API based Custom FormValidation using SemanticUI/Jquery

In the last post, we discussed on how to implement form validation and subsequent submit using the Semantic UI and JQuery. In this follow up post, we discuss how we can enhance the validation capabilities further, by having a custom validation that depends on an external API call.

For the sake of example, let’s focus on an mock User Sign Up page, where we would be checking if the username exists prior to form submit.

Let’s write down our basic form first.

<form class="ui form" method='post' id="RegisterUser">
  <h4 class="ui dividing header">User Sign Up</h4>
  <div class="field">
    <div class="two fields">
      <div class="eight wide field">
        <label>UserName</label>
        <input type="text" placeholder="Username" id="username">
      </div>
    </div>
  </div>
  <button class="ui button" tabindex="0">Sign Up</button>
  <div class="ui hidden negative message" id="formresult"></div>
  <div class="ui error message" id="formvalidation"></div>
</form>

Now, let’s create our Validation Script.

var formvalidationrules = {
    on: 'submit',
    fields: {
      username: {
        identifier: 'username',
        rules: [{
          type: 'custom',
          prompt: 'username already exists'
        }]
      },
    },
    onSuccess: function(event) {
      event.preventDefault();
    }
  };

  $('#RegisterUser').form(formvalidationrules);

As you can see, the rule type has been specified as ‘custom’. The next obvious task is to write down the method to do the custom validation itself.

$.fn.form.settings.rules.custom = function() {
    var result;
    $.ajax({
      type: 'POST',
      url: '/echo/html/',
      async: false,
      data: {
        'html': $('#username').val()
      },
      success: function(data) {
        result = !(data == 'test');

      },
    });
    return result;

  };

Couple of things to note here.
a) The rule method has been added to form.settings.rules.
b) Now this is very important, your ajax calls needs to be synchronous.

That’s it, you are ready to roll. Check out the script in action in Fiddle Link

Form Validation and Submit using Semantic UI and JQuery

Bootstrap, despite all the effort to make it easily understandable, always relied heavily on its short hand notations for css classes. This seemed okay, until Semantic UI entered the race with its near perfect usage of natural language. The fact that it is well integrated with jQuery makes it a good choice for web developers.

One of the most common tasks in any web development has to do with form. The following code illustrates how to validate the form and submit it using the Semantic UI APIs.

 

                <form class="ui large form" method="POST" role="form" id="ValidateUser">
                    <section class="ui stacked segment">
                        <div class="field">
                            <div class="ui left icon input">
                                <i class="user icon"></i>
                                @Html.TextBoxFor(a => a.UserName, new { placeholder = "UserName",id="username" })
                                @Html.ValidationMessageFor(a => a.UserName)
                            </div>
                        </div>
                        <div class="field">
                            <div class="ui left icon input">
                                <i class="lock icon"></i>
                                @Html.PasswordFor(a => a.Password, new { placeholder = "Password",id="password" })
                                @Html.ValidationMessageFor(a => a.Password)
                            </div>
                        </div>

                        <input id="submitbutton" class="ui submit fluid large green button" type="submit" value="Login"/> 
                        <!-- <div class="ui blue submit button">Submit</div> -->
                        <div class="ui hidden negative message" id="formresult"></div>
                        <div class="ui error message" id="formvalidation"></div>
                    </section>
                </form>
$(document).ready(function () {

            var urllink = '@Url.Action("Login", "Validation")';


            $('#ValidateUser').form(
                                     {
                                         on: 'blur',
                                         fields: {
                                             username: {
                                                 identifier: 'username',
                                                 rules: [{
                                                     type: 'empty',
                                                     prompt: 'Username cannot be empty'
                                                 }]
                                             },
                                             password: {
                                                 identifier: 'password',
                                                 rules: [{
                                                     type: 'empty',
                                                     prompt: 'Password cannot be emtpy'
                                                 }]
                                             }
                                         },
                                         onSuccess: function (event) {
                                             $('#formresult').hide();
                                             $('#formresult').text('');
                                             event.preventDefault();
                                             return false;
                                         }

                                     }
                                   )
                                 .api({
                                     url: urllink,
                                     method:'POST',
                                     serializeForm: true,
                                     data: new FormData(this),
                                     onSuccess: function (result) {
                                        $('#formresult').show();
                                        if (result.Success) {
                                            window.location = "/Dashboard/Dashboard";
                                        }
                                        else {

                                            $('#formresult').append(result.Msg);
                                        }
                                        return false;
                                    }
                    });


        });

Fix CORS in Firefox

CORS is a hated word anyone working on Web Solutions might have encountered if your website is accessing another website or API. So how do you ensure your website is able to the required URL ?

The first and easiest fix would be to include “Access Control” headers in your web.config.


<httpProtocol>
 <customHeaders>
 <add name="Access-Control-Allow-Origin" value="*" />
 </customHeaders>
 </httpProtocol>

That should be it for every other browser except for Firefox, particularly if you are accessing a Restful Web API. By default, Firefox assumes the Request to have “Accept” Header as “application/xml“. This can be demonstrated once your fire up your Web API in Firefox Extension RestClient.

The workaround for the problem lies in changing the “Accept” header to “application/json”.