Pagination utilities

Sources/SDK/Requests/MoltinRequest.swift

@@ -244,6 +244,33 @@ public class MoltinRequest {
         return self
     }
 
+    /**
+     Construct a pagination request, and return an instance of type `T`, which must be `Codable`
+
+     - Author:
+     Craig Tweedy
+
+     - parameters:
+     - withURL: The URL constructed from a path to call
+     - completionHandler: The handler to be called on success or failure
+     - returns:
+     A instance of `MoltinRequest` which encapsulates the request.
+     */
+    @discardableResult internal func paginationRequest<T: Codable>(withURL url: URL, completionHandler: @escaping CollectionRequestHandler<T>) -> Self {
+
+        let urlRequest = URLRequest(url: url)
+
+        self.send(withURLRequest: urlRequest) { (data, response, error) in
+            if error != nil {
+                completionHandler(.failure(error: MoltinError.responseError(underlyingError: error)))
+                return
+            }
+            self.parser.collectionHandler(withData: data, withResponse: response, completionHandler: completionHandler)
+        }
+
+        return self
+    }
+
     private func send(withURLRequest urlRequest: URLRequest, completionHandler: @escaping (Data?, URLResponse?, Error?) -> Void) {
         self.auth.authenticate { [weak self] (result) in
             switch result {

Sources/SDK/Utils/Error.swift

@@ -25,6 +25,8 @@ public enum MoltinError: Error {
     case unacceptableRequest
     /// Thrown if no data was returned from the API
     case noData
+    /// Thrown if no next or previous page for this call was available
+    case noPageAvailable
 }
 
 extension MoltinError: LocalizedError {
@@ -46,6 +48,8 @@ extension MoltinError: LocalizedError {
             return "Could not compose request"
         case .couldNotSetData:
             return "Could not serialize data"
+        case .noPageAvailable:
+            return "No page available"
         }
     }
 }

Sources/SDK/Utils/Pagination.swift

@@ -18,6 +18,98 @@ open class PaginatedResponse<T: Codable>: Codable {
     public var links: [String: String?]?
     /// The meta information for this response
     public var meta: PaginationMeta?
+
+    /**
+     Get the next page for this response
+
+     - Author:
+     Craig Tweedy
+
+     - parameters:
+         - withConfig: The moltin config to use
+         - withCompletion: The handler to be called on success or failure
+     - returns:
+        A instance of `MoltinRequest` which encapsulates the request.
+     */
+    @discardableResult public func next(withConfig config: MoltinConfig, withCompletion completionHandler: @escaping (Result<PaginatedResponse<T>>) -> Void) -> MoltinRequest? {
+        guard let page = self.links?["next"] as? String,
+            let url = URL(string: page) else {
+            completionHandler(.failure(error: MoltinError.noPageAvailable))
+            return nil
+        }
+
+        let request = MoltinRequest(withConfiguration: config)
+        return request.paginationRequest(withURL: url, completionHandler: completionHandler)
+    }
+
+    /**
+     Get the previous page for this response
+
+     - Author:
+        Craig Tweedy
+
+     - parameters:
+        - withConfig: The moltin config to use
+        - withCompletion: The handler to be called on success or failure
+     - returns:
+        A instance of `MoltinRequest` which encapsulates the request.
+     */
+    @discardableResult public func previous(withConfig config: MoltinConfig, withCompletion completionHandler: @escaping (Result<PaginatedResponse<T>>) -> Void) -> MoltinRequest? {
+        guard let page = self.links?["prev"] as? String,
+            let url = URL(string: page) else {
+                completionHandler(.failure(error: MoltinError.noPageAvailable))
+                return nil
+        }
+
+        let request = MoltinRequest(withConfiguration: config)
+        return request.paginationRequest(withURL: url, completionHandler: completionHandler)
+    }
+
+    /**
+     Get the first page for this response
+
+     - Author:
+     Craig Tweedy
+
+     - parameters:
+        - withConfig: The moltin config to use
+        - withCompletion: The handler to be called on success or failure
+     - returns:
+        A instance of `MoltinRequest` which encapsulates the request.
+     */
+    @discardableResult public func first(withConfig config: MoltinConfig, withCompletion completionHandler: @escaping (Result<PaginatedResponse<T>>) -> Void) -> MoltinRequest? {
+        guard let page = self.links?["first"] as? String,
+            let url = URL(string: page) else {
+                completionHandler(.failure(error: MoltinError.noPageAvailable))
+                return nil
+        }
+
+        let request = MoltinRequest(withConfiguration: config)
+        return request.paginationRequest(withURL: url, completionHandler: completionHandler)
+    }
+
+    /**
+     Get the last page for this response
+
+     - Author:
+     Craig Tweedy
+
+     - parameters:
+        - withConfig: The moltin config to use
+        - withCompletion: The handler to be called on success or failure
+     - returns:
+        A instance of `MoltinRequest` which encapsulates the request.
+     */
+    @discardableResult public func last(withConfig config: MoltinConfig, withCompletion completionHandler: @escaping (Result<PaginatedResponse<T>>) -> Void) -> MoltinRequest? {
+        guard let page = self.links?["last"] as? String,
+            let url = URL(string: page) else {
+                completionHandler(.failure(error: MoltinError.noPageAvailable))
+                return nil
+        }
+
+        let request = MoltinRequest(withConfiguration: config)
+        return request.paginationRequest(withURL: url, completionHandler: completionHandler)
+    }
 }
 
 /// `PaginationMeta` gives information about the pagination details to the user, such as result information and page information

moltin.playground/Contents.swift

@@ -8,15 +8,6 @@ PlaygroundPage.current.needsIndefiniteExecution = true
 
 let moltin = Moltin(withClientID: "j6hSilXRQfxKohTndUuVrErLcSJWP15P347L6Im0M4")
 
-moltin.product.all { (result: Result<PaginatedResponse<[Product]>>) in
-    switch result {
-    case .success(let products):
-        print(products)
-    case .failure(let error):
-        print(error)
-    }
-}
-
 moltin.product.all { (result) in
     guard case .success(let products) = result else {
         // something went wrong
@@ -25,4 +16,15 @@ moltin.product.all { (result) in
     }
 
     print(products)
+
+    products.next(withConfig: moltin.config) { (paginatedResult) in
+        guard case .success(let nextPage) = paginatedResult else {
+            // something went wrong
+            if case .failure(let error) = paginatedResult { print(error) }
+            return
+        }
+
+        print(nextPage)
+
+    }
 }

moltin.xcodeproj/xcuserdata/craigtweedy.xcuserdatad/xcschemes/xcschememanagement.plist

@@ -4,68 +4,40 @@
 <dict>
 	<key>SchemeUserState</key>
 	<dict>
-		<key>moltin WatchKit Example.xcscheme</key>
-		<dict>
-			<key>orderHint</key>
-			<integer>5</integer>
-		</dict>
 		<key>moltin WatchKit Example.xcscheme_^#shared#^_</key>
-		<dict>
-			<key>orderHint</key>
-			<integer>5</integer>
-		</dict>
-		<key>moltin iOS Example.xcscheme</key>
 		<dict>
 			<key>orderHint</key>
 			<integer>4</integer>
 		</dict>
 		<key>moltin iOS Example.xcscheme_^#shared#^_</key>
 		<dict>
 			<key>orderHint</key>
-			<integer>4</integer>
+			<integer>1</integer>
 		</dict>
 		<key>moltin iOS Tests.xcscheme</key>
 		<dict>
 			<key>orderHint</key>
-			<integer>3</integer>
+			<integer>2</integer>
 		</dict>
 		<key>moltin iOS.xcscheme_^#shared#^_</key>
 		<dict>
 			<key>orderHint</key>
-			<integer>1</integer>
-		</dict>
-		<key>moltin tvOS Example.xcscheme</key>
-		<dict>
-			<key>orderHint</key>
-			<integer>6</integer>
+			<integer>0</integer>
 		</dict>
 		<key>moltin tvOS Example.xcscheme_^#shared#^_</key>
 		<dict>
 			<key>orderHint</key>
 			<integer>6</integer>
 		</dict>
-		<key>moltin tvOS Tests.xcscheme</key>
-		<dict>
-			<key>orderHint</key>
-			<integer>5</integer>
-		</dict>
 		<key>moltin tvOS.xcscheme_^#shared#^_</key>
 		<dict>
 			<key>orderHint</key>
-			<integer>2</integer>
+			<integer>3</integer>
 		</dict>
 		<key>moltin watchOS.xcscheme_^#shared#^_</key>
 		<dict>
 			<key>orderHint</key>
-			<integer>0</integer>
-		</dict>
-	</dict>
-	<key>SuppressBuildableAutocreation</key>
-	<dict>
-		<key>C392EA11203DB7EB006CD1D0</key>
-		<dict>
-			<key>primary</key>
-			<true/>
+			<integer>5</integer>
 		</dict>
 	</dict>
 </dict>