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Uploading files


Apollo Kotlin supports file uploads via the GraphQL multipart request specification.

First, add the following custom scalar mapping to the Apollo Gradle plugin configuration:

build.gradle[.kts]
apollo {
mapScalarToUpload("Upload")
}

In this example, the GraphQL schema defines a custom scalar type named Upload. You can use a different name as needed for your schema.

Note: You don't need to register a type adapter for Upload, because the mapScalarToUpload method registers it automatically.

Now let's consider a mutation that takes an Upload as a parameter:

mutation SingleUpload($file: Upload!) {
singleUpload(file: $file) {
id
path
filename
mimetype
}
}

Create an instance of Upload using one of the factory methods:

// If you're on Android/JVM, you can turn a File into an upload
val upload = File.toUpload("application/json")
// On multiplatform, you can use `DefaultUpload`
val upload = DefaultUpload.Builder()
.fileName("filename.txt")
.content { sink ->
okioSource.use { sink.writeAll(it) }
}
.build()

And execute your mutation:

val response = apolloClient.mutation(SingleUploadMutation(file = upload)).execute()
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