onCall

Specifies the block handler for every incoming ApplicationCall.

This block is invoked for every incoming call even if the call is already handled by other handler. There you can handle the call in a way you want: add headers, change the response status, etc. You can also access the external state to calculate stats.

This example demonstrates how to create a plugin that appends a custom header to each response:

val CustomHeaderPlugin = createApplicationPlugin(name = "CustomHeaderPlugin") {
    onCall { call ->
        call.response.headers.append("X-Custom-Header", "Hello, world!")
    }
}

See also

Parameters