Ktor Client

Ktor Client is a framework for building asynchronous client-side applications. Akkurate provides an integration to automatically validate downloaded data.

Installation

Before using Akkurate with Ktor, you need to add the following dependency to your Gradle script:

Add the Akkurate plugin for Ktor

implementation("dev.nesk.akkurate:akkurate-ktor-client:0.11.0")

Validate on deserialization

We want to retrieve the latest releases of Akkurate, using GitHub's API:

@Validate
@Serializable
data class Release(val name: String)

suspend fun main() {
    val client = HttpClient(CIO) {
        install(ContentNegotiation) {
            json(Json { ignoreUnknownKeys = true })
        }
    }

    val apiUrl = "https://api.github.com/repos/nesk/akkurate/releases"
    val response: HttpResponse = client.get(apiUrl)
    val data: List<Release> = response.body()
    println(data)
}

[
    Release(name=Akkurate 0.10.0),
    Release(name=Akkurate 0.9.1),
    Release(name=Akkurate 0.9.0), 
    ...
]

Although this API is probably well maintained, we fear potential issues on the API side, like bugs or breaking changes. To protect ourselves, we want to validate the response body:

val validateReleaseList = Validator<List<Release>> {
    each {
        name.isNotEmpty()
    }
}

And we register this validator in our client:

install(Akkurate) {
    registerValidator(validateReleaseList)
}

Now, when deserializing the response body, the Release instances are automatically validated, and an exception is thrown when invalid:

try {
    val data: List<Release> = response.body()
    println(data)
} catch (exception: ValidationResult.Exception) {
    System.err.println("Invalid response: ${exception.violations}")
}

Last modified: 19 December 2024