MVC Tips : Implement IValidatableObject Interface for custom validation in ASP.Net MVC 4

Click Here to Download ImplementIValidateObjectInterfaceInMVC.zip Example.

We can validate model itself by implementing IValidatableObject Interface. For validation you need to implement 'Validate' method of IValidatableObject Interface.

Here is some difference from the attribute validation version.

• In this for validation method is 'Validate' instead of 'IsValid' and also return type and parameter is different.
• The return type for Validate is an IEnumerable<ValidationResult>, because the logic inside this method is validating the entire model and might need to return more than a single validation error.
• No parameter is passed to Validate because you  can directly access model properties because this Validate method is inside model.

Here is example for this.

.Net Tips : Attach and Raise events on XML document object with C#.Net and VB.Net example

You can attach events like 'onChanging' and 'onChanged' events on XML document object. These events raise when you 'ADD' or 'REMOVE' XML element from XML Document object.

First 'onChanging' event raise after that 'onChanged' event raise. In this event we get 'XObjectChangeEventArgs' class object. This object give us property like 'ObjectChange'. In this property we can know that which method is performed.

When we call 'Add' method we get 'Add' value in 'ObjectChange' property and when we call 'Remove' method we get 'Remove' value in 'ObjectChange' property.

Here is example on this.

MVC Tips : Custom Annotation validation in ASP.Net MVC 4

Click Here to Download CustomAnnotationInMVC.zip Example.

You can write your own custom annotations in MVC 4.
Here we can do custom validation using custom annotations. Custom annotations validation derive from the ValidationAttribute base class. This base class available in 'System.ComponentModel.DataAnnotations' namespace. ValidationAttribute class is abstract class.

For custom validation you need to write your own class and inherit ValidationAttribute class. After that, you need to override IsValid Method. IsValid Method has two parameters 'Value' and 'ValidationContext'.

• Value : Which contains your data, which is going to validate.
• ValidationContext : This parameter is very important. This content information like model object instance, model type friendly display name and other information

In this method you write your own logic for validate data and return result. If value is validate at that time you need to return this 'ValidationResult.Success' else you return result like 'return new ValidationResult(your custom error message)'