Merge pull request #78 from vapor/transactions

Added Transaction to connection

Author: BrettRToomey

Sources/MySQL/Connection.swift

@@ -46,7 +46,31 @@ public final class Connection {
 
         mysql_set_character_set(cConnection, encoding)
     }
-
+    
+    public func transaction(_ closure: () throws -> Void) throws {
+        // required by transactions, but I don't want to open the old
+        // MySQL query API to the public as it would be a burden to maintain.
+        func oldQuery(_ query: String) throws {
+            try lock.locked {
+                guard mysql_query(cConnection, query) == 0 else {
+                    throw Error.execute(error)
+                }
+            }
+        }
+        
+        try oldQuery("START TRANSACTION")
+        
+        do {
+            try closure()
+        } catch {
+            // rollback changes and then rethrow the error
+            try oldQuery("ROLLBACK")
+            throw error
+        }
+        
+        try oldQuery("COMMIT")
+    }
+    
     @discardableResult
     public func execute(_ query: String, _ values: [NodeRepresentable] = []) throws -> [[String: Node]] {
         var returnable: [[String: Node]] = []

Tests/LinuxMain.swift

@@ -4,7 +4,8 @@ import XCTest
 @testable import MySQLTests
 
 XCTMain([
-    testCase(MySQLTests.allTests)
+    testCase(DateTests.allTests),
+    testCase(MySQLTests.allTests),
 ])
 
-#endif
+#endif

Tests/MySQLTests/MySQLTests.swift

@@ -11,6 +11,8 @@ class MySQLTests: XCTestCase {
         ("testTimestamps", testTimestamps),
         ("testSpam", testSpam),
         ("testError", testError),
+        ("testTransaction", testTransaction),
+        ("testTransactionFailed", testTransactionFailed),
     ]
 
     var mysql: MySQL.Database!
@@ -201,4 +203,59 @@ class MySQLTests: XCTestCase {
             XCTFail("Wrong error: \(error)")
         }
     }
+    
+    func testTransaction() {
+        do {
+            let c = try mysql.makeConnection()
+            try c.execute("DROP TABLE IF EXISTS transaction")
+            try c.execute("CREATE TABLE transaction (name VARCHAR(64))")
+            try c.execute("INSERT INTO transaction VALUES (?)", [
+                "james"
+            ])
+            
+            try c.transaction {
+                try c.execute("UPDATE transaction SET name = 'James' where name = 'james'")
+            }
+            
+            if let james = try c.execute("SELECT * FROM transaction").first {
+                XCTAssertEqual(james["name"]?.string, "James")
+            } else {
+                XCTFail("There should be one entry.")
+            }
+        } catch {
+            XCTFail("Testing transaction failed: \(error)")
+        }
+    }
+    
+    func testTransactionFailed() {
+        do {
+            let c = try mysql.makeConnection()
+            try c.execute("DROP TABLE IF EXISTS transaction")
+            try c.execute("CREATE TABLE transaction (name VARCHAR(64))")
+            try c.execute("INSERT INTO transaction VALUES (?)", [
+                "tommy"
+            ])
+            
+            do {
+                try c.transaction {
+                    // will succeed, but will be rolled back
+                    try c.execute("UPDATE transaction SET name = 'Timmy'")
+                    
+                    // malformed query, will throw
+                    try c.execute("💉")
+                }
+                
+                XCTFail("Transaction should have rethrown error.")
+                
+            } catch {
+                if let tommy = try c.execute("SELECT * FROM transaction").first {
+                    XCTAssertEqual(tommy["name"]?.string, "tommy", "Should have ROLLBACK")
+                } else {
+                    XCTFail("There should be one entry.")
+                }
+            }
+        } catch {
+            XCTFail("Testing transaction failed: \(error)")
+        }
+    }
 }