code fix

crawler/helper/database.js

@@ -0,0 +1,31 @@
+module.exports = {
+    insertTodayDomains : function (db, domains){
+        return new Promise((resolve,reject)=>{
+            db.collection('today').insert(domains, ()=>{
+                resolve();
+            });
+        });
+    },
+
+    getYesterdayDomains : function (db){
+        return getArrayFromDatabase(db, 'yesterday');
+    },
+
+    getExpiredDomains : function (db){
+        return getArrayFromDatabase(db, 'expired_list');
+    }
+
+
+};
+
+const getArrayFromDatabase = function(db, collection){
+    return new Promise((resolve,reject)=>{
+        db.collection(collection).find({}).toArray((err,result)=>{
+            if (err){
+                reject('Error reading collection');
+            }else{
+                resolve(result);
+            }
+        });
+    });
+}