Validation Rules

When a service command (link here) that accepts parameters (ids or DTOs) is invoked, those parameters are subjected to validation rules. Validation rules are generally considered to be general rules about the data itself, such as field required rules, field length rules, etc.

Peasy supports easy validation integrity checks by applying your DTO properties with validation attributes. You can apply your properties with any of the validation rules exposed in the System.ComponentModel.DataAnnotations assembly, or create your own validation attributes, as long as they inherit from System.ComponentModel.DataAnnotations.ValidationAttribute. More information on creating custom validation attributes can be found here.

Here's a sample DTO with validation attributes applied:

    using System.ComponentModel.DataAnnotations;
   
    public class Person : Peasy.Core.IDomainObject<int>
    {
        public int ID { get; set; }
        [Required]
        [StringLength(20)]
        public string Name { get; set; }
        [Required]
        public int Age { get; set; }
        public string City { get; set; }
    }

In this example, any Person DTO passed to an InsertCommand (link) or UpdateCommand (link) via a service (link) will pass validation only if the value for Person.Name is supplied and the length is less than or equal to 20 characters.

Unfortunately, in the above example, not supplying Name with a value will still allow validation to pass, even though it is applied with the Required attribute. This is due to a limitation of the Required Attribute itself, and will also pass when applied to non-generic numeric properties (Int, Decimal, etc.) whose values are not set. To address this limitation, Peasy offers the PeasyRequiredAttribute.

Peasy Validation Attributes

Peasy offers the PeasyRequiredAttribute which when applied to string, DateTime, and non-generic numeric properties (Int, Decimal, etc.), validation will fail when these values are not set.

Here's an example:

    using System.ComponentModel.DataAnnotations;
   
    public class Person : Peasy.Core.IDomainObject<int>
    {
        public int ID { get; set; }
        [PeasyRequired]
        public string Name { get; set; }
        [PeasyRequired]
        public int Age { get; set; }
        [PeasyRequired]
        public DateTime BirthDate { get; set; }
    }

In this example, any Person DTO passed to an InsertCommand (link) or UpdateCommand (link) via a service (link) will pass validation only if the values are set for Person.Name and Person.Age and Person.BirthDate are set with non-empty string, non-zero, and non-default date values, respectively.