Which UI do you use?

Custom UI

Pre built UI

Adding / Modifying field validators

Step 1: Front End

Now that you have added new fields to your signup form, let's see how you can add validators to make sure that your users provide the right information.

You can add a validate method to any formFields.

Building up on our previous example, let's add an age verification to our form:

ReactJS

// this goes in the auth route config of your frontend app (once the pre built UI script has been loaded)

(window as any).supertokensUIInit("supertokensui", {
    appInfo: {
        apiDomain: "...",
        appName: "...",
        websiteDomain: "..."
    },
    recipeList: [
        (window as any).supertokensUIEmailPassword.init({
            signInAndUpFeature: {
                signUpForm: {
                    formFields: [{
                        id: "name",
                        label: "Full name",
                        placeholder: "First name and last name"
                    }, {
                        id: "age",
                        label: "Your age",
                        placeholder: "How old are you?",
                        optional: true,

                        /* Validation method to make sure that age is above 18 */
                        validate: async (value) => {
                            if (parseInt(value) > 18) {
                                return undefined; // means that there is no error
                            }
                            return "You must be over 18 to register";
                        }

                    }, {
                        id: "country",
                        label: "Your country",
                        placeholder: "Where do you live?",
                        optional: true
                    }]
                }
            }
        }),
        (window as any).supertokensUISession.init()
    ]
});

Angular

import SuperTokens from "supertokens-auth-react";
import EmailPassword from "supertokens-auth-react/recipe/emailpassword";
import Session from "supertokens-auth-react/recipe/session";

SuperTokens.init({
    appInfo: {
        apiDomain: "...",
        appName: "...",
        websiteDomain: "..."
    },
    recipeList: [
        EmailPassword.init({
            signInAndUpFeature: {
                signUpForm: {
                    formFields: [{
                        id: "name",
                        label: "Full name",
                        placeholder: "First name and last name"
                    }, {
                        id: "age",
                        label: "Your age",
                        placeholder: "How old are you?",
                        optional: true,

                        /* Validation method to make sure that age is above 18 */
                        validate: async (value) => {
                            if (parseInt(value) > 18) {
                                return undefined; // means that there is no error
                            }
                            return "You must be over 18 to register";
                        }

                    }, {
                        id: "country",
                        label: "Your country",
                        placeholder: "Where do you live?",
                        optional: true
                    }]
                }
            }
        }),
        Session.init()
    ]
});

Vue

// this goes in the auth route config of your frontend app (once the pre built UI script has been loaded)

(window as any).supertokensUIInit("supertokensui", {
    appInfo: {
        apiDomain: "...",
        appName: "...",
        websiteDomain: "..."
    },
    recipeList: [
        (window as any).supertokensUIEmailPassword.init({
            signInAndUpFeature: {
                signUpForm: {
                    formFields: [{
                        id: "name",
                        label: "Full name",
                        placeholder: "First name and last name"
                    }, {
                        id: "age",
                        label: "Your age",
                        placeholder: "How old are you?",
                        optional: true,

                        /* Validation method to make sure that age is above 18 */
                        validate: async (value) => {
                            if (parseInt(value) > 18) {
                                return undefined; // means that there is no error
                            }
                            return "You must be over 18 to register";
                        }

                    }, {
                        id: "country",
                        label: "Your country",
                        placeholder: "Where do you live?",
                        optional: true
                    }]
                }
            }
        }),
        (window as any).supertokensUISession.init()
    ]
});

Here is what happens if someone tries to register with an age of 17:

Security

Front-end validation is great for user experience but you should always make sure that you are also applying these validations on the backend.

Step 2: Back End

In your backend's SuperTokens init method, let's replicate the validate functions from above:

NodeJS

Important

For other backend frameworks, you can follow our guide on how to spin up a separate server configured with the SuperTokens backend SDK to authenticate requests and issue session tokens.

GoLang

import SuperTokens from "supertokens-node";
import EmailPassword from "supertokens-node/recipe/emailpassword";
import Session from "supertokens-node/recipe/session";

SuperTokens.init({
    appInfo: {
        apiDomain: "...",
        appName: "...",
        websiteDomain: "..."
    },
    supertokens: {
        connectionURI: "...",
    },
    recipeList: [
        EmailPassword.init({
            signUpFeature: {
                formFields: [{
                    id: "name"
                }, {
                    id: "age",
                    /* Validation method to make sure that age >= 18 */
                    validate: async (value, tenantId) => {
                        if (parseInt(value) >= 18) {
                            return undefined; // means that there is no error
                        }
                        return "You must be over 18 to register";
                    }
                }, {
                    id: "country",
                    optional: true
                }]
            }
        }),
        Session.init({
        })
    ]
});

Python

import (
    "strconv"

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

func main() {
    countryOptional := true
    supertokens.Init(supertokens.TypeInput{
        RecipeList: []supertokens.Recipe{
            emailpassword.Init(&epmodels.TypeInput{
                SignUpFeature: &epmodels.TypeInputSignUp{
                    FormFields: []epmodels.TypeInputFormField{
                        {
                            ID: "name",
                        },
                        {
                            ID: "age",
                            Validate: func(value interface{}, tenantId string) *string {
                                age, _ := strconv.Atoi(value.(string))
                                if age >= 18 {
                                    // return nil to indicate success
                                    return nil
                                }
                                err := "You must be over 18 to register"
                                return &err
                            },
                        },
                        {
                            ID:       "country",
                            Optional: &countryOptional,
                        },
                    },
                },
            }),
        },
    })
}

Other Frameworks

from supertokens_python import init, InputAppInfo
from supertokens_python.recipe import emailpassword
from supertokens_python.recipe.emailpassword import InputFormField
from typing import Any

async def validate_age(value: Any, tenant_id: str):
    # Validation method to make sure that age >= 18
    if int(value) >= 18:
        return None # means that there is no error
    return 'You must be over 18 to register'

init(
    app_info=InputAppInfo(api_domain="...", app_name="...", website_domain="..."),
    
    framework='...', 
    recipe_list=[
        emailpassword.init(
            sign_up_feature=emailpassword.InputSignUpFeature(
                form_fields=[
                    InputFormField(id='name'),
                    InputFormField(id='age', validate=validate_age),
                    InputFormField(id='country', optional=True)
                ]
            )
        )
    ]
)

Multi Tenancy

Notice the tenantId argument passed into the validate function. Using that, you can define custom logic per tenant. For example, you can define different password policies for different tenants.

Changing the default email and password validators

By default, SuperTokens adds an email and a password validator to the sign-up form.

• The default email validator makes sure that the provided email is in the correct email format.
• The default password validator makes sure that the provided password:
  • has a minimum of 8 characters.
  • contains at least one lowercase character
  • contains at least one number

important

• The email validator that you define for Sign up is also applied automatically to Sign In.
• The password validator that you define for Sign up is also applied automatically to reset password forms.

Step 1: Front End

ReactJS

// this goes in the auth route config of your frontend app (once the pre built UI script has been loaded)

(window as any).supertokensUIInit("supertokensui", {
    appInfo: {
        apiDomain: "...",
        appName: "...",
        websiteDomain: "..."
    },
    recipeList: [
        (window as any).supertokensUIEmailPassword.init({
            signInAndUpFeature: {
                signUpForm: {
                    formFields: [{
                        id: "email",
                        label: "...",
                        validate: async (value) => {
                            // Your own validation returning a string or undefined if no errors.
                            return "...";
                        }
                    }, {
                        id: "password",
                        label: "...",
                        validate: async (value) => {
                            // Your own validation returning a string or undefined if no errors.
                            return "...";
                        }
                    }]
                }
            }
        })
    ]
});

Angular

import SuperTokens from "supertokens-auth-react";
import EmailPassword from "supertokens-auth-react/recipe/emailpassword";

SuperTokens.init({
    appInfo: {
        apiDomain: "...",
        appName: "...",
        websiteDomain: "..."
    },
    recipeList: [
        EmailPassword.init({
            signInAndUpFeature: {
                signUpForm: {
                    formFields: [{
                        id: "email",
                        label: "...",
                        validate: async (value) => {
                            // Your own validation returning a string or undefined if no errors.
                            return "...";
                        }
                    }, {
                        id: "password",
                        label: "...",
                        validate: async (value) => {
                            // Your own validation returning a string or undefined if no errors.
                            return "...";
                        }
                    }]
                }
            }
        })
    ]
});

Vue

// this goes in the auth route config of your frontend app (once the pre built UI script has been loaded)

(window as any).supertokensUIInit("supertokensui", {
    appInfo: {
        apiDomain: "...",
        appName: "...",
        websiteDomain: "..."
    },
    recipeList: [
        (window as any).supertokensUIEmailPassword.init({
            signInAndUpFeature: {
                signUpForm: {
                    formFields: [{
                        id: "email",
                        label: "...",
                        validate: async (value) => {
                            // Your own validation returning a string or undefined if no errors.
                            return "...";
                        }
                    }, {
                        id: "password",
                        label: "...",
                        validate: async (value) => {
                            // Your own validation returning a string or undefined if no errors.
                            return "...";
                        }
                    }]
                }
            }
        })
    ]
});

Step 2: Back End

NodeJS

Important

For other backend frameworks, you can follow our guide on how to spin up a separate server configured with the SuperTokens backend SDK to authenticate requests and issue session tokens.

GoLang

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

SuperTokens.init({
    appInfo: {
        apiDomain: "...",
        appName: "...",
        websiteDomain: "..."
    },
    supertokens: {
        connectionURI: "...",
    },
    recipeList: [
        EmailPassword.init({
            signUpFeature: {
                formFields: [{
                    id: "email",
                    validate: async (value, tenantId) => {
                        // Your own validation returning a string or undefined if no errors.
                        return "...";
                    }
                }, {
                    id: "password",
                    validate: async (value, tenantId) => {
                        // Your own validation returning a string or undefined if no errors.
                        return "...";
                    }
                }]
            }
        }),
    ]
});

Python

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

func main() {
    supertokens.Init(supertokens.TypeInput{
        RecipeList: []supertokens.Recipe{
            emailpassword.Init(&epmodels.TypeInput{
                SignUpFeature: &epmodels.TypeInputSignUp{
                    FormFields: []epmodels.TypeInputFormField{
                        {
                            ID: "email",
                            Validate: func(value interface{},  tenantId string) *string {
                                // Your own validation returning a string or nil if no errors.
                                return nil
                            },
                        },
                        {
                            ID: "password",
                            Validate: func(value interface{},  tenantId string) *string {
                                // Your own validation returning a string or nil if no errors.
                                return nil
                            },
                        },
                    },
                },
            }),
        },
    })
}

Other Frameworks

from supertokens_python import init, InputAppInfo
from supertokens_python.recipe import emailpassword
from supertokens_python.recipe.emailpassword import InputFormField
from typing import Any

async def validate_password(value: Any, tenant_id: str):
    pass # TODO

async def validate_email(value: Any, tenant_id: str):
    pass # TODO

init(
    app_info=InputAppInfo(api_domain="...", app_name="...", website_domain="..."),
    framework='...', 
    recipe_list=[
        emailpassword.init(
            sign_up_feature=emailpassword.InputSignUpFeature(
                form_fields=[
                    InputFormField(id='password', validate=validate_password),
                    InputFormField(id='email', validate=validate_email)
                ]
            )
        )
    ]
)