FLUENT VALIDATION

SARAVANAN SUBBURAYALJEEVAN TECHNOLOGIES

07-MAR-2013

Agenda

• Fluent Validation – Who am I?• Validator Creation• Built in Validators• Validator customizations• Localization support• Benefits• Conclusion

Fluent Validation – Who am I?

• Open source Validation library for .net• Uses Fluent interfaces and lambda expressions for

building validation rules• Source available in GitHub• Available as Nu-get packages– FluentValidation– FluentValidation.MVC3– FluentValidation.MVC4

• Signed binaries are also available

Validator Creation

• Validator class : AbstractValidator<>• Validation Result– IsValid– Errors

• Chaining Validators• Throwing Exceptions• Validators for Complex properties• Validators for Collections• Rule Sets

Built in Validators

• NotNull Validator• NotEmpty Validator• NotEqual Validator• Equal Validator• Length Validator• Less Than Validator

Built in Validators (contd.,)

• Less Than Or Equal Validator• Greater Than Validator• GreaterThan Or Equal Validator• Predicate Validator (aka Must)• RegEx Validator• Email Validator

Validator customizations

• Overriding the default error message– .WithMessage(“…”)

• Overriding the Default Property Name– .WithName(“Family name")

• Specifying a condition (When/Unless)– .When(Student.Age > 30)

• Cascading– .Cascade(CascadeMode.StopOnFirstFailure)

Localization support

• It supports the following languages:– English– French– German– Dutch– Spanish– Portuguese

Localization support (contd.,)

• Using Custom Resource Provider

• Messages must be public and static

Localization support (contd.,)

• Resource names that can be customizedemail_error equal_error exact_length_error exclusivebetween_errorgreaterthan_error greaterthanorequal_errorinclusivebetween_error length_errorlessthan_error lessthanorequal_errornotempty_error notequal_errornotnull_error predicate_errorregex_error

Benefits

• It separates validation from the Model• Unit testing is easier• Can perform different conditional validations

on different properties• Re-usability• No need for annotations (which make the

code looks clumsy)

DEMO

If (!Questions){ “THANK YOU!!!”;}