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TanStack is a community of passionate software engineers striving for high-quality, open-source software for web devs

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react-query-questions

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stormy-gold

8/20/2025

Unit testing with Tanstack Start

Hey guys, I can't find any info on this so hoping someone here can help. I want to put unit tests in place for some of my server functions and middleware but I haven't been able to figure out how to call the relevant handlers. Currently the only way I can tests the handler logic is to split it out from the server function definition (i.e. export a function and supply to the .handler / .server methods) but this feels like overkill and I'm not sure I want to expose functions just for the sake of testing discrete parts of the flow - doesn't feel right....

other-emerald

8/20/2025

dynamic middleware generation???

I did reach out to Tanner on twitter regarding this as well here but does anyone know if we can generate middleware dynamicaly on the fly? or must it be generated statically so bundled at build time. this as an example would be a dynamic middleware generator that checks user has the correct permissions in screenshot. if can't be done I'll just do as a utility function at top of handler but this would be nice if can do....

extended-yellow

8/19/2025

How to be assured environment variables secrets sensitive data are not being leaked?

Coming from nextjs, the server-only package seems to be separate from nextjs, but using it with tanstack start does not seem like I'm using it correctly. Basically setting in any file that references an environment variable or business logic. I removed all implementations and did a test with a single secret file being imported into a createServerFileRoute file, and the whole client app crashes complaining about not using it in client code, but it is not being used in client code. I go...

harsh-harlequin

8/19/2025

Hydration error when streaming data from data loader

Hello, I am facing an hydration error when I try to use an unresolved promise in the route loader. It happens on page load, not on hmr. I was doing some basic tests so the code is very close to the boilerplate : ...

unwilling-turquoise

8/19/2025

TRPC with ensureQueryData/Prefetch

Hey Folks, I'm having some issues with using trpc and fetching on the server before sending it down with trpc / tanstack query am I doing something wrong here?...

modern-teal

8/17/2025

`createServerFn` Zod validation works, but TS doesn’t catch invalid params at callsite?

I'm using createServerFn from @tanstack/react-start with Zod validation to define sendEmailFn. Everything works at runtime (thanks to .validator(...)), but TypeScript doesn't enforce the parameter shape when calling sendEmailFn()—I can omit fields or add invalid ones, and TS doesn’t complain. Only Zod throws at runtime. Why isn't TypeScript checking the input types at compile-time? Example code ``` import { createServerFn } from '@tanstack/react-start';...

zesty-coffee

8/17/2025

vite-pwa plugin does not work in production builds

dev-sw.js works, but the core issue is that sw.js doesn't get built in prod output. is that possible that rollup might be causing the issue? if so, how to ignore that during the build. here's my repo with a workaround:...

equal-aqua

8/17/2025

How do i read auth tokens during http request with axios?

I want to call react query inside loader but my axios don't have auth tokens in header (currently doing session cookie) but my auth is being failed due to lack of auth tokens. how do i handle auth tokens in ssr pages?...

national-gold

8/17/2025

A server function that is not available in production

I'm adding a server function that will only be used in development, I was wondering if there's a way to mark it as such and remove it from the final bundle. I'm currently calling it from a custom plugin in tanstack devtools. I've tried to put a condition like import.meta.DEV && customPlugin to force it to only be added in dev, but after buliding the app I can still seed the server function in the bundle....

sensitive-blue

8/16/2025

prevent db module going to client

I'm trying to execute a db query on my route loader, but my db file imports "server-only" and I'm getting this error

This module cannot be imported from a Client Component module. It should only be used from a Server Component.

This module cannot be imported from a Client Component module. It should only be used from a Server Component.

...

absent-sapphire

8/15/2025

How do I disable <StrictMode /> during development?

I'm console.log() in beforeLoad and loader in various places and sometimes its running twice. I suspect it's because of <StrictMode /> during development causing it to render twice. I would like to turn it off so I can follow these console.log() clearly

flat-fuchsia

8/14/2025

Resend email not working with TanStack Start

I want to use Resend and react email to send email verification when I sign up using better auth, but I can't make it work in tanstack start. Neither Server Functions nor Server Routes were able to send email.

compatible-crimson

8/14/2025

using createIsomorphicFn how can i get router context?

Hello! I'm trying to get the route context using a createIsomorphicFn. Client I injected a window variable and it works fine. But on the server I have not idea how to get it. I can see tanstack core uses a getStartContext(), but it is not exposed, so I have no way of accessing that exported const in there. Is there a way of accessing to the context?? And for the client, is there a better way instead of having to use window? The use case is because the fetch binding of cloudflare I need to distinct the fetch fn, in the client using normal fetch and in the server using cloudflare fetch. Then i inject the auth, locale and currency to headers. And this is why i want to access to the context as that info lives there....

afraid-scarlet

8/14/2025

Non-serializable data across server/client boundary

I'm trying to fetch some prisma data in my createServerFn, but i get an error when that data includes non JSON-serializable objects like prisma's JsonValue (as demonstrated below). What is the recommended way of dealing with this issue? 1. Creating DTO for each model and transform non serializable data on the server into something serializable 2. I've seen people recommend return JSON.parse(JSON.stringify(response)) but then i lose type safety...

metropolitan-bronze

8/13/2025

Cold start with netlify

Hey all! I’m using the Netlify hosting option for Tanstack Start, and I’m finding that the cold starts are super slow. It usually takes a few seconds for a first load. Does anyone know of any solutions to deal with this? Does my website just need to get more popular? Is it against the Netlify TOS to hit my website automatically on a cron schedule? Let me know if this question is better meant for Netlify support, but I figured I’d ask here in case other Tanstack Start users have run into this. Thanks!...

sunny-green

8/13/2025

How to properly redirect client-side

Hi, should i use throw redirect or useNavigate() client-side? It seems like both works. Example: User signs a form, onSuccess redirect the user to another page....

flat-fuchsia

8/13/2025

Resend with TanStack Start

How can I use resend with tanstack start? In their docs, they have next js integration Send email using React Create an API file under pages/api/send.ts if you’re using the Pages Router or create a route file under app/api/send/route.ts if you’re using the App Router....

rare-sapphire

8/12/2025

UI Elements stop working w/ beforeLoad

I'm encountering a strange bug where if I call getCookie in my route, the UI elements (in this case tabs) don't work. Here is the code: ```...

foreign-sapphire

8/12/2025

How to kill an SSE stream when the page is exited gracefully

Currently I'm trying to use the Request.signal from getWebRequest but I don't think it works, is this something I should be using the router for?

equal-aqua

8/12/2025

"Multiple instances of Solid" even when using React

https://github.com/TanStack/router/issues/4936

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TanStack

TanStack is a community of passionate software engineers striving for high-quality, open-source software for web devs

TanStack

TanStack is a community of passionate software engineers striving for high-quality, open-source software for web devs