Dynamic Validation Messages Using Yup and Typescript

问题

I am trying to create some custom error messages with Yup to determine if the user's email address is in use.

I have created the following promise to try and catch a server communication error:

.test(
{
    name: 'Email Check',
    test: value => {
        if (value.includes("@")) {
            return new Promise<yup.ValidationError>((resolve, reject) => {
                let client = new RegistrationApi();
                client.emailCheck(value,
                    x => x ? resolve(undefined) : resolve(new yup.ValidationError("E-mail address already used", value, "")),
                    () =>resolve(new yup.ValidationError("Failed to contact server", value, "")),
                    undefined);
            });
        }
        else {
            return false;
        }
    }
}),

Returning the validation errors doesn't result in any error message being displayed. What am I doing wrong? I have tried to use the createError method which seems to be details in examples, but it doesn't seem to exist in this context.

回答1:

Regarding your code, you will want to reject your Promise and not resolve it.

generally; you need to return a promise to the validation function of your yup schema. Or you can write a specific async test.

回答2:

createError needs to be used inside of a function declaration for the test method. You are currently using an arrow function.

来源：https://stackoverflow.com/questions/60154861/dynamic-validation-messages-using-yup-and-typescript