Automatic POST requests validator Express

I’m using express-validator and I’m trying to create a middleware that applies to every post request, finds the right validator for the request and calls the right method for the validation.
The validators are objects, exported from files in the /validators folder, the names of the files are related to the requests so that the validation midlleware can import the right validator from the request’s path (ex: the validator for the post to /auth/checkSignup is the file /validators/auth.js);
each validator has one (or more) validation method called ‘check’ where actionName is a part of the request’s path (in the example above ‘checkSignup’ is the action, so the AuthValidator has the method checkLogin).

ex of thw middleware called in the app.js file:

app.post(
    '*',
    ValidationDispatcher.validationMiddleware
);

the middleware should read the req.path and find the appropriate validator for the route (eg: the pathg is /auth/signup the validator is the one exported by the file auth.js, leaving out the folders), after that it should find the appropriate method (in the example above, the method is checkSignup); every method for the validation is similar to this:

checkSignup() {
        return expressValidator.checkSchema({
            email: {
                ...this.baseEmailSchema,
                custom: {
                    options: (value) => {
                        return UsersController.getByEmail(value).then((res) => {
                            return res != null;
                        });
                    },
                    errorMessage: "user with this email already exists",
                },
            },
            password: this.basePasswordSchema,
            confirmPassword: {
                custom: {
                    options: (value, { req }) => {
                        return value === req.body.password;
                    },
                    errorMessage: "passwords have to match",
                },
            },
        });
    }

but with this approach I’m returning a middleware that will not be executed;
does anyone have any ideas?