Form validation (C# ASP MVC)

[Peter Morris]

Hi all

I come from the ASP MVC C# world.  Over there I can add the following to a view @Html.ValidationMessageFor(x => x.Name) and if there is an error in my view state for that field it will output error text

ViewState.AddError('Name', 'Required');

return View();

It will also re-populate the input values of the form.  I'm looking to achieve something similar with Express.  Keeping the form values and also validating input + showing errors against form inputs.  Any advice would be appreciated!

[Boris Yankov]

Express does not do anything like this. 
It is much 'lower level' and nimble, and this type of validation goes outside its scope.

[Peter Morris]

I am hoping for middleware suggestions. I like express-validator, but now I just need a suggestion on how to default input() values to what was posted (and null if it is a GET request).

[Peter Morris]

I created the following plugin....

exports = module.exports = function (req, res, next) {

    var body = req.body;

    if (typeof body === 'undefined') {

        return next(new Error('form-values must be used after body-parser'));

    }

    var bodyKeys = Object.keys(req.body);

    res.locals.fv = function (name, defaultValue) {

        if (bodyKeys.indexOf(name) === -1) {

            if (typeof defaultValue === 'undefined') {

                return '';

            } else {

                return defaultValue;

            }

        } else {

            return req.body[name];

        }

    }

    return next();

};

Then to use it

var formValues = require('./lib/form-values');

app.use(formValues);

In the view

input(name="username", value="#{fv('username')}", type="text")

You can also use #fv('fieldName', 32)

[Alexandre Laurent]

I've just made a module that helps with validation and rendering of your forms (https://github.com/shaoner/torti), it can be extended and used with express.

Any feedback is welcome! 

There is also https://github.com/freewil/express-form