Merge branch 'fix_database_error_reporting' into 'development'

Fix error handling in the database query module

Changes in this merge request
* Add proper error handling in libs/db/query_exec. Uses a catch function after each then to proper capture database errors and report them to the user.
* Add logging the error stack when a database query error occurs.
* Change error message reported in the response when a database query occurs, because the user making the request does not need to know about an internal database error.

See merge request !28

src/libs/app.js

@@ -37,16 +37,17 @@ app.use((req, res, next) => {
     req.sql = squel.select();
     next();
 });
+// Mounts all API routes under /api/v1
 app.use('/api/v1', api);
 
 // Catch 404 and forward to error handler
 app.use((req, res, next) => {
     res.status(404);
     log.error('%s %d %s', req.method, res.statusCode, req.url);
-    res.json({ error: 'Not found' }).end();
+    res.json({ error: 'Error 404: Page not found' }).end();
 });
 
-// Error handlers
+// Express' default error handler
 app.use((err, req, res, next) => {
     res.status(err.status || 500);
     log.error('%s %d %s', req.method, res.statusCode, err.message);

src/libs/db/query_exec.js

@@ -19,26 +19,23 @@ function execSqlQuery(sqlQuery, sqlQueryParams = []) {
     log.debug(`Executing SQL query '${sqlQuery}' with params '${sqlQueryParams}'`);
     return new Promise((resolve, reject) => {
         // Prepare statement
-        conn.prepare(sqlQuery, true).then(
-            (dbQuery) => {
-                // Execute query
-                dbQuery.exec(sqlQueryParams).then(
-                    // Success
-                    (dbResult) => {
-                        log.debug(`Query result: ${dbResult.data}`);
-                        log.debug(dbResult.data);
-                        resolve(dbResult.data);
-                    },
-                    // Error
-                    (dbError) => {
-                        log.error(`SQL query execution error: ${dbError.message}`);
-                        reject(new Error(dbError.message));
-                    }
-                );
-                // Release resources allocated for prepared statement
-                conn.release();
-            }
-        );
+        conn.prepare(sqlQuery, true).then((dbQuery) => {
+            // Execute query
+            dbQuery.exec(sqlQueryParams).then((dbResult) => {
+                log.debug(`Query result: ${dbResult.data}`);
+                // release resources allocated for the prepared statement
+                dbQuery.release();
+                resolve(dbResult.data);
+            }).catch((queryError) => {
+                log.error(`SQL query execution error: ${queryError.message}`);
+                // release resources allocated for the prepared statement
+                dbQuery.release();
+                reject(new Error(queryError.message));
+            });
+        }).catch((prepError) => {
+            log.error(`SQL prepared statement error: ${prepError.message}`);
+            reject(new Error(prepError.message));
+        });
     });
 }
 

src/libs/middlewares/query.js

@@ -9,10 +9,13 @@ function query(req, res, next) {
     execQuery(sql.text, sql.values).then((result) => {
         log.debug(result);
         req.result = result;
-        if(result.length === 0) next({status: 404, message: 'Not Found'});
+        if (result.length === 0) {
+            next({status: 404, message: 'Not Found'});
+        }
         next();
     }, (error) => {
-        next(error);
+        log.error(error.stack);
+        next(new Error('Request could not be satisfied due to a database error.'));
     });
 }