Custom error response using `GENERAL_ERROR` status

Sometimes, you may want to send a custom error message from your API override to display to the user on the frontend. This can be done by sending the following JSON response from the API:

{
    "status": "GENERAL_ERROR",
    "message": "Some custom error message"
}

If you are using our pre-built ReactJS UI, the above response will render the mesage "Some custom error message" on the frontend UI. For custom UI, you can read this response and display the message in an error UI. This response can be returned from most of the APIs exposed by the backend SDK.

Let's take an example in which we want to prevent the user from signing up (via email / password) unless their email is preapproved by the app's admin. For this, we will override the sign up API to check if the input email is approved or not, and if not, we prevent the sign up, and send a custom error message.

NodeJS
GoLang
Python
Other Frameworks

import EmailPassword from "supertokens-node/recipe/emailpassword";

EmailPassword.init({
    override: {
        apis: (oI) => {
            return {
                ...oI,
                signUpPOST: async function (input) {
                    let email = input.formFields.find(i => i.id === "email")!.value as string;

                    if (emailNotAllowed(email)) {
                        return {
                            status: "GENERAL_ERROR",
                            message: "You are not allowed to sign up. Please contact the app's admin to get permission"
                        }
                    }
                    return oI.signUpPOST!(input);
                }
            }
        }
    }
})

function emailNotAllowed(email: string) {
    // TODO: your impl to check if email is allowed or not
    return true;
}

import (
    "errors"

    "github.com/supertokens/supertokens-golang/recipe/emailpassword/epmodels"
    "github.com/supertokens/supertokens-golang/recipe/emailpassword"
    "github.com/supertokens/supertokens-golang/supertokens"
)

func main() {
    emailpassword.Init(&epmodels.TypeInput{
        Override: &epmodels.OverrideStruct{
            APIs: func(originalImplementation epmodels.APIInterface) epmodels.APIInterface {
                originalSignUp := *originalImplementation.SignUpPOST

                (*originalImplementation.SignUpPOST) = func(formFields []epmodels.TypeFormField, tenantId string, options epmodels.APIOptions, userContext supertokens.UserContext) (epmodels.SignUpPOSTResponse, error) {
                    email := ""
                    for _, v := range formFields {
                        if v.ID == "email" {
                            valueAsString, asStrOk := v.Value.(string)
                            if !asStrOk {
                                return epmodels.SignUpPOSTResponse{}, errors.New("Should never come here as we check the type during validation")
                            }
                            email = valueAsString
                        }
                    }
                    if emailNotAllowed(email) {
                        return epmodels.SignUpPOSTResponse{
                            GeneralError: &supertokens.GeneralErrorResponse{
                                Message: "You are not allowed to sign up. Please contact the app's admin to get permission",
                            },
                        }, nil
                    }
                    return originalSignUp(formFields, tenantId, options, userContext)
                }

                return originalImplementation
            },
        },
    })
}

func emailNotAllowed(email string) bool {
    // TODO: your impl to check email
    return true
}

from supertokens_python.recipe import emailpassword
from supertokens_python.recipe.emailpassword.interfaces import (
    APIInterface,
    SignUpPostOkResult,
    EmailAlreadyExistsError,
    SignUpPostNotAllowedResponse,
    APIOptions,
)
from supertokens_python.recipe.emailpassword.types import FormField
from typing import Any, Dict, Union, List
from supertokens_python.types import GeneralErrorResponse
from supertokens_python.recipe.session import SessionContainer


def override_apis(original_implementation: APIInterface):

    # first we copy the original implementation
    original_sign_up = original_implementation.sign_up_post

    async def sign_up(
        form_fields: List[FormField],
        tenant_id: str,
        session: Union[SessionContainer, None],
        should_try_linking_with_session_user: Union[bool, None],
        api_options: APIOptions,
        user_context: Dict[str, Any],
    ) -> Union[
        SignUpPostOkResult,
        EmailAlreadyExistsError,
        SignUpPostNotAllowedResponse,
        GeneralErrorResponse,
    ]:
        email = ""
        for i in range(len(form_fields)):
            if form_fields[i].id == "email":
                email = form_fields[i].value

        if is_not_allowed(email):
            return GeneralErrorResponse(
                message="You are not allowed to sign up. Please contact the app's admin to get permission"
            )

        return await original_sign_up(
            form_fields,
            tenant_id,
            session,
            should_try_linking_with_session_user,
            api_options,
            user_context,
        )

    original_implementation.sign_up_post = sign_up

    return original_implementation


def is_not_allowed(email: str):
    # TODO: your impl to check if the email is allowed
    return True


emailpassword.init(override=emailpassword.InputOverrideConfig(apis=override_apis))

Auth Methods

Add ons

Custom error response using `GENERAL_ERROR` status

Important