`FST_ERR_REP_ALREADY_SENT` when using `res.send()`

I've setup context as such:

import { CreateFastifyContextOptions } from '@trpc/server/adapters/fastify';
import models from '../database/models.js';

interface CreateInnerContextOptions extends Partial<CreateFastifyContextOptions> {
    models: typeof models;
}

export async function createInnerContext(opts: CreateInnerContextOptions) {
    return {
        models: opts.models
    };
}

export async function createContext(fastifyOptions: CreateFastifyContextOptions) {
    const innerContext = await createInnerContext({ models });

    return { ...fastifyOptions, ...innerContext };
}

export type Context = Awaited<typeof createContext>;

import { CreateFastifyContextOptions } from '@trpc/server/adapters/fastify';
import models from '../database/models.js';

interface CreateInnerContextOptions extends Partial<CreateFastifyContextOptions> {
    models: typeof models;
}

export async function createInnerContext(opts: CreateInnerContextOptions) {
    return {
        models: opts.models
    };
}

export async function createContext(fastifyOptions: CreateFastifyContextOptions) {
    const innerContext = await createInnerContext({ models });

    return { ...fastifyOptions, ...innerContext };
}

export type Context = Awaited<typeof createContext>;

And a procedure like this:

import generateCampaignReport from '../../../../xlsx_reports/generateCampaignReport.js';
import { publicProcedure } from '../../../init.js';
import objectIdSchema from '../../../zod_schemas/ObjectId.js';
import { z } from 'zod';
import { Types } from 'mongoose';

export default publicProcedure
    .input(
        z.object({
            campaignId: objectIdSchema
        })
    )
    .mutation(async ({ input, ctx }) => {
        const { campaignId } = input;
        const { res } = ctx;

        res.header('Content-Type', 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');
        res.header('Content-Disposition', `attachment; filename="clipx_workbook.xlsx"`);

        const buffer = await generateCampaignReport(new Types.ObjectId(campaignId));
        res.send(buffer);
    });

import generateCampaignReport from '../../../../xlsx_reports/generateCampaignReport.js';
import { publicProcedure } from '../../../init.js';
import objectIdSchema from '../../../zod_schemas/ObjectId.js';
import { z } from 'zod';
import { Types } from 'mongoose';

export default publicProcedure
    .input(
        z.object({
            campaignId: objectIdSchema
        })
    )
    .mutation(async ({ input, ctx }) => {
        const { campaignId } = input;
        const { res } = ctx;

        res.header('Content-Type', 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');
        res.header('Content-Disposition', `attachment; filename="clipx_workbook.xlsx"`);

        const buffer = await generateCampaignReport(new Types.ObjectId(campaignId));
        res.send(buffer);
    });

Solution:

this looks like it should be an api endpoint outside of trpc

Jump to solution

4 Replies

TeixeiraOP•2w ago

which is returning the following error:

[11:02:09.965] WARN (8548): Reply was already sent, did you forget to "return reply" in "/campaigns.generateReport?batch=1" (POST)?
    reqId: "req-3"
    err: {
      "type": "FastifyError",
      "message": "Reply was already sent, did you forget to \"return reply\" in \"/campaigns.generateReport?batch=1\" (POST)?",
      "stack":
          FastifyError: Reply was already sent, did you forget to "return reply" in "/campaigns.generateReport?batch=1" (POST)?
              at Reply.send (C:\Users\jpedr\Documents\Workshop\Work\clipx\node_modules\fastify\lib\reply.js:132:26)
              at fastifyRequestHandler (file://.../node_modules/@trpc/server/dist/adapters/fastify/fastifyRequestHandler.mjs:43:20)
              at Object.<anonymous> (file://.../node_modules/@trpc/server/dist/adapters/fastify/fastifyTRPCPlugin.mjs:29:9)
      "code": "FST_ERR_REP_ALREADY_SENT",
      "name": "FastifyError",
      "statusCode": 500
    }

[11:02:09.965] WARN (8548): Reply was already sent, did you forget to "return reply" in "/campaigns.generateReport?batch=1" (POST)?
    reqId: "req-3"
    err: {
      "type": "FastifyError",
      "message": "Reply was already sent, did you forget to \"return reply\" in \"/campaigns.generateReport?batch=1\" (POST)?",
      "stack":
          FastifyError: Reply was already sent, did you forget to "return reply" in "/campaigns.generateReport?batch=1" (POST)?
              at Reply.send (C:\Users\jpedr\Documents\Workshop\Work\clipx\node_modules\fastify\lib\reply.js:132:26)
              at fastifyRequestHandler (file://.../node_modules/@trpc/server/dist/adapters/fastify/fastifyRequestHandler.mjs:43:20)
              at Object.<anonymous> (file://.../node_modules/@trpc/server/dist/adapters/fastify/fastifyTRPCPlugin.mjs:29:9)
      "code": "FST_ERR_REP_ALREADY_SENT",
      "name": "FastifyError",
      "statusCode": 500
    }

as far as I am aware I can't return the Buffer directly as it would be resolved to JSON so I have to use res.send. Is there a way I can make the function not attempt to send another reply when it's returning? Using @trpc/server@11.0.0-rc.730+776d07336, fastify@5.2.1, node v22.11.0

Alex / KATT 🐱•2w ago

- trpc responses are limited to json at the moment - if you're using the batch stream link, headers are sent before reaching the mutation you shouldn't access res.send() inside of a procedure

Solution

Alex / KATT 🐱•2w ago

this looks like it should be an api endpoint outside of trpc

TeixeiraOP•2w ago

Oh, that's a bummer 😦 Alright thank you very much

`FST_ERR_REP_ALREADY_SENT` when using `res.send()`

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