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Merge pull request #8 from futuredapp/feature/network-observers
feat: Add GraphQL network observers matching FTAPIKit pattern
2 parents 4b46c01 + f6c8707 commit 4ae59ac

9 files changed

Lines changed: 687 additions & 52 deletions

‎Package.swift‎

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Original file line numberDiff line numberDiff line change
@@ -29,6 +29,12 @@ let package = Package(
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dependencies: [
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.product(name: "Apollo", package: "apollo-ios"),
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]
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),
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.testTarget(
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name: "GraphQLAPIKitTests",
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dependencies: [
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"GraphQLAPIKit"
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]
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)
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]
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)

‎Sources/GraphQLAPIKit/GraphQLAPIAdapter.swift‎

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@@ -18,7 +18,7 @@ public protocol GraphQLAPIAdapterProtocol: AnyObject {
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queue: DispatchQueue,
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resultHandler: @escaping (Result<Query.Data, GraphQLAPIAdapterError>) -> Void
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) -> Cancellable
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/// Performs a mutation by sending it to the server.
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///
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/// - Parameters:
@@ -38,14 +38,42 @@ public protocol GraphQLAPIAdapterProtocol: AnyObject {
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public final class GraphQLAPIAdapter: GraphQLAPIAdapterProtocol {
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private let apollo: ApolloClientProtocol
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public init<each Observer: GraphQLNetworkObserver>(
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url: URL,
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urlSessionConfiguration: URLSessionConfiguration = .default,
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defaultHeaders: [String: String] = [:],
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networkObservers: repeat each Observer
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) {
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var observers: [any GraphQLNetworkObserver] = []
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repeat observers.append(each networkObservers)
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let provider = NetworkInterceptorProvider(
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client: URLSessionClient(sessionConfiguration: urlSessionConfiguration),
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defaultHeaders: defaultHeaders,
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networkObservers: observers
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)
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let networkTransport = RequestChainNetworkTransport(
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interceptorProvider: provider,
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endpointURL: url
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)
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self.apollo = ApolloClient(
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networkTransport: networkTransport,
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store: ApolloStore()
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)
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}
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public init(
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url: URL,
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urlSessionConfiguration: URLSessionConfiguration = .default,
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defaultHeaders: [String: String] = [:]
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defaultHeaders: [String: String] = [:],
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networkObservers: [any GraphQLNetworkObserver]
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) {
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let provider = NetworkInterceptorProvider(
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client: URLSessionClient(sessionConfiguration: urlSessionConfiguration),
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defaultHeaders: defaultHeaders
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defaultHeaders: defaultHeaders,
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networkObservers: networkObservers
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)
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let networkTransport = RequestChainNetworkTransport(
@@ -64,7 +92,7 @@ public final class GraphQLAPIAdapter: GraphQLAPIAdapterProtocol {
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context: RequestHeaders?,
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queue: DispatchQueue,
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resultHandler: @escaping (Result<Query.Data, GraphQLAPIAdapterError>) -> Void
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) -> Cancellable where Query : GraphQLQuery {
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) -> Cancellable where Query: GraphQLQuery {
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apollo.fetch(
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query: query,
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cachePolicy: .fetchIgnoringCacheCompletely,
@@ -92,7 +120,7 @@ public final class GraphQLAPIAdapter: GraphQLAPIAdapterProtocol {
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context: RequestHeaders?,
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queue: DispatchQueue,
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resultHandler: @escaping (Result<Mutation.Data, GraphQLAPIAdapterError>) -> Void
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) -> Cancellable where Mutation : GraphQLMutation {
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) -> Cancellable where Mutation: GraphQLMutation {
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apollo.perform(
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mutation: mutation,
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publishResultToStore: false,
@@ -114,50 +142,3 @@ public final class GraphQLAPIAdapter: GraphQLAPIAdapterProtocol {
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}
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}
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}
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private struct NetworkInterceptorProvider: InterceptorProvider {
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private let client: URLSessionClient
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private let defaultHeaders: [String: String]
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init(client: URLSessionClient, defaultHeaders: [String: String]) {
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self.client = client
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self.defaultHeaders = defaultHeaders
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}
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func interceptors<Operation: GraphQLOperation>(for operation: Operation) -> [ApolloInterceptor] {
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[
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RequestHeaderInterceptor(defaultHeaders: defaultHeaders),
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MaxRetryInterceptor(),
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NetworkFetchInterceptor(client: self.client),
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ResponseCodeInterceptor(),
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MultipartResponseParsingInterceptor(),
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JSONResponseParsingInterceptor()
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]
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}
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}
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private struct RequestHeaderInterceptor: ApolloInterceptor {
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var id: String = UUID().uuidString
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private let defaultHeaders: [String: String]
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init(defaultHeaders: [String: String]) {
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self.defaultHeaders = defaultHeaders
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}
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func interceptAsync<Operation: GraphQLOperation>(
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chain: RequestChain,
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request: HTTPRequest<Operation>,
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response: HTTPResponse<Operation>?,
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completion: @escaping (Result<GraphQLResult<Operation.Data>, Error>) -> Void
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) {
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defaultHeaders.forEach { request.addHeader(name: $0.key, value: $0.value) }
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if let additionalHeaders = request.context as? RequestHeaders {
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additionalHeaders.additionalHeaders.forEach { request.addHeader(name: $0.key, value: $0.value) }
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}
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chain.proceedAsync(request: request, response: response, interceptor: self, completion: completion)
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}
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}
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‎Sources/GraphQLAPIKit/Interceptors/NetworkInterceptorProvider.swift‎

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@@ -0,0 +1,45 @@
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import Apollo
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import ApolloAPI
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import Foundation
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struct NetworkInterceptorProvider: InterceptorProvider {
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private let client: URLSessionClient
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private let defaultHeaders: [String: String]
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private let pairOfObserverInterceptors: [(before: ApolloInterceptor, after: ApolloInterceptor)]
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init(
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client: URLSessionClient,
12+
defaultHeaders: [String: String],
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networkObservers: [any GraphQLNetworkObserver]
14+
) {
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self.client = client
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self.defaultHeaders = defaultHeaders
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// Create interceptor pairs with shared context stores
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self.pairOfObserverInterceptors = networkObservers.map { Self.makePair(of: $0) }
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}
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func interceptors<Operation: GraphQLOperation>(for operation: Operation) -> [ApolloInterceptor] {
22+
// Headers first, then before-observers, then network fetch, then after-observers
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[
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RequestHeaderInterceptor(defaultHeaders: defaultHeaders),
25+
]
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+ pairOfObserverInterceptors.map(\.before) // Before network - captures timing
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+ [
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MaxRetryInterceptor(),
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NetworkFetchInterceptor(client: client)
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]
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+ pairOfObserverInterceptors.map(\.after) // After network - captures response
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+ [
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ResponseCodeInterceptor(),
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MultipartResponseParsingInterceptor(),
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JSONResponseParsingInterceptor()
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]
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}
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static private func makePair<T: GraphQLNetworkObserver>(of observer: T) -> (before: ApolloInterceptor, after: ApolloInterceptor) {
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let contextStore = ObserverContextStore<T.Context>()
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let beforeInterceptor = ObserverInterceptor(observer: observer, contextStore: contextStore)
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let afterInterceptor = ObserverInterceptor(observer: observer, contextStore: contextStore)
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return (before: beforeInterceptor, after: afterInterceptor)
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}
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}

‎Sources/GraphQLAPIKit/Interceptors/ObserverInterceptor.swift‎

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@@ -0,0 +1,61 @@
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import Apollo
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import ApolloAPI
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import Foundation
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/// Interceptor that observes network requests. Place TWO instances in chain:
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/// - One BEFORE NetworkFetchInterceptor (captures request timing)
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/// - One AFTER NetworkFetchInterceptor (captures response)
8+
/// Both instances share state via the contextStore actor.
9+
struct ObserverInterceptor<Observer: GraphQLNetworkObserver>: ApolloInterceptor {
10+
let id = UUID().uuidString
11+
12+
private let observer: Observer
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private let contextStore: ObserverContextStore<Observer.Context>
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15+
init(observer: Observer, contextStore: ObserverContextStore<Observer.Context>) {
16+
self.observer = observer
17+
self.contextStore = contextStore
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}
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20+
func interceptAsync<Operation: GraphQLOperation>(
21+
chain: RequestChain,
22+
request: HTTPRequest<Operation>,
23+
response: HTTPResponse<Operation>?,
24+
completion: @escaping (Result<GraphQLResult<Operation.Data>, Error>) -> Void
25+
) {
26+
guard let urlRequest = try? request.toURLRequest() else {
27+
chain.proceedAsync(request: request, response: response, interceptor: self, completion: completion)
28+
return
29+
}
30+
31+
let requestId = ObjectIdentifier(request).debugDescription
32+
33+
if response == nil {
34+
// BEFORE network fetch - call willSendRequest and store context synchronously
35+
let context = observer.willSendRequest(urlRequest)
36+
contextStore.store(context, for: requestId)
37+
} else {
38+
// AFTER network fetch - retrieve context and call didReceiveResponse
39+
if let context = contextStore.retrieve(for: requestId) {
40+
observer.didReceiveResponse(
41+
for: urlRequest,
42+
response: response?.httpResponse,
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data: response?.rawData,
44+
context: context
45+
)
46+
}
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}
48+
49+
// Wrap completion to handle errors
50+
let wrappedCompletion: (Result<GraphQLResult<Operation.Data>, Error>) -> Void = { result in
51+
if case .failure(let error) = result {
52+
if let context = contextStore.retrieve(for: requestId) {
53+
observer.didFail(request: urlRequest, error: error, context: context)
54+
}
55+
}
56+
completion(result)
57+
}
58+
59+
chain.proceedAsync(request: request, response: response, interceptor: self, completion: wrappedCompletion)
60+
}
61+
}

‎Sources/GraphQLAPIKit/Interceptors/RequestHeaderInterceptor.swift‎

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1+
import Apollo
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import ApolloAPI
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import Foundation
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5+
struct RequestHeaderInterceptor: ApolloInterceptor {
6+
let id: String = UUID().uuidString
7+
8+
private let defaultHeaders: [String: String]
9+
10+
init(defaultHeaders: [String: String]) {
11+
self.defaultHeaders = defaultHeaders
12+
}
13+
14+
func interceptAsync<Operation: GraphQLOperation>(
15+
chain: RequestChain,
16+
request: HTTPRequest<Operation>,
17+
response: HTTPResponse<Operation>?,
18+
completion: @escaping (Result<GraphQLResult<Operation.Data>, Error>) -> Void
19+
) {
20+
defaultHeaders.forEach { request.addHeader(name: $0.key, value: $0.value) }
21+
if let additionalHeaders = request.context as? RequestHeaders {
22+
additionalHeaders.additionalHeaders.forEach { request.addHeader(name: $0.key, value: $0.value) }
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}
24+
25+
chain.proceedAsync(request: request, response: response, interceptor: self, completion: completion)
26+
}
27+
}

‎Sources/GraphQLAPIKit/Observers/GraphQLNetworkObserver.swift‎

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1+
import Foundation
2+
3+
/// Protocol for observing GraphQL network request lifecycle events.
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///
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/// Implement this protocol to add logging, analytics, or request tracking to GraphQL operations.
6+
/// Observers are passive - they cannot modify requests or responses, only observe them.
7+
///
8+
/// ## Context Lifecycle
9+
/// The `Context` associated type allows passing correlation data (request ID, start time, etc.)
10+
/// through the request lifecycle:
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/// 1. `willSendRequest` is called before the request starts and returns a `Context` value
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/// 2. `didReceiveResponse` is always called with the raw HTTP response data (useful for debugging)
13+
/// 3. `didFail` is called additionally if the request fails
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/// 4. If the observer is deallocated before the request completes, the context is discarded
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/// and no completion callback is invoked
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///
17+
public protocol GraphQLNetworkObserver: AnyObject, Sendable {
18+
associatedtype Context: Sendable
19+
20+
/// Called immediately before a request is sent.
21+
/// - Parameter request: The URLRequest about to be sent
22+
/// - Returns: Context to be passed to `didReceiveResponse` and optionally `didFail`
23+
func willSendRequest(_ request: URLRequest) -> Context
24+
25+
/// Called when a response is received from the server.
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///
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/// This is always called with the raw response data, even if processing subsequently fails.
28+
/// This allows observers to inspect the actual response for debugging purposes.
29+
/// - Parameters:
30+
/// - request: The original request
31+
/// - response: The URL response (may be nil if network error occurred before response)
32+
/// - data: Response body data, if any
33+
/// - context: Value returned from `willSendRequest`
34+
func didReceiveResponse(for request: URLRequest, response: URLResponse?, data: Data?, context: Context)
35+
36+
/// Called when a request fails with an error.
37+
///
38+
/// Called after `didReceiveResponse` if processing determines the request failed.
39+
/// - Parameters:
40+
/// - request: The original request
41+
/// - error: The error that occurred
42+
/// - context: Value returned from `willSendRequest`
43+
func didFail(request: URLRequest, error: Error, context: Context)
44+
}

‎Sources/GraphQLAPIKit/Observers/ObserverContextStore.swift‎

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1+
import Foundation
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import os
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4+
/// Thread-safe store for observer contexts keyed by request identifier.
5+
/// Enables two interceptor instances to share state across the interceptor chain.
6+
final class ObserverContextStore<Context: Sendable>: Sendable {
7+
private let state = OSAllocatedUnfairLock(initialState: [String: Context]())
8+
9+
func store(_ context: Context, for requestId: String) {
10+
state.withLock { $0[requestId] = context }
11+
}
12+
13+
func retrieve(for requestId: String) -> Context? {
14+
state.withLock { $0.removeValue(forKey: requestId) }
15+
}
16+
}

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