如何从 Joi 中已定义的架构 object 中访问/提取架构？

Question

I have this schema defined.

    schema = Joi.object({
        username: Joi.string().min(5).max(32).required().label('Username'),
        password: Joi.string().min(8).max(50).required().label('Password')
    });

I know that I need to pass both valid username and password values to get no errors.

But, I need to validate only one field at a time against this schema. this means, if I pass a valid username, I want this schema to return no errors.

Here is what I have done:

validateOneField(name, value){
    // create an object  dynamically
    const obj = { [name] : value };
    // here I need to get the schema for either username or password depending upon name argument.
    // how can I create a schema dynamically here?
    // example:
    const schema = Joi.object({ this.schema[name] }); // I know this won't work!
    // and validate only single value
    const { error } = schema.validate(obj);
    console.log(error);
}

Is there any other way to access the schema like: this.schema[username] or this.schema[password]?

Thank you in advance!

Answer 1

You can use the extract method to get the rule you want

validateOneField(name, value){
    const rule = this.schema.extract(name);
    const { error } = rule.validate(value);
    console.log(error);
}

Answer 2

With the help of Gabriele Petrioli's answer I was able to get this done.

Code:

    validateProperty = ({name, value}) => {
        const obj = { [name] : value };
        const rule = this.schema.extract(name);
        const schema = Joi.object({ [name] : rule});
        const { error } = schema.validate(obj);
        return (!error) ? null : error.details[0].message;
    };

Thank You Guys!