Which frontend SDK do you use?

supertokens-web-js / mobile

supertokens-auth-react

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 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

import ThirdParty from "supertokens-node/recipe/thirdparty";
ThirdParty.init({    signInAndUpFeature: {        providers: [/* ... */]    },    override: {        functions: (oI) => {            return {                ...oI,                signInUp: async function (input) {                    if (emailNotAllowed(input.email)) {                        // this error will signal to the API to send a GENERAL_ERROR message                        throw new Error("Email not allowed");                    }                    return oI.signInUp(input);                }            }        },        apis: (oI) => {            return {                ...oI,                signInUpPOST: async function (input) {                    try {                        return oI.signInUpPOST!(input);                    } catch (err: any) {                        if (err.message === "Email not allowed") {                            return {                                status: "GENERAL_ERROR",                                message: "You are not allowed to sign up. Please contact the app's admin to get permission"                            }                        }                        throw err;                    }                }            }        }    }})
function emailNotAllowed(email: string) {    // TODO: your impl to check if email is allowed or not    return true;}

GoLang

import (    "errors"
    "github.com/supertokens/supertokens-golang/recipe/thirdparty"    "github.com/supertokens/supertokens-golang/recipe/thirdparty/tpmodels"    "github.com/supertokens/supertokens-golang/supertokens")
func main() {    thirdparty.Init(&tpmodels.TypeInput{        Override: &tpmodels.OverrideStruct{            Functions: func(originalImplementation tpmodels.RecipeInterface) tpmodels.RecipeInterface {                ogSignInUp := *originalImplementation.SignInUp
                (*originalImplementation.SignInUp) = func(thirdPartyID, thirdPartyUserID string, email string, userContext supertokens.UserContext) (tpmodels.SignInUpResponse, error) {                    if emailNotAllowed(email) {                        // this error will signal to the API to send a GENERAL_ERROR message                        return tpmodels.SignInUpResponse{}, errors.New("Email not allowed")                    }                    return ogSignInUp(thirdPartyID, thirdPartyUserID, email, userContext)                }                return originalImplementation            },            APIs: func(originalImplementation tpmodels.APIInterface) tpmodels.APIInterface {                ogSignInUpPOST := *originalImplementation.SignInUpPOST                (*originalImplementation.SignInUpPOST) = func(provider tpmodels.TypeProvider, code string, authCodeResponse interface{}, redirectURI string, options tpmodels.APIOptions, userContext supertokens.UserContext) (tpmodels.SignInUpPOSTResponse, error) {                    resp, err := ogSignInUpPOST(provider, code, authCodeResponse, redirectURI, options, userContext)                    if err != nil {                        if err.Error() == "Email not allowed" {                            return tpmodels.SignInUpPOSTResponse{                                GeneralError: &supertokens.GeneralErrorResponse{                                    Message: "You are not allowed to sign up. Please contact the app's admin to get permission",                                },                            }, nil                        }                        return tpmodels.SignInUpPOSTResponse{}, err                    }                    return resp, err                }                return originalImplementation            },        },    })}
func emailNotAllowed(email string) bool {    // TODO: your impl to check email    return true}

Python

from supertokens_python.recipe import thirdpartyfrom supertokens_python.recipe.thirdparty.interfaces import APIInterface, RecipeInterface, APIOptions, SignInUpPostOkResult, SignInUpPostNoEmailGivenByProviderResponse, SignInUpOkResultfrom supertokens_python.recipe.thirdparty.provider import Providerfrom typing import Any, Dict, Unionfrom supertokens_python.types import GeneralErrorResponse

def override_functions(original_implementation: RecipeInterface):    original_sign_in_up = original_implementation.sign_in_up
    async def sign_in_up(third_party_id: str, third_party_user_id: str, email: str,                         user_context: Dict[str, Any]) -> SignInUpOkResult:        if (is_not_allowed(email)):            # this error will signal to the API to send a GENERAL_ERROR message            raise Exception("Email not allowed")        return await original_sign_in_up(third_party_id, third_party_user_id, email, user_context)    original_implementation.sign_in_up = sign_in_up    return original_implementation

def override_apis(original_implementation: APIInterface):    # first we copy the original implementation    original_sign_in_up_post = original_implementation.sign_in_up_post
    async def sign_in_up_post(provider: Provider, code: str, redirect_uri: str, client_id: Union[str, None], auth_code_response: Union[Dict[str, Any], None], api_options: APIOptions,                              user_context: Dict[str, Any]) -> Union[SignInUpPostOkResult, SignInUpPostNoEmailGivenByProviderResponse, GeneralErrorResponse]:        try:            return await original_sign_in_up_post(provider, code, redirect_uri, client_id, auth_code_response, api_options, user_context)        except Exception as e:            if(str(e) == "Email not allowed"):                return GeneralErrorResponse(message="You are not allowed to sign up. Please contact the app's admin to get permission")            raise e
    original_implementation.sign_in_up_post = sign_in_up_post
    return original_implementation

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

thirdparty.init(    sign_in_and_up_feature=thirdparty.SignInAndUpFeature([]),    override=thirdparty.InputOverrideConfig(        apis=override_apis,        functions=override_functions    ))