mirror of https://github.com/vapor/docs.git
107 lines
3.8 KiB
Markdown
107 lines
3.8 KiB
Markdown
---
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currentMenu: guide-validation
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---
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# Validation
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Vapor provides a few different ways to validate data coming into your application. Let's start by looking at the most common.
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## Common Usage
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Several useful convenience validators are included by default. You can use these to validate data coming into your application, or combine them and create your own.
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Let's look at the most common way to validate data.
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```swift
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class Employee {
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var email: Valid<Email>
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var name: Valid<Name>
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init(request: Request) throws {
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name = try request.data["name"].validated()
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email = try request.data["email"].validated()
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}
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}
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```
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Here we have a typical Employee model with an `email` and `name` property. By declaring both of these properties as `Valid<>`, you are ensuring that these properties can only ever contain valid data. The Swift type checking system will prevent anything that does not pass validation from being stored.
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To store something in a `Valid<>` property, you must use the `.validated()` method. This is available for any data returned by `request.data`.
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`Email` is a real `validator` included with Vapor, but `Name` is not. Let's take a look at how you can create a Validator.
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```swift
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Valid<OnlyAlphanumeric>
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Valid<Email>
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Valid<Unique<T>>
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Valid<Matches<T>>
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Valid<In<T>>
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Valid<Contains<T>>
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Valid<Count<T>>
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```
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## Validators vs. ValidationSuites
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Validators, like `Count` or `Contains` can have multiple configurations. For example:
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```swift
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let name: Valid<Count<String>> = try "Vapor".validated(by: Count.max(5))
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```
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Here we are validating that the `String` is at most 5 characters long. The type of `Valid<Count>` tells us that the string has been validated to be a certain count, but it does not tell us exactly what that count was. The string could have been validated to be less than three characters or more than one million.
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Because of this, `Validators` themselves are not as type safe as some applications might desire. `ValidationSuites` fix this. They combine multiple `Validators` and/or `ValidationSuites` together to represent exactly what type of data should be considered valid
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## Custom Validator
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Here is how to create a custom `ValidationSuite`.
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```swift
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class Name: ValidationSuite {
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static func validate(input value: String) throws {
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let evaluation = OnlyAlphanumeric.self
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&& Count.min(5)
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&& Count.max(20)
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try evaluation.validate(input: value)
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}
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}
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```
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You only have to implement one method. In this method, use any other validators or logic to create your custom validator. Here we are defining a Name as only accepting alphanumeric Strings that are between 5 and 20 characters.
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Now we can be sure that anything of type Valid<Name> follows these rules.
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## Combining Validators
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In the `Name` validator, you can see that `&&` is being used to combine validators. You can use `&&` as well as `||` to combine any validator as you would boolean values with an `if` statement.
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You can also use `!` to invert the validator.
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```swift
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let symbols = input.validated(by: !OnlyAlphanumeric.self)
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```
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## Testing Validity
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While `validated() throw` is the most common method for validating, there are two others.
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```swift
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let passed = input.passes(Count.min(5))
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let valid = try input.tested(Count.min(5))
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```
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`passes()` returns a boolean indicating whether or not the test passed. `tested()` will throw if the validation does not pass. But unlike `validated()` which returns a `Valid<>` type, `tested()` returns the original type of the item it was called on.
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## Validation Failures
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Vapor will automatically catch validation failures in the `ValidationMiddleware`. But you can catch them on your own, or customize responses for certain types of failures.
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```swift
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do {
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//validation here
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} catch let error as ValidationErrorProtocol {
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print(error.message)
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}
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```
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