Data annotation maxlength attribute (c# example)

In this example, I will show you to apply maxLength attribute to a string property in a class. You can set the maximum value for the property using data annotation validation property maxLength attribute. 

For example, I created column field Name with nvarchar(20) for the table UserLogin. Then, using entity framework I generated the class and applied validation for the name property in userlogin class. If the user enters the value more than the 20 characters, it will show a validation message. You can also customize the error message like below example.

Entity framework generated class: 

using System.ComponentModel.DataAnnotations;

    public partial class UserLogin
    {

      public int UserLoginID { get; set; }
      
        [MaxLength(20, ErrorMessage = "maximum {1} characters allowed")        
        public string Name { get; set; }
        public Nullable<System.DateTime> DOB { get; set; }
        public string Address { get; set; }
        public string Password { get; set; }
        public string Email { get; set; }
    } 

Razor View: 

@using (Html.BeginForm())
{
    @Html.ValidationSummary(true)
    <fieldset>
        <legend>UserLogin</legend>
 
        <div class="editor-label">
            @Html.LabelFor(model => model.Name)
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.Name, new { Class = "form-control" })
            @Html.ValidationMessageFor(model => model.Name)
        </div>
        <div class="editor-label">
            @Html.LabelFor(model => model.DOB)
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.DOB, new{id = "DOB", Class = "form-control"})
            @Html.ValidationMessageFor(model => model.DOB)
         </div>
       <div class="editor-label">
            @Html.LabelFor(model => model.Address)
        </div>
        <div class="editor-field">
            @Html.TextAreaFor(model => model.Address, new { Class = "form-control" })
            @Html.ValidationMessageFor(model => model.Address)
        </div>
 
        <div class="editor-label">
            @Html.LabelFor(model => model.Password)
        </div>
        <div class="editor-field">
            @Html.PasswordFor(model => model.Password, new { Class = "form-control box", type = "Password" })
            @Html.ValidationMessageFor(model => model.Password)
        </div>
 
        <div class="editor-label">
            @Html.LabelFor(model => model.Email)
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.Email, new { Class = "form-control" })
            @Html.ValidationMessageFor(model => model.Email)
        </div>

    </fieldset>

    <button type="submit" class="btn btn-success">Create</button>

}

 Asp.net data validation: