 'zod';
 
const posts = ['One', 'Two', 'Three'];
 
const t = initTRPC.create();
const router = t.router({
  post: t.router({
    add: t.procedure.input(z.string()).mutation((opts) => {
      posts.push(opts.input);
      return posts;
    }),
  }),
});
 
const caller = router.createCaller({});
const result = await caller.post.add('Four');
        
const result: string[]
ts
import { initTRPC } from '@trpc/server';
import { z } from 'zod';
 
const posts = ['One', 'Two', 'Three'];
 
const t = initTRPC.create();
const router = t.router({
  post: t.router({
    add: t.procedure.input(z.string()).mutation((opts) => {
      posts.push(opts.input);
      return posts;
    }),
  }),
});
 
const caller = router.createCaller({});
const result = await caller.post.add('Four');
        
const result: string[]

带中间件的上下文示例​

我们在执行 secret 过程前创建中间件来校验上下文。下方两个示例中：前者因上下文不符合中间件逻辑而失败，后者则正确执行。


信息

中间件会在所有过程调用前执行。


ts
import { initTRPC, TRPCError } from '@trpc/server';
 
type Context = {
  user?: {
    id: string;
  };
};
const t = initTRPC.context<Context>().create();
 
const protectedProcedure = t.procedure.use((opts) => {
  const { ctx } = opts;
  if (!ctx.user) {
    throw new TRPCError({
      code: 'UNAUTHORIZED',
      message: 'You are not authorized',
    });
  }
 
  return opts.next({
    ctx: {
      // Infers that the `user` is non-nullable
      user: ctx.user,
    },
  });
});
 
const router = t.router({
  secret: protectedProcedure.query((opts) => opts.ctx.user),
});
 
{
  // ❌ this will return an error because there isn't the right context param
  const caller = router.createCaller({});
 
  const result = await caller.secret();
}
 
{
  // ✅ this will work because user property is present inside context param
  const authorizedCaller = router.createCaller({
    user: {
      id: 'KATT',
    },
  });
  const result = await authorizedCaller.secret();
          
const result: {
    id: string;
}
}
ts
import { initTRPC, TRPCError } from '@trpc/server';
 
type Context = {
  user?: {
    id: string;
  };
};
const t = initTRPC.context<Context>().create();
 
const protectedProcedure = t.procedure.use((opts) => {
  const { ctx } = opts;
  if (!ctx.user) {
    throw new TRPCError({
      code: 'UNAUTHORIZED',
      message: 'You are not authorized',
    });
  }
 
  return opts.next({
    ctx: {
      // Infers that the `user` is non-nullable
      user: ctx.user,
    },
  });
});
 
const router = t.router({
  secret: protectedProcedure.query((opts) => opts.ctx.user),
});
 
{
  // ❌ this will return an error because there isn't the right context param
  const caller = router.createCaller({});
 
  const result = await caller.secret();
}
 
{
  // ✅ this will work because user property is present inside context param
  const authorizedCaller = router.createCaller({
    user: {
      id: 'KATT',
    },
  });
  const result = await authorizedCaller.secret();
          
const result: {
    id: string;
}
}

Next.js API 端点示例​

技巧

此示例展示如何在 Next.js API 端点中使用调用器。注意 tRPC 已自动创建 API 端点，本示例仅演示如何从自定义端点调用过程。

ts
import { TRPCError } from '@trpc/server';
import { getHTTPStatusCodeFromError } from '@trpc/server/http';
import { appRouter } from '~/server/routers/_app';
import type { NextApiRequest, NextApiResponse } from 'next';
 
type ResponseData = {
  data?: {
    postTitle: string;
  };
  error?: {
    message: string;
  };
};
 
export default async (
  req: NextApiRequest,
  res: NextApiResponse<ResponseData>,
) => {
  /** We want to simulate an error, so we pick a post ID that does not exist in the database. */
  const postId = `this-id-does-not-exist-${Math.random()}`;
 
  const caller = appRouter.createCaller({});
 
  try {
    // the server-side call
    const postResult = await caller.post.byId({ id: postId });
 
    res.status(200).json({ data: { postTitle: postResult.title } });
  } catch (cause) {
    // If this a tRPC error, we can extract additional information.
    if (cause instanceof TRPCError) {
      // We can get the specific HTTP status code coming from tRPC (e.g. 404 for `NOT_FOUND`).
      const httpStatusCode = getHTTPStatusCodeFromError(cause);
 
      res.status(httpStatusCode).json({ error: { message: cause.message } });
      return;
    }
 
    // This is not a tRPC error, so we don't have specific information.
    res.status(500).json({
      error: { message: `Error while accessing post with ID ${postId}` },
    });
  }
};
ts
import { TRPCError } from '@trpc/server';
import { getHTTPStatusCodeFromError } from '@trpc/server/http';
import { appRouter } from '~/server/routers/_app';
import type { NextApiRequest, NextApiResponse } from 'next';
 
type ResponseData = {
  data?: {
    postTitle: string;
  };
  error?: {
    message: string;
  };
};
 
export default async (
  req: NextApiRequest,
  res: NextApiResponse<ResponseData>,
) => {
  /** We want to simulate an error, so we pick a post ID that does not exist in the database. */
  const postId = `this-id-does-not-exist-${Math.random()}`;
 
  const caller = appRouter.createCaller({});
 
  try {
    // the server-side call
    const postResult = await caller.post.byId({ id: postId });
 
    res.status(200).json({ data: { postTitle: postResult.title } });
  } catch (cause) {
    // If this a tRPC error, we can extract additional information.
    if (cause instanceof TRPCError) {
      // We can get the specific HTTP status code coming from tRPC (e.g. 404 for `NOT_FOUND`).
      const httpStatusCode = getHTTPStatusCodeFromError(cause);
 
      res.status(httpStatusCode).json({ error: { message: cause.message } });
      return;
    }
 
    // This is not a tRPC error, so we don't have specific information.
    res.status(500).json({
      error: { message: `Error while accessing post with ID ${postId}` },
    });
  }
};

错误处理​

createFactoryCaller 和 createCaller 函数可通过 onError 选项接收错误处理程序。该机制适用于抛出非 TRPCError 封装的错误，或以其他方式响应错误。传递给 createCallerFactory 的处理程序将先于 createCaller 的处理程序执行。 处理程序的调用参数与错误格式化器一致（不包含 shape 字段）：

ts
{
  ctx: unknown; // The request context
  error: TRPCError; // The TRPCError that was thrown
  path: string | undefined; // The path of the procedure that threw the error
  input: unknown; // The input that was passed to the procedure
  type: 'query' | 'mutation' | 'subscription' | 'unknown'; // The type of the procedure that threw the error
}
ts
{
  ctx: unknown; // The request context
  error: TRPCError; // The TRPCError that was thrown
  path: string | undefined; // The path of the procedure that threw the error
  input: unknown; // The input that was passed to the procedure
  type: 'query' | 'mutation' | 'subscription' | 'unknown'; // The type of the procedure that threw the error
}
ts
import { initTRPC } from '@trpc/server';
import { z } from 'zod';
 
const t = initTRPC
  .context<{
    foo?: 'bar';
  }>()
  .create();
 
const router = t.router({
  greeting: t.procedure.input(z.object({ name: z.string() })).query((opts) => {
    if (opts.input.name === 'invalid') {
      throw new Error('Invalid name');
    }
 
    return `Hello ${opts.input.name}`;
  }),
});
 
const caller = router.createCaller(
  {
    /* context */
  },
  {
    onError: (opts) => {
      console.error('An error occurred:', opts.error);
    },
  },
);
 
// The following will log "An error occurred: Error: Invalid name", and then throw a plain error
//  with the message "This is a custom error"
await caller.greeting({ name: 'invalid' });
ts
import { initTRPC } from '@trpc/server';
import { z } from 'zod';
 
const t = initTRPC
  .context<{
    foo?: 'bar';
  }>()
  .create();
 
const router = t.router({
  greeting: t.procedure.input(z.object({ name: z.string() })).query((opts) => {
    if (opts.input.name === 'invalid') {
      throw new Error('Invalid name');
    }
 
    return `Hello ${opts.input.name}`;
  }),
});
 
const caller = router.createCaller(
  {
    /* context */
  },
  {
    onError: (opts) => {
      console.error('An error occurred:', opts.error);
    },
  },
);
 
// The following will log "An error occurred: Error: Invalid name", and then throw a plain error
//  with the message "This is a custom error"
await caller.greeting({ name: 'invalid' });