Explain Hidden files of client side strategies.

 Hidden Fields

• We can save data in hidden form fields and send it back in the next request.

• Sometimes we require some data to be stored on the client-side without displaying it on the page. Later when the user takes some action, we’ll need that data to be passed on to the server-side. This is a common scenario in many applications and hidden fields provide a good solution for this.

• Let’s add two methods in our WelcomeController:

[HttpGet]

public IActionResult SetHiddenFieldValue() {

User newUser = new User() {

Id = 101, Name = "John", Age = 31

};

return View(newUser);

}

[HttpPost]

public IActionResult SetHiddenFieldValue(IFormCollection keyValues) {

var id = keyValues["Id"];

return View();

}

• The GET version of the theSetHiddenValue() method creates a user object and passes that into the view.

• We use the POST version of the SetHiddenValue() method to read the value of a hidden field Id from FormCollection.

• In the View, we can create a hidden field and bind the Id value from Model:

◦ @Html.HiddenFor(model =>model.Id)

• Then we can use a submit button to submit the form:

◦ <input type="submit" value="Submit" />

• Now let’s run the application and navigate to /Welcome/SetHiddenFieldValue

• On inspecting the page source, we can see that a hidden field is generated on the page with the Id as the value: <input id="Id" name="Id" type="hidden" value="101">

• Now click the submit button after putting a breakpoint in the POST method. We can retrieve the Id value from the FormCollection.