类型推断

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在客户端访问 API 的类型信息通常很有价值。为此，您可以直接从 AppRouter 中推断出包含的类型。

@trpc/server 提供以下辅助类型，帮助从你的 @trpc/server 路由器导出的 AppRouter 中推断这些类型：

• inferRouterInputs<TRouter>

• inferRouterOutputs<TRouter>

• inferProcedureInput<TProcedure>

• inferProcedureOutput<TProcedure>

• inferSubscriptionInput<TProcedure>

• inferSubscriptionOutput<TProcedure>

输入输出类型推断

假设我们有以下示例路由：

server.ts
ts
import { initTRPC } from '@trpc/server';
import { z } from "zod";
 
const t = initTRPC.create();
 
const appRouter = t.router({
  post: t.router({
    list: t.procedure
      .query(() => {
        // imaginary db call
        return [{ id: 1, title: 'tRPC is the best!' }];
    }),
    byId: t.procedure
      .input(z.string())
      .query((opts) => {
        // imaginary db call
        return { id: 1, title: 'tRPC is the best!' };
    }),
    create: t.procedure
      .input(z.object({ title: z.string(), text: z.string(), }))
      .mutation((opts) => {
        // imaginary db call
        return { id: 1, ...opts.input };
    }),
    onPostAdd: t.procedure
      .input(z.object({ authorId: z.string() }))
      .subscription(async function* ({ input }) {
        // imaginary event source
        yield {
          id: 1,
          title: 'tRPC is the best!',
          authorId: input.authorId,
        };
    }),
  }),
});
 
export type AppRouter = typeof appRouter;

server.ts
ts
import { initTRPC } from '@trpc/server';
import { z } from "zod";
 
const t = initTRPC.create();
 
const appRouter = t.router({
  post: t.router({
    list: t.procedure
      .query(() => {
        // imaginary db call
        return [{ id: 1, title: 'tRPC is the best!' }];
    }),
    byId: t.procedure
      .input(z.string())
      .query((opts) => {
        // imaginary db call
        return { id: 1, title: 'tRPC is the best!' };
    }),
    create: t.procedure
      .input(z.object({ title: z.string(), text: z.string(), }))
      .mutation((opts) => {
        // imaginary db call
        return { id: 1, ...opts.input };
    }),
    onPostAdd: t.procedure
      .input(z.object({ authorId: z.string() }))
      .subscription(async function* ({ input }) {
        // imaginary event source
        yield {
          id: 1,
          title: 'tRPC is the best!',
          authorId: input.authorId,
        };
    }),
  }),
});
 
export type AppRouter = typeof appRouter;

使用这些辅助类型，我们可以推断路由的类型。以下示例展示了如何推断 post.create 过程的类型：

client.ts
ts
import type { inferRouterInputs, inferRouterOutputs } from '@trpc/server';
import type { AppRouter } from './server';
 
type RouterInput = inferRouterInputs<AppRouter>;
type RouterOutput = inferRouterOutputs<AppRouter>;
 
type PostCreateInput = RouterInput['post']['create'];
type PostCreateOutput = RouterOutput['post']['create'];

client.ts
ts
import type { inferRouterInputs, inferRouterOutputs } from '@trpc/server';
import type { AppRouter } from './server';
 
type RouterInput = inferRouterInputs<AppRouter>;
type RouterOutput = inferRouterOutputs<AppRouter>;
 
type PostCreateInput = RouterInput['post']['create'];
type PostCreateOutput = RouterOutput['post']['create'];

推断单个过程类型

如果你已经能够访问路由中的特定过程，可以直接推断其输入或输出类型：

client.ts
ts
import type {
  inferProcedureInput,
  inferProcedureOutput,
} from '@trpc/server';
import type { AppRouter } from './server';
 
type PostByIdInput = inferProcedureInput<AppRouter['post']['byId']>;
type PostByIdOutput = inferProcedureOutput<AppRouter['post']['byId']>;

client.ts
ts
import type {
  inferProcedureInput,
  inferProcedureOutput,
} from '@trpc/server';
import type { AppRouter } from './server';
 
type PostByIdInput = inferProcedureInput<AppRouter['post']['byId']>;
type PostByIdOutput = inferProcedureOutput<AppRouter['post']['byId']>;

对于订阅，你可以推断订阅输入及发出的数据类型：

client.ts
ts
import type {
  inferSubscriptionInput,
  inferSubscriptionOutput,
} from '@trpc/server';
import type { AppRouter } from './server';
 
type OnPostAddInput = inferSubscriptionInput<AppRouter['post']['onPostAdd']>;
type OnPostAddOutput = inferSubscriptionOutput<AppRouter['post']['onPostAdd']>;

client.ts
ts
import type {
  inferSubscriptionInput,
  inferSubscriptionOutput,
} from '@trpc/server';
import type { AppRouter } from './server';
 
type OnPostAddInput = inferSubscriptionInput<AppRouter['post']['onPostAdd']>;
type OnPostAddOutput = inferSubscriptionOutput<AppRouter['post']['onPostAdd']>;

推断 TRPCClientError 类型

推断 AppRouter 的错误类型同样非常实用

client.ts
ts
import { TRPCClientError } from '@trpc/client';
import type { AppRouter } from './server';
import { trpc } from './trpc';
 
export function isTRPCClientError(
  cause: unknown,
): cause is TRPCClientError<AppRouter> {
  return cause instanceof TRPCClientError;
}
 
async function main() {
  try {
    await trpc.post.byId.query('1');
  } catch (cause) {
    if (isTRPCClientError(cause)) {
      // `cause` is now typed as your router's `TRPCClientError`
      console.log('data', cause.data);
    } else {
      // [...]
    }
  }
}
 
main();

client.ts
ts
import { TRPCClientError } from '@trpc/client';
import type { AppRouter } from './server';
import { trpc } from './trpc';
 
export function isTRPCClientError(
  cause: unknown,
): cause is TRPCClientError<AppRouter> {
  return cause instanceof TRPCClientError;
}
 
async function main() {
  try {
    await trpc.post.byId.query('1');
  } catch (cause) {
    if (isTRPCClientError(cause)) {
      // `cause` is now typed as your router's `TRPCClientError`
      console.log('data', cause.data);
    } else {
      // [...]
    }
  }
}
 
main();