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signIn function not returning JSON to server

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Silver Fox posted this in #help-forum
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Silver FoxOP
export async function POST(
  request: Request
) {
  const body = await request.json()
  console.log(JSON.stringify(body));

  const validatedFields = LoginSchema.safeParse(body)

  if (!validatedFields.success) {
    return Response.json({ error: "Invalid credentials!" }, { status: 500 })
  }
  console.log("test");

  const { email, password } = validatedFields.data
  try {
    await signIn("credentials", {
      email,
      password,
      redirectTo: DEFAULT_LOGIN_REDIRECT
    })
    // return Response.json({ success: true, message: "Login successful!" });
  } catch (error) {


    if (error instanceof AuthError) {
      switch (error.type) {
        case "CredentialsSignin":
          return Response.json({ error: "Invalid credentials!" }, { status: 500 })
        default:
          return Response.json({ error: "Something went wrong!" }, { status: 500 })
      }
    }
    throw error
  }

}

this is the app/api/login
and this is how i am calling it
function onSubmit(values: z.infer<typeof LoginSchema>) {
    startTransition(async () => {
      const response = await fetch("/api/login", {
        method: "POST",
        headers: {
          "Content-Type": "application/json",
        },
        body: JSON.stringify(values),
      });
      console.log(response)
      const data = await response.json()
      if (response.ok && data.success) {
        setStatus("success")
        setStatusMessage(data.success)
      } else {
        setStatus("error")
        setStatusMessage(data.error)
      }
    });
  }

i get this error
syntaxerror: Unexpected token '<', "<!DOCTYPE "... is not valid JSON

10 Replies

Silver FoxOP
am i using the signIn function correctly?
Toyger
you need check what response you get from /api/login in devtools network tab either with postman/insomnia/etc...
because it's definetely not json in response
after it redirects the app continues to work fine unless i try to login in again or the session expires
Toyger
didn't notice signin at first, signIn is client component feature, you can't use it in api. you neen to login user through client not through your api.
@Toyger didn't notice signin at first, `signIn` is client component feature, you can't use it in api. you neen to login user through client not through your api.
Silver FoxOP
makes sense but how does it work with server actions then 🤔 
export const login = async (
.....
.....
  try {
      await signIn("credentials", {
        email,
        password,
        redirectTo: callbackUrl || DEFAULT_LOGIN_REDIRECT,
      })
    } catch (error) {
      if (error instanceof AuthError) {
        switch (error.type) {
          case "CredentialsSignin":
            return { error: "Invalid credentials!" }
          default:
            return { error: "Something went wrong!" }
        }
      }
  
      throw error;
  }
};

this works if I use server actions
and then on the client side 
    startTransition(() => {
      login(values, callbackUrl)
        .then((data) => {
          if (data?.error) {
            form.reset();
            setError(data.error);
          }
        })
        .catch(() => setError("Something went wrong"));

  };
@Toyger not sure why it working, but if it working then why you are not using server actions?
Silver FoxOP
just figured that out now, i will be using server actions for the login, still wierd
anyways thanks for the help :blob_wave: