mdn_approach_only_one_fetch.js

/* This does not work as expected, See stackoverflow answer*/

// Create an instance of a db object for us to store the open database in
let db;

window.onload = function() {
  // Open our database; it is created if it doesn't already exist
  // (see onupgradeneeded below)
  let request = window.indexedDB.open('products_db', 1);

  // onerror handler signifies that the database didn't open successfully
  request.onerror = function() {
    console.log('Database failed to open');
  } 

  // onsuccess handler signifies that the database opened successfully
  request.onsuccess = function() {
    console.log('Database opened successfully');

    // Store the opened database object in the db variable. This is used a lot below
    db = request.result;

    // Run the fetchProducts() function to fetch data from external API 
    fetchProducts();
  }

  // Setup the database tables if this has not already been done
  request.onupgradeneeded = function(e) {
    // Grab a reference to the opened database
    let db = e.target.result;

    // Create an objectStore to store our products in (basically like a single table)
    // including a auto-incrementing key
    let objectStore = db.createObjectStore('products_os', {keyPath: 'id', autoIncrement: true});

    // Define what data items the objectStore will contain
    objectStore.createIndex('title', 'title', {unique: false});
    objectStore.createIndex('price', 'price', {unique: false});
    objectStore.createIndex('inStock', 'inStock', {unique: false});

  }

  function fetchProducts() {
    let product1 = fetch('http://localhost:3001/fK/affiliate-api.flipkart.net/affiliate/products/1')
      .then(function(response) {
        return response.json();
      })
      .then(function(response) {
        addData(response);
      })
  }

  function addData(value) {
    // open a read/write db transaction, ready for adding the data
    let transaction = db.transaction(['products_os'], 'readwrite');

    // call an object store that's already been added to the database
    let objectStore = transaction.objectStore('products_os');

    let newItem = {
      title: value.productInfoList[0].productBaseInfoV1.title,
      price: value.productInfoList[0].productBaseInfoV1.flipkartSellingPrice.amount,
      inStock: value.productInfoList[0].productBaseInfoV1.inStock,
    };

    // Make a request to add our newItem object to the object store
    var request = objectStore.add(newItem);

    transaction.oncomplete = function() {
      console.log('Transaction completed: database modification finished.');

      // update the display of data to show the newly added item, by running displayData() again.
      displayData();
    }

    transaction.onerror = function() {
      console.log('Transaction not opened due to error');
    };
  }

  function displayData() {
    // Open our object store and then get a cursor - which iterates through all the
    // different data items in the store
    let objectStore = db.transaction('products_os').objectStore('products_os');

    objectStore.openCursor().onsuccess = function(e) {
      // Get a reference to the cursor
      let cursor = e.target.result;

      // Get a reference to table
      let table = document.querySelector('#idb-table');

      // If there is still another data item to iterate through, keep running this code
      if(cursor) {
        // Insert into table, tr and td to put each data item inside when displaying it
        // structure the HTML fragment, and append it inside the table
        let tableRow = document.createElement('tr');
        for (let val in cursor.value) {
          if (Object.prototype.hasOwnProperty.call(cursor.value, val)) {
            if (val !== 'id') {
              let td = document.createElement('td');
              tableRow.appendChild(td);
              td.textContent = cursor.value[val];
            }
          }
        }
        let td = document.createElement('td');
        td.setAttribute('align', 'center');
        let addButton = document.createElement('button');
        td.appendChild(addButton);
        addButton.textContent = 'Add';
        addButton.addEventListener('click', function(e) {
          addCartData(e);
        })
        tableRow.appendChild(td);
        table.appendChild(tableRow);

        // Iterate to the next item in the cursor
        cursor.continue();
      }
    }
  }

  function addCartData(e) {
    let req = window.indexedDB.open('products_db', 2);

    req.onerror = function() {
      console.log('Database failed to open');
    } 

    req.onsuccess = function() {
      console.log('Database opened successfully');

      // Store the opened database object in the db variable. This is used a lot below
      db = request.result;
    }

    req.onblocked = function(event) {
      // If some other tab is loaded with the database, then it needs to be closed
      // before we can proceed.
      alert("Please close all other tabs with this site open!");
    };

    req.onupgradeneeded = function(e){
      var db = e.target.result;
      // Create a cart objectStore
      let cartStore = db.createObjectStore('cart_os', {keyPath: 'idi', autoIncrement: true});

      // Define what data items the cart objectStore will contain
      cartStore.createIndex('title', 'title', {unique: false});
      cartStore.createIndex('price', 'price', {unique: false});
      console.log(db);
    }

    // let items = e.target.parentElement.parentElement.querySelectorAll(':not(:last-child)');

    // let newItem = {title: items[0].textContent, price: items[1].textContent};

    // // open a read/write db transaction, ready for adding the data
    // let transaction = db.transaction(['cart_os'], 'readwrite');

    // // call an object store that's already been added to the database
    // let objectStore = transaction.objectStore('cart_os');

    // // Make a request to add our newItem object to the object store
    // var request = objectStore.add(newItem);
  }
}