Problem Description

When a query contains a few variables with custom types, the API.swift generation may end up with a the following error:

ambiguous use of “map”

It looks like the one-liner init passing a dictionary as snapshot is the problem, I suspect it being too complex to evaluate with all the flatMap required.

Example

Assuming the following query:

query ProjectOverview(
    $projectId: ID!,
    $endDate: NaiveDateTime!
    $previousDate: NaiveDateTime!
    ) {
        project(id: $projectId) {
        id
        key
        name
        clientName

        lastProjectSourceScores(endDate: $endDate) {
            value
            source {
                id
                name
            }
        }

        previousScores:lastProjectSourceScores(endDate: $previousDate) {
            value
            source {
                id
                name
            }
        }

        events {
            value
            metadata {
                name
                content
            }
            sentAt
            source {
                name
            }
        }
    }
}

The following init will be generated, and will raise an ambiguous use of ‘map’ error:

public init(id: GraphQLID, key: String, name: String, clientName: String, lastProjectSourceScores: [LastProjectSourceScore?]? = nil, previousScores: [PreviousScore?]? = nil, events: [Event?]? = nil) {
        self.init(snapshot: ["__typename": "Project", "id": id, "key": key, "name": name, "clientName": clientName, "lastProjectSourceScores": lastProjectSourceScores.flatMap { $0.map { $0.flatMap { $0.snapshot } } }, "previousScores": previousScores.flatMap { $0.map { $0.flatMap { $0.snapshot } } }, "events": events.flatMap { $0.map { $0.flatMap { $0.snapshot } } }])
}

Workaround fix

It is possible to temporary fix the generated by extracting all the flatMap into variables, and passing those variables into the dictionary instead. That’s why I suspect the generated code being too complex.

public init(id: GraphQLID, key: String, name: String, clientName: String, lastProjectSourceScores: [LastProjectSourceScore?]? = nil, previousScores: [PreviousScore?]? = nil, events: [Event?]? = nil) {
        let lastProjectSourceScoresMap = lastProjectSourceScores.flatMap { $0.map { $0.flatMap { $0.snapshot } } }
        let previousScoresMap = previousScores.flatMap { $0.map { $0.flatMap { $0.snapshot } } }
        let eventsMap = events.flatMap { $0.map { $0.flatMap { $0.snapshot } } }
        self.init(snapshot: ["__typename": "Project", "id": id, "key": key, "name": name, "clientName": clientName, "lastProjectSourceScores": lastProjectSourceScoresMap, "previousScores": previousScoresMap, "events": eventsMap])
}

This solution is not viable, as the next build command with the Apollo Run Script will overwrite it again. The right way to do it would be to fix the code generation snippet.