Kitura/Swift-Kuery#13 Implemented query fetcher and updated the tests

Sources/SwiftKueryPostgreSQL/PostgreSQLConnection.swift

@@ -172,16 +172,16 @@ public class PostgreSQLConnection : Connection {
             onCompletion(.successNoData)
         }
         else if status == PGRES_TUPLES_OK {
-            let (titles, rows) = PostgreSQLConnection.getRows(queryResult: result)
-            onCompletion(.rows(titles: titles, rows: rows))
+            let resultFetcher = PostgreSQLConnection.createReslutFetcher(queryResult: result)
+            onCompletion(.resultSet(ResultSet(resultFetcher)))
         }
         else {
             onCompletion(.error(QueryError.databaseError("Query execution error:\n" + String(validatingUTF8: PQresultErrorMessage(result))! + "For query: " + query)))
         }
         PQclear(result)
     }
 
-    private static func getRows(queryResult: OpaquePointer) -> ([String], [[Any?]]) {
+    private static func createReslutFetcher(queryResult: OpaquePointer) -> PostgreSQLResultFetcher {
         var result = [[Any?]]()
         let rows = PQntuples(queryResult)
         let columns = PQnfields(queryResult)
@@ -205,7 +205,7 @@ public class PostgreSQLConnection : Connection {
             result.append(row)
         }
 
-        return (columnNames, result)
+        return PostgreSQLResultFetcher(titles: columnNames, rows: result)
     }
 
     private static func convert(_ queryResult: OpaquePointer, row: Int32, column: Int32) -> Any {

Sources/SwiftKueryPostgreSQL/PostgreSQLResultFetcher.swift

@@ -0,0 +1,66 @@
+/**
+ Copyright IBM Corporation 2016
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+ */
+
+import SwiftKuery
+
+// MARK: PostgreSQLResultFetcher
+
+/// An implementation of query result fetcher.
+public class PostgreSQLResultFetcher : ResultFetcher {
+
+    private let titles: [String]
+    private let rows: [[Any?]]
+    private var index = -1
+
+    init(titles: [String], rows: [[Any?]]) {
+        self.titles = titles
+        self.rows = rows
+    }
+
+    /// Fetch the next row of the query result. This function is blocking.
+    ///
+    /// - Returns: An array of values of type Any? representing the next row from the query result.
+    public func fetchNext() -> [Any?]? {
+        index += 1
+        if index < rows.count {
+            return (rows[index])
+        }
+        else {
+            return nil
+        }
+    }
+
+    /// Fetch the next row of the query result. This function is non-blocking.
+    ///
+    /// - Parameter callback: A callback to call when the next row of the query result is ready.
+    public func fetchNext(callback: ([Any?]?) ->()) {
+        index += 1
+        if index < rows.count {
+            callback(rows[index])
+        }
+        else {
+            callback(nil)
+        }
+    }
+
+    /// Fetch the titles of the query result. This function is blocking.
+    ///
+    /// - Returns: An array of column titles of type String.
+    public func fetchTitles() -> [String] {
+        return titles
+    }
+
+}

Tests/SwiftKueryPostgreSQLTests/CommonUtils.swift

@@ -51,41 +51,41 @@ func read(fileName: String) -> String {
     }
 }
 
-func executeQuery(query: Query, connection: Connection, callback: @escaping (QueryResult)->()) {
+func executeQuery(query: Query, connection: Connection, callback: @escaping (QueryResult, [[Any?]]?)->()) {
     do {
         try print("=======\(connection.descriptionOf(query: query))=======")
     }
     catch {}
     connection.execute(query: query) { result in
-        printResult(result)
-        callback(result)
+        let rows = printResultAndGetRowsAsArray(result)
+        callback(result, rows)
     }
 }
 
-func executeQueryWithParameters(query: Query, connection: Connection, parameters: Any..., callback: @escaping (QueryResult)->()) {
+func executeQueryWithParameters(query: Query, connection: Connection, parameters: Any..., callback: @escaping (QueryResult, [[Any?]]?)->()) {
     do {
         try print("=======\(connection.descriptionOf(query: query))=======")
     }
     catch {}
     connection.execute(query: query, parameters: parameters) { result in
-        printResult(result)
-        callback(result)
+        let rows = printResultAndGetRowsAsArray(result)
+        callback(result, rows)
     }
 }
 
-func executeRawQueryWithParameters(_ raw: String, connection: Connection, parameters: Any..., callback: @escaping (QueryResult)->()) {
+func executeRawQueryWithParameters(_ raw: String, connection: Connection, parameters: Any..., callback: @escaping (QueryResult, [[Any?]]?)->()) {
     print("=======\(raw)=======")
     connection.execute(raw, parameters: parameters) { result in
-        printResult(result)
-        callback(result)
+        let rows = printResultAndGetRowsAsArray(result)
+        callback(result, rows)
     }
 }
 
-func executeRawQuery(_ raw: String, connection: Connection, callback: @escaping (QueryResult)->()) {
+func executeRawQuery(_ raw: String, connection: Connection, callback: @escaping (QueryResult, [[Any?]]?)->()) {
     print("=======\(raw)=======")
     connection.execute(raw) { result in
-        printResult(result)
-        callback(result)
+        let rows = printResultAndGetRowsAsArray(result)
+        callback(result, rows)
     }
 }
 
@@ -95,21 +95,26 @@ func cleanUp(table: String, connection: Connection, callback: @escaping (QueryRe
     }
 }
 
-func printResult(_ result: QueryResult) {
-    if let (titles, rows) = result.asRows {
+private func printResultAndGetRowsAsArray(_ result: QueryResult) -> [[Any?]]? {
+    var rows: [[Any?]]? = nil
+    if let resultSet = result.asResultSet {
+        let titles = resultSet.titles
         for title in titles {
             print(title.padding(toLength: 11, withPad: " ", startingAt: 0), terminator: "")
         }
         print()
-        for row in rows {
-            for value in row {
-                var valueToPrint = ""
-                if value != nil {
-                    valueToPrint = value as! String
+        rows = rowsAsArray(resultSet)
+        if let rows = rows {
+            for row in rows {
+                for value in row {
+                    var valueToPrint = ""
+                    if value != nil {
+                        valueToPrint = value as! String
+                    }
+                    print(valueToPrint.padding(toLength: 11, withPad: " ", startingAt: 0), terminator: "")
                 }
-                print(valueToPrint.padding(toLength: 11, withPad: " ", startingAt: 0), terminator: "")
+                print()
             }
-            print()
         }
     }
     else if let value = result.asValue  {
@@ -121,6 +126,15 @@ func printResult(_ result: QueryResult) {
     else if let queryError = result.asError {
         print("Error in query: ", queryError)
     }
+    return rows
+}
+
+func getNumberOfRows(_ result: ResultSet) -> Int {
+    return result.rows.map{ $0 as [Any?] }.count
+}
+
+func rowsAsArray(_ result: ResultSet) -> [[Any?]] {
+    return result.rows.map{ $0 as [Any?] }
 }
 
 func createConnection() -> PostgreSQLConnection {
@@ -132,5 +146,6 @@ func createConnection() -> PostgreSQLConnection {
     return PostgreSQLConnection(host: host, port: port, options: [.userName(username), .password(password)])
 }
 
+
 // Dummy class for test framework
 class CommonUtils { }

Tests/SwiftKueryPostgreSQLTests/TestAlias.swift

@@ -51,41 +51,42 @@ class TestAlias: XCTestCase {
 
                 cleanUp(table: t.tableName, connection: connection) { result in
 
-                    executeRawQuery("CREATE TABLE " +  t.tableName + " (a varchar(40), b integer)", connection: connection) { result in
+                    executeRawQuery("CREATE TABLE " +  t.tableName + " (a varchar(40), b integer)", connection: connection) { result, rows in
                         XCTAssertEqual(result.success, true, "CREATE TABLE failed")
                         XCTAssertNil(result.asError, "Error in CREATE TABLE: \(result.asError!)")
 
                         let i1 = Insert(into: t, rows: [["apple", 10], ["apricot", 3], ["banana", 17], ["apple", 17], ["banana", -7], ["banana", 27]])
-                        executeQuery(query: i1, connection: connection) { result in
+                        executeQuery(query: i1, connection: connection) { result, rows in
                             XCTAssertEqual(result.success, true, "INSERT failed")
                             XCTAssertNil(result.asError, "Error in INSERT: \(result.asError!)")
 
                             let s1 = Select(t.a.as("\"fruit name\""), t.b.as("number"), from: t)
-                            executeQuery(query: s1, connection: connection) { result in
+                            executeQuery(query: s1, connection: connection) { result, rows in
                                 XCTAssertEqual(result.success, true, "SELECT failed")
-                                XCTAssertNotNil(result.asRows, "SELECT returned no rows")
-                                let (titles, rows) = result.asRows!
-                                XCTAssertEqual(rows.count, 6, "SELECT returned wrong number of rows: \(rows.count) instead of 6")
-                                XCTAssertEqual(titles[0], "fruit name", "Wrong column name: \(titles[0]) instead of 'fruit name'")
-                                XCTAssertEqual(titles[1], "number", "Wrong column name: \(titles[1]) instead of 'number'")
+                                XCTAssertNotNil(result.asResultSet, "SELECT returned no rows")
+                                XCTAssertNotNil(rows, "SELECT returned no rows")
+                                let resultSet = result.asResultSet!
+                                XCTAssertEqual(rows!.count, 6, "SELECT returned wrong number of rows: \(rows!.count) instead of 6")
+                                XCTAssertEqual(resultSet.titles[1], "number", "Wrong column name: \(resultSet.titles[1]) instead of 'number'")
+                                XCTAssertEqual(resultSet.titles[0], "fruit name", "Wrong column name: \(resultSet.titles[0]) instead of 'fruit name'")
 
                                 let s2 = Select(from: t.as("new"))
-                                executeQuery(query: s2, connection: connection) { result in
+                                executeQuery(query: s2, connection: connection) { result, rows in
                                     XCTAssertEqual(result.success, true, "SELECT failed")
-                                    XCTAssertNotNil(result.asRows, "SELECT returned no rows")
-                                    let (titles, rows) = result.asRows!
-                                    XCTAssertEqual(rows.count, 6, "SELECT returned wrong number of rows: \(rows.count) instead of 6")
-                                    XCTAssertEqual(titles[0], "a", "Wrong column name: \(titles[0]) instead of 'a'")
-                                    XCTAssertEqual(titles[1], "b", "Wrong column name: \(titles[1]) instead of 'b'")
+                                    XCTAssertNotNil(rows, "SELECT returned no rows")
+                                    let resultSet = result.asResultSet!
+                                    XCTAssertEqual(rows!.count, 6, "SELECT returned wrong number of rows: \(rows!.count) instead of 6")
+                                    XCTAssertEqual(resultSet.titles[0], "a", "Wrong column name: \(resultSet.titles[0]) instead of 'a'")
+                                    XCTAssertEqual(resultSet.titles[1], "b", "Wrong column name: \(resultSet.titles[1]) instead of 'b'")
 
                                     let t2 = t.as("\"t 2\"")
                                     let s3 = Select(t2.a, from: t2)
-                                    executeQuery(query: s3, connection: connection) { result in
+                                    executeQuery(query: s3, connection: connection) { result, rows in
                                         XCTAssertEqual(result.success, true, "SELECT failed")
-                                        XCTAssertNotNil(result.asRows, "SELECT returned no rows")
-                                        let (titles, rows) = result.asRows!
-                                        XCTAssertEqual(rows.count, 6, "SELECT returned wrong number of rows: \(rows.count) instead of 6")
-                                        XCTAssertEqual(titles[0], "a", "Wrong column name: \(titles[0]) instead of 'a'")
+                                        XCTAssertNotNil(rows, "SELECT returned no rows")
+                                        let resultSet = result.asResultSet!
+                                        XCTAssertEqual(rows!.count, 6, "SELECT returned wrong number of rows: \(rows!.count) instead of 6")
+                                        XCTAssertEqual(resultSet.titles[0], "a", "Wrong column name: \(resultSet.titles[0]) instead of 'a'")
                                     }
                                 }
                             }