Sql bug fixed

src/app/services/offline-manager.service.ts

@@ -0,0 +1,94 @@
+import { Injectable } from '@angular/core';
+import { Storage } from '@ionic/storage';
+import { Observable, from, of, forkJoin } from 'rxjs';
+import { switchMap, finalize } from 'rxjs/operators';
+import { HttpClient } from '@angular/common/http';
+import { ToastController } from '@ionic/angular';
+const STORAGE_REQ_KEY = 'storedreq';
+ 
+interface StoredRequest {
+  url: string,
+  type: string,
+  data: any,
+  time: number,
+  id: string
+}
+ 
+@Injectable({
+  providedIn: 'root'
+})
+export class OfflineManagerService {
+ 
+  constructor(
+    private storage: Storage, 
+    private http: HttpClient, 
+    private toastController: ToastController) { }
+ 
+  checkForEvents(): Observable<any> {
+    return from(this.storage.get(STORAGE_REQ_KEY)).pipe(
+      switchMap(storedOperations => {
+        let storedObj = JSON.parse(storedOperations);
+        if (storedObj && storedObj.length > 0) {
+          return this.sendRequests(storedObj).pipe(
+            finalize(() => {
+              let toast = this.toastController.create({
+                message: `Local data succesfully synced to API!`,
+                duration: 3000,
+                position: 'bottom'
+              });
+              toast.then(toast => toast.present());
+ 
+              this.storage.remove(STORAGE_REQ_KEY);
+            })
+          );
+        } else {
+          console.log('no local events to sync');
+          return of(false);
+        }
+      })
+    )
+  }
+ 
+  storeRequest(url, type, data) {
+    let toast = this.toastController.create({
+      message: `Your data is stored locally because you seem to be offline.`,
+      duration: 3000,
+      position: 'bottom'
+    });
+    toast.then(toast => toast.present());
+ 
+    let action: StoredRequest = {
+      url: url,
+      type: type,
+      data: data,
+      time: new Date().getTime(),
+      id: Math.random().toString(36).replace(/[^a-z]+/g, '').substr(0, 5)
+    };
+ 
+    return this.storage.get(STORAGE_REQ_KEY).then(storedOperations => {
+      let storedObj = JSON.parse(storedOperations);
+ 
+      if (storedObj) {
+        storedObj.push(action);
+      } else {
+        storedObj = [action];
+      }
+      // Save old & new local transactions back to Storage
+      return this.storage.set(STORAGE_REQ_KEY, JSON.stringify(storedObj));
+    });
+  }
+ 
+  sendRequests(operations: StoredRequest[]) {
+    let obs = [];
+ 
+    for (let op of operations) {
+      console.log('Make one request: ', op);
+      let oneObs = this.http.request(op.type, op.url, op.data);
+      
+      obs.push(oneObs);
+    }
+ 
+    // Send out all local events and return once they are finished
+    return forkJoin(obs);
+  }
+}