Consider a case when you have single model which is bind to multiple views. For example, UserInformation model bind to “Create” and “Edit” view. Now in “Create” view, I want to “Password” field as required but at the same time I want it to be optional on “Edit” view.
It means, In “Edit” view, If user provides “Password” then change it otherwise don’t update the “Password” field.
This is why it is important to create ViewModels, which gives you freedom to have different fields, validations etc for every view.
Now to achieve this goal in the given scenario, we need to make two tweaks.
Client Side
To disable client side validation, we need to disable it by force.
@Html.EditorFor(model => model.Password, new { htmlAttributes = new { @data_val = "false" , @class = "form-control"} })
Notice the @data_val= “false”. It will disable the validation on this field.
Server Side (In Action)
When the model is validated on the post action, ModelState.IsValid will always return false because password is not provided. Here we have to provide the current password to the model and Re-validate the model.
var userObj = db.Users_Info.Where(a => a.Id == users_Info.Id).FirstOrDefault();
if (String.IsNullOrEmpty(users_Info.Password))
{
users_Info.Password = userObj.Password;
}
ModelState.Clear();
TryValidateModel(users_Info);
Let me explain, first we retrieve current information saved in the database which we are using later to assign to current model if password is not provided. The last two lines actually reset the ModelState to return updated result on ModelState.IsValid.
Angry Coding 