https://github.com/viartemev/ktor-validation-feature
Ktor validation feature
https://github.com/viartemev/ktor-validation-feature
kotlin ktor ktor-feature ktor-framework ktor-server validation
Last synced: 8 months ago
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Ktor validation feature
- Host: GitHub
- URL: https://github.com/viartemev/ktor-validation-feature
- Owner: viartemev
- Created: 2019-12-24T12:55:51.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2019-12-25T12:37:29.000Z (over 6 years ago)
- Last Synced: 2025-04-02T13:21:42.531Z (about 1 year ago)
- Topics: kotlin, ktor, ktor-feature, ktor-framework, ktor-server, validation
- Language: Kotlin
- Homepage:
- Size: 69.3 KB
- Stars: 5
- Watchers: 2
- Forks: 0
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
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README
# Ktor validation feature
[](https://travis-ci.com/viartemev/ktor-validation-feature)
Validation is an important part of each API. This feature provides a simple way for incoming request validation.
Let's imagine we have request object which must be validated:
```kotlin
data class Message(val id: Long, val message: String)
```
First of all, we need to implement validation logic implementing `Validator` interface:
```kotlin
object MessageValidator : Validator {
override fun supports(clazz: KClass<*>): Boolean = Message::class == clazz
override fun validate(obj: Message): ValidationResult {
val errors = mutableMapOf>()
if (obj.message.isBlank()) errors["message"] = listOf("message must be not blank")
return ValidationResult.Invalid(errors.toMap())
}
}
```
Then we need to configure the feature. There are 2 options:
1. If object validation fails (object is not valid), then we get `RequestValidationException`, which we need handle.
One of the options is StatusPage feature.
```kotlin
install(ValidationFeature) {
validators = listOf(MessageValidator) //add MessageValidator to feature
}
//StatusPages feature is optional, otherwise you should care about exception handling by yourself
install(StatusPages) {
exception { cause ->
call.respond(HttpStatusCode.BadRequest, cause.validationResult)
}
}
// Some logic is here
post("/messages") {
val message = call.receive()
call.respond(message)
}
```
2. If you don't want to throw the exception, you should set `throwExceptionIfInvalid` to `false`.
In this case, you could get validation result by calling: `call.receiveValidated()` which returns `Pair`.
`ValidationResult` is sealed class, can be:
- `NotValidated` - in case validators weren't provided
- `Valid` - in case validation finished successfully
- `Invalid` - in case validation failed
```kotlin
install(ValidationFeature) {
validators = listOf(MessageValidator) //add MessageValidator to feature
throwExceptionIfInvalid = false //by default, it is true
}
post("/messages") {
val (msg, validatedResult) = call.receiveValidated()
when (validatedResult) {
is ValidationResult.NotValidated -> call.respond(msg.message)
is ValidationResult.Valid -> call.respond(msg)
is ValidationResult.Invalid -> call.respond(HttpStatusCode.BadRequest, validatedResult.errors)
}
}
```
### Improvements
Add validated function for Routers
```kotlin
post("/") = validated {
val (msg, validatedResult) = call.receiveValidated()
when (validatedResult) {
is ValidationResult.NotValidated -> call.respond(msg.message)
is ValidationResult.Valid -> call.respond(msg)
is ValidationResult.Invalid -> call.respond(HttpStatusCode.BadRequest, validatedResult.errors)
}
}
```