From 585712a25d4013ac54afdc8c75326cbdcd67445e Mon Sep 17 00:00:00 2001
From: GabrielTrettel <gabrielmtrettel@gmail.com>
Date: Thu, 7 Jan 2021 11:51:03 -0300
Subject: [PATCH] undefined checks in database transactions

---
 src/app/database/database-connection.js |  1 +
 src/app/database/database-init.js       |  2 +-
 src/app/hooks/selectFromDB.js           | 16 +++++++++++-----
 3 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/app/database/database-connection.js b/src/app/database/database-connection.js
index f998118..bc9d3f4 100644
--- a/src/app/database/database-connection.js
+++ b/src/app/database/database-connection.js
@@ -3,6 +3,7 @@ import * as SQLite from "expo-sqlite";
 function openDatabase() {
   const db = SQLite.openDatabase("db.testDb");
 
+  // return undefined
   return db;
 }
 
diff --git a/src/app/database/database-init.js b/src/app/database/database-init.js
index f2ad2c2..6234dc3 100644
--- a/src/app/database/database-init.js
+++ b/src/app/database/database-init.js
@@ -28,7 +28,7 @@ function createAllTables(db) {
  *
  */
 function initDatabase(db) {
-  createAllTables(db);
+  (db != undefined && db !== null) && createAllTables(db);
 }
 
 export default initDatabase;
diff --git a/src/app/hooks/selectFromDB.js b/src/app/hooks/selectFromDB.js
index dc7cf4c..e1fd633 100644
--- a/src/app/hooks/selectFromDB.js
+++ b/src/app/hooks/selectFromDB.js
@@ -140,16 +140,22 @@ function parseResult(db_result, parseRow) {
   return warnings;
 }
 
+function isAvailable(dataBase) {
+  return dataBase !== undefined && dataBase !== null;
+}
+
 function genericSelect(queriesToParsersMapper, dispatch, isFocused) {
   useEffect(() => {
     console.log("requesting data");
-    queriesToParsersMapper.forEach(([query, parser]) => {
-      global.userDataBase.transaction((tx) => {
-        tx.executeSql(query, [], (tx, results) => {
-          dispatch({ increment: parseResult(results, parser) });
+    if (isAvailable(global.userDataBase)) {
+      queriesToParsersMapper.forEach(([query, parser]) => {
+        global.userDataBase.transaction((tx) => {
+          tx.executeSql(query, [], (tx, results) => {
+            dispatch({ increment: parseResult(results, parser) });
+          });
         });
       });
-    });
+    }
   }, [isFocused]);
 }