c# - validate age according to date of birth using model in mvc 4

Question

I have registration form and its contain date of birth field.

Using calender date picker its input the value to this field.

these are the steps to insert value for this field

step 1

step 2

step 3

so its taking values in dd/MM/yyyy format

This is appearance of date of birth field in my model class

[DisplayName("Date of Birth")]
[DataType(DataType.Date), DisplayFormat(DataFormatString = "{0:dd/MM/yyyy}", ApplyFormatInEditMode = true)]
public Nullable<System.DateTime> Date_of_Birth { get; set; }

This is appearance of date of birth field in my view file

   <div class="form-group"> 
   <div class="editor-label">
        @Html.LabelFor(model => model.Date_of_Birth)
        @Html.Label("*", new { id="star" , @class = "requiredFiledCol" })
   </div>
   <div class="editor-field">
        @Html.TextBoxFor(model => model.Date_of_Birth, "{0:dd/MM/yyyy}", new { @class = "form-control datepicker", placeholder = "DD/MM/YYYY" , maxlength="100" })
        @Html.ValidationMessageFor(model => model.Date_of_Birth)
    </div>
    </div>

I want to do client side validation for data of birth field . show error message when input filed is not in this range 100>Age>18

whats the approach I should take ?

Answer 1

Well since you are already using data annotations why not make your own. do this:

create a class in an dll that you use or make a new one and at a minimum add the following code to it

public class MinimumAgeAttribute: ValidationAttribute
{
    int _minimumAge;

    public MinimumAgeAttribute(int minimumAge)
    {
      _minimumAge = minimumAge;
    }

    public override bool IsValid(object value)
    {
        DateTime date;
        if (DateTime.TryParse(value.ToString(),out date))
        {
            return date.AddYears(_minimumAge) < DateTime.Now;
        }

        return false;
    }
}

then in your view model do this:

[MinimumAge(18)]
[DisplayName("Date of Birth")]
[DataType(DataType.Date), DisplayFormat(DataFormatString = "{0:dd/MM/yyyy}", ApplyFormatInEditMode = true)]
public Nullable<System.DateTime> Date_of_Birth { get; set; }

or your web page you will have no issues as the framework(s) you use will pick it up. Without changing the ErrorMessage property in your class you will get something like

The field "{0}" is not valid.

The {0} is replaced by the property name or display name attribute that you gave the property in your model.

Hope it works for you.

Walter ps: make sure in the controller you do

if (ModelState.IsValid)
{
 ....
}