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

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;
                    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 (    "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, options epmodels.APIOptions, userContext supertokens.UserContext) (epmodels.SignUpPOSTResponse, error) {                    email := ""                    for _, v := range formFields {                        if v.ID == "email" {                            email = v.Value                        }                    }                    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, options, userContext)                }
                return originalImplementation            },        },    })}
func emailNotAllowed(email string) bool {    // TODO: your impl to check email    return true}

from supertokens_python.recipe import emailpasswordfrom supertokens_python.recipe.emailpassword.interfaces import APIInterface, SignUpPostOkResult, SignUpPostEmailAlreadyExistsError, APIOptionsfrom supertokens_python.recipe.emailpassword.types import FormFieldfrom typing import Any, Dict, Union, Listfrom supertokens_python.types import GeneralErrorResponse

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],                      api_options: APIOptions, user_context: Dict[str, Any]) -> Union[SignUpPostOkResult, SignUpPostEmailAlreadyExistsError, 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, 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    ))