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Uploading files

Apollo Kotlin supports file uploading following the GraphQL multipart request specification.

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

apollo {
  customScalarsMapping = [
    "Upload" : "com.apollographql.apollo3.api.Upload"

In this example, the GraphQL schema defines a custom scalar type named Upload - adapt it to match your own GraphQL schema.

Note: you don't need to register a type adapter for Upload, the runtime will recognize it and use the appropriate adapter.

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

mutation SingleUpload($file: Upload!) {
  singleUpload(file: $file) {

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

val upload = DefaultUpload.Builder()

// or if you're on the JVM
val upload = DefaultUpload.Builder()

And execute your mutation:

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