# Validation **Structr.AspNetCore.Validation** package contains number of attributes supplying a wide range of developer's basic needs in validating user-input data in [ASP.NET Core](https://docs.microsoft.com/en-us/aspnet/core/introduction-to-aspnet-core) application. Everything is done in classic manner by specifying validation attributes for properties to be validated. Every attribute generates it's own but fully customizable error message. More to say - validation attributes could be combined between each other when you need it. Inspiration for creating this package was found in validation package for ASP.NET MVC - [Foolproof](https://github.com/leniel/foolproof) and ASP.NET Core fork - [Foolproof.Core](https://github.com/rpgkaiser/FoolProof.Core). ## Installation AspNetCore.Validation package is available on [NuGet](https://www.nuget.org/packages/Structr.AspNetCore.Validation/). ``` dotnet add package Structr.AspNetCore.Validation ``` ## Setup Setup validation services in your ASP.NET Core application: ```csharp services.AddAspNetCoreValidation(); ``` ## Usage Add validation attributes for your models. For example: ```csharp public class AddUserViewModel { public string FullName { get; set; } public bool IsEmployee { get; set; } [RequiredIf(nameof(IsEmployee), true, ErrorMessage = "Employee must have some role.")] public IEnumerable RolesIds { get; set; } public DateTime? ActiveFrom { get; set; } [GreaterThanOrEqualTo(nameof(ActiveFrom), PassOnNull = true)] public DateTime? ActiveTo { get; set; } } ``` And check `ModelState.IsValid` property in controller action: ```csharp [HttpPost] public IActionResult AddUser(AddUserViewModel addUserViewModel) { if (ModelState.IsValid == false) { return View(addUserViewModel); } /* Some logic here */ return RedirectToAction("Index"); } ``` List of properties that are available in each validation attribute: | Property name | Description | | ---------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------- | | `RelatedProperty` | Value of the related property with which the value of validating property will be compared. | | `RelatedPropertyDisplayName` | Display name of the related property with which value the value of validating property will be compared. Will be used in error message if validation fails. | | `ErrorMessage` | An error message to associate with a validation control if validation fails. | | `ErrorMessageResourceName` | The error message resource name to use in order to look up the `ErrorMessageResourceType` property value if validation fails. | | `ErrorMessageResourceType` | The resource type to use for error-message lookup if validation fails. | So all attributes allow to specify custom error messages and get them from resource files if needed. ### Simple validation These attributes allow to specify related property which value will be used to check value of marked property. | Attribute name | Description | | -------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `EqualTo` | Specifies that a data field value must be equal to a value of specified related property. | | `NotEqualTo` | Specifies that a data field value must NOT be equal to a value of specified related property. | | `GreaterThan` | Specifies that a data field value must be greater than a value of specified related property. | | `GreaterThanOrEqual` | Specifies that a data field value must be greater or equal to a value of specified related property. | | `LessThan` | Specifies that a data field value must be less than a value of specified related property. | | `LessThanOrEqualTo` | Specifies that a data field value must be less or equal to a value of specified related property. | | `In` | Specifies that a data field value must be contained in value of specified related property. In case of array-type of related property simple inclusion will be checked. If it's not an array-type the equality operator will be used. | | `NotIn` | Specifies that a data field value must NOT be contained in value of specified related property. In case of array-type of related property simple inclusion will be checked. If it's not an array-type the equality operator will be used. | | `Is` | The generalized version of those above. Specifies that a data field value must match a value of specified related property. This one needs a matching `Operator` to be specified. | In addition to properties available for all validation attributes, attributes of this type has `PassOnNull`. This property indicates that validation should be passed if value of property to be validated or value of related property equals `null`. In case of both values are `null` then the behavior of validation will depend on type of attribute. `GreaterThan`, `LessThan`, `NotIn` and `NotEqualTo` will fail validation. Others will succeed. ### Requirements These allow to make marked property requirement as conditional and based on related property value. | Attribute name | Description | | ------------------------- | ------------------------------------------------------------------------------------------- | | `RequiredIfEmpty` | Marks property as required when related property is empty. | | `RequiredIfNotEmpty` | Marks property as required when related property is NOT empty. | | `RequiredIfTrue` | Marks property as required when related property equals `true`. | | `RequiredIfFalse` | Marks property as required when related property equals `false`. | | `RequiredIfRegExMatch` | Marks property as required when related property matches provided regular expression. | | `RequiredIfNotRegExMatch` | Marks property as required when related property DOESN'T match provided regular expression. | | `RequiredIf` | The generalized version of attributes above. | ### Regular expressions The last one is `RegularExpressionIf` attribute which allows to check that a data field value must match the specified regular expression but only when related property has specified value. ```csharp public class FooViewModel { [RegularExpressionIf("[A-Z][a-z]\\d", nameof(Bar), true)] public string Foo { get; set; } public bool Bar { get; set; } } ``` This one will validate `Foo` property to match `[A-Z][a-z]\d` expression only if `Bar` property will be `true`. ## Client Use AspNetCore.Validation JavaScript files on client side with [jQuery validation plugin](https://github.com/jquery-validation/jquery-validation): Client scripts: | Script name | Description | | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------- | | [aspnetcore.validation.js](https://github.com/askalione/Structr/blob/master/src/Structr.AspNetCore.Validation/StaticFiles/aspnetcore.validation.js) | Basic client validation functions. | | [aspnetcore.jquery.validation.js](https://github.com/askalione/Structr/blob/master/src/Structr.AspNetCore.Validation/StaticFiles/aspnetcore.jquery.validation.js) | Adapters for jQuery validation plugin. | | [aspnetcore.validation.unobtrusive.js](https://github.com/askalione/Structr/blob/master/src/Structr.AspNetCore.Validation/StaticFiles/aspnetcore.validation.unobtrusive.js) | Adapters for unobtrusive. | ```html ``` **Important:** Order of includes client scripts is required!