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Error Formatting

The error formatting in your router will be inferred all the way to your client (& React components)

Usage example highlighted

Adding custom formatting

server.ts

const router = trpc.router<Context>()
.formatError(({ shape, error }) => {
return {
...shape,
data: {
...shape.data,
zodError:
error.code === 'BAD_USER_INPUT' &&
error.cause instanceof ZodError
? error.cause.flatten()
: null,
};
};
})

Usage in React

components/MyComponent.tsx
export function MyComponent() {
const mutation = trpc.useMutation('addPost');

useEffect(() => {
mutation.mutate({ title: 'example' });
}, []);

if (mutation.error?.data?.zodError) {
// zodError will be inferred
return (
<pre>Error: {JSON.stringify(mutation.error.data.zodError, null, 2)}</pre>
);
}
return <>[...]</>;
}

All properties sent to formatError()

Since v8.x tRPC is compliant with JSON-RPC 2.0

{
error: TRPCError;
type: ProcedureType | 'unknown';
path: string | undefined;
input: unknown;
ctx: undefined | TContext;
shape: DefaultErrorShape; // the default error shape
}

DefaultErrorShape:


interface DefaultErrorData {
code: TRPC_ERROR_CODE_KEY;
httpStatus: number;
path?: string;
stack?: string;
}

interface DefaultErrorShape
extends TRPCErrorShape<TRPC_ERROR_CODE_NUMBER, DefaultErrorData> {
message: string;
code: TRPC_ERROR_CODE_NUMBER;
}