Allow Statements to take advantage of QueryOptions (#236)

* Allow Statements to take advantage of QueryOptions, primarily creating a Cursor on statements
* Make sure Cursors and Statements are cleaned up correctly in their destructors
* Clean up error handling

Signed-off-by: Mark Irish <mirish@ibm.com>

Author: markirish

.gitignore

@@ -2,7 +2,7 @@ a.out
 node_modules
 deps
 .idea
-core
+core*
 *.env
 .vscode
 build*

lib/Connection.js

@@ -2,6 +2,9 @@ const { Statement } = require('./Statement');
 const { Cursor }    = require('./Cursor');
 
 class Connection {
+
+  CONNECTION_CLOSED_ERROR = 'Connection has already been closed!';
+
   /**
    * An open connection to the database made through an ODBC driver
    * @constructor
@@ -13,10 +16,18 @@ class Connection {
   }
 
   get connected() {
+    if (!this.odbcConnection)
+    {
+      return false;
+    }
     return this.odbcConnection.connected;
   }
 
   get autocommit() {
+    if (!this.odbcConnection)
+    {
+      throw new Error(CONNECTION_CLOSED_ERROR);
+    }
     return this.odbcConnection.autocommit;
   }
 
@@ -85,6 +96,10 @@ class Connection {
     }
 
     if (typeof callback !== 'function') {
+      if (!this.odbcConnection)
+      {
+        throw new Error(Connection.CONNECTION_CLOSED_ERROR);
+      }
       return new Promise((resolve, reject) => {
         this.odbcConnection.query(sql, parameters, options, (error, result) => {
           if (error) {
@@ -109,28 +124,32 @@ class Connection {
       });
     }
 
-    process.nextTick(() => {
-      if (options &&
-        (
-          options.hasOwnProperty('fetchSize') ||
-          options.hasOwnProperty('cursor')
+    if (!this.odbcConnection) {
+      callback(new Error(Connection.CONNECTION_CLOSED_ERROR));
+    } else {
+      process.nextTick(() => {
+        if (options &&
+          (
+            options.hasOwnProperty('fetchSize') ||
+            options.hasOwnProperty('cursor')
+          )
         )
-      )
-      {
-        this.odbcConnection.query(sql, parameters, options, (error, result) => {
-          if (error) {
-            return callback(error);
-          }
+        {
+          this.odbcConnection.query(sql, parameters, options, (error, result) => {
+            if (error) {
+              return callback(error);
+            }
 
-          const cursor = new Cursor(result);
-          return callback(error, cursor);
-        });
-      }
-      else
-      {
-        this.odbcConnection.query(sql, parameters, options, callback);
-      }
-    })
+            const cursor = new Cursor(result);
+            return callback(error, cursor);
+          });
+        }
+        else
+        {
+          this.odbcConnection.query(sql, parameters, options, callback);
+        }
+      });
+    }
   }
 
   /**
@@ -170,6 +189,10 @@ class Connection {
 
     // promise...
     if (callback === undefined) {
+      if (!this.odbcConnection)
+      {
+        throw new Error(Connection.CONNECTION_CLOSED_ERROR);
+      }
       return new Promise((resolve, reject) => {
         this.odbcConnection.callProcedure(catalog, schema, name, parameters, (error, result) => {
           if (error) {
@@ -182,7 +205,11 @@ class Connection {
     }
 
     // ...or callback
-    return this.odbcConnection.callProcedure(catalog, schema, name, parameters, callback);
+    if (!this.odbcConnection) {
+      callback(new Error(Connection.CONNECTION_CLOSED_ERROR));
+    } else {
+      this.odbcConnection.callProcedure(catalog, schema, name, parameters, callback);
+    }
   }
 
   // TODO: Write the documentation
@@ -198,6 +225,10 @@ class Connection {
 
     // promise...
     if (callback === undefined) {
+      if (!this.odbcConnection)
+      {
+        throw new Error(Connection.CONNECTION_CLOSED_ERROR);
+      }
       return new Promise((resolve, reject) => {
         this.odbcConnection.createStatement((error, odbcStatement) => {
           if (error) {
@@ -212,12 +243,16 @@ class Connection {
 
 
     // ...or callback
-    return this.odbcConnection.createStatement((error, odbcStatement) => {
-      if (error) { return callback(error, null); }
-
-      const statement = new Statement(odbcStatement);
-      return callback(null, statement);
-    });
+    if (!this.odbcConnection) {
+      callback(new Error(Connection.CONNECTION_CLOSED_ERROR));
+    } else {
+      this.odbcConnection.createStatement((error, odbcStatement) => {
+        if (error) { return callback(error, null); }
+
+        const statement = new Statement(odbcStatement);
+        callback(null, statement);
+      });
+    }
   }
 
   /** TODO:
@@ -234,25 +269,40 @@ class Connection {
 
     // promise...
     if (callback === undefined) {
+      if (!this.odbcConnection)
+      {
+        throw new Error(Connection.CONNECTION_CLOSED_ERROR);
+      }
       return new Promise((resolve, reject) => {
         this.odbcConnection.close((error) => {
           if (error) {
             reject(error);
           } else {
+            this.odbcConnection = null;
             resolve();
           }
         });
       });
     }
 
     // ...or callback
-    return this.odbcConnection.close(callback);
+    return this.odbcConnection.close((error) => {
+      if (!error)
+      {
+        this.odbcConnection = null;
+      }
+      return callback(error);
+    });
   }
 
   // TODO: Documentation
   columns(catalog, schema, table, type, callback = undefined) {
     // promise...
     if (callback === undefined) {
+      if (!this.odbcConnection)
+      {
+        throw new Error(Connection.CONNECTION_CLOSED_ERROR);
+      }
       return new Promise((resolve, reject) => {
         this.odbcConnection.columns(catalog, schema, table, type, (error, result) => {
           if (error) {
@@ -265,14 +315,21 @@ class Connection {
     }
 
     // ...or callback
-    this.odbcConnection.columns(catalog, schema, table, type, callback);
-    return undefined;
+    if (!this.odbcConnection) {
+      callback(new Error(Connection.CONNECTION_CLOSED_ERROR));
+    } else {
+      this.odbcConnection.columns(catalog, schema, table, type, callback);
+    }
   }
 
   // TODO: Documentation
   tables(catalog, schema, table, type, callback = undefined) {
     // promise...
     if (callback === undefined) {
+      if (!this.odbcConnection)
+      {
+        throw new Error(Connection.CONNECTION_CLOSED_ERROR);
+      }
       return new Promise((resolve, reject) => {
         this.odbcConnection.tables(catalog, schema, table, type, (error, result) => {
           if (error) {
@@ -285,14 +342,21 @@ class Connection {
     }
 
     // ...or callback
-    this.odbcConnection.tables(catalog, schema, table, type, callback);
-    return undefined;
+    if (!this.odbcConnection) {
+      callback(new Error(Connection.CONNECTION_CLOSED_ERROR));
+    } else {
+      this.odbcConnection.tables(catalog, schema, table, type, callback);
+    }
   }
 
   // TODO: Documentation
   setIsolationLevel(isolationLevel, callback = undefined) {
     // promise...
     if (callback === undefined) {
+      if (!this.odbcConnection)
+      {
+        throw new Error(Connection.CONNECTION_CLOSED_ERROR);
+      }
       return new Promise((resolve, reject) => {
         this.odbcConnection.setIsolationLevel(isolationLevel, (error) => {
           if (error) {
@@ -305,7 +369,11 @@ class Connection {
     }
 
     // ...or callback
-    return this.odbcConnection.setIsolationLevel(isolationLevel, callback);
+    if (!this.odbcConnection) {
+      callback(new Error(Connection.CONNECTION_CLOSED_ERROR));
+    } else {
+      this.odbcConnection.setIsolationLevel(isolationLevel, callback);
+    }
   }
 
   /**
@@ -316,6 +384,10 @@ class Connection {
   beginTransaction(callback = undefined) {
     // promise...
     if (callback === undefined) {
+      if (!this.odbcConnection)
+      {
+        throw new Error(Connection.CONNECTION_CLOSED_ERROR);
+      }
       return new Promise((resolve, reject) => {
         this.odbcConnection.beginTransaction((error, result) => {
           if (error) {
@@ -328,7 +400,11 @@ class Connection {
     }
 
     // ...or callback
-    return this.odbcConnection.beginTransaction(callback);
+    if (!this.odbcConnection) {
+      callback(new Error(Connection.CONNECTION_CLOSED_ERROR));
+    } else {
+      this.odbcConnection.beginTransaction(callback);
+    }
   }
 
   /**
@@ -337,6 +413,10 @@ class Connection {
    */
   commit(callback = undefined) {
     if (callback === undefined) {
+      if (!this.odbcConnection)
+      {
+        throw new Error(Connection.CONNECTION_CLOSED_ERROR);
+      }
       return new Promise((resolve, reject) => {
         this.odbcConnection.commit((error) => {
           if (error) {
@@ -348,7 +428,11 @@ class Connection {
       });
     }
 
-    return this.odbcConnection.commit(callback);
+    if (!this.odbcConnection) {
+      callback(new Error(Connection.CONNECTION_CLOSED_ERROR));
+    } else {
+      this.odbcConnection.commit(callback);
+    }
   }
 
   /**
@@ -357,6 +441,10 @@ class Connection {
    */
   rollback(callback = undefined) {
     if (callback === undefined) {
+      if (!this.odbcConnection)
+      {
+        throw new Error(Connection.CONNECTION_CLOSED_ERROR);
+      }
       return new Promise((resolve, reject) => {
         this.odbcConnection.rollback((error) => {
           if (error) {
@@ -368,7 +456,11 @@ class Connection {
       });
     }
 
-    return this.odbcConnection.rollback(callback);
+    if (!this.odbcConnection) {
+      callback(new Error(Connection.CONNECTION_CLOSED_ERROR));
+    } else {
+      this.odbcConnection.rollback(callback);
+    }
   }
 }