CODEWITHSUNDEEP
node.jspromisesails.jswaterlinebluebird
Murat Ozgul
Murat Ozgul

Reputation: 11781

Conditionally create new entries using promises in Waterline (Sails.js)

I have an array of "products". I want to save these products to the database if the database is empty, and when all of the db operations finish i want to display a message.

I could not manage to do it using bluebird promises (using .all or .map). I was able to create an item by just returning Product.create(products[0]). I can't wrap my head around it, I am new to promises.

This is the bootstrap file of my sails.js project but this question is about how to use bluebird promises. How can I manage to wait for multiple async tasks (create 3 products) to finish and then continue?

  products = [
    {
      barcode: 'ABC',
      description: 'seed1',
      price: 1
    },
    {
      barcode: 'DEF',
      description: 'seed2',
      price: 2
    },
    {
      barcode: 'GHI',
      description: 'seed3',
      price: 3
    }
  ];


  Product.count()
  .then(function(numProducts) {
    if (numProducts > 0) {
      // if database is not empty, do nothing
      console.log('Number of product records in db: ', numProducts);
    } else {
      // if database is empty, create seed data
      console.log('There are no product records in db.');

      // ???
      return Promise.map(function(product){
        return Product.create(product);
      });
    }
  })
  .then(function(input) {
    // q2) Also here how can decide to show proper message
    //console.log("No seed products created (no need, db already populated).");
    // vs
    console.log("Seed products created.");
  })
  .catch(function(err) {
    console.log("ERROR: Failed to create seed data.");
  });

Upvotes: 0

Views: 271

Answers (1)

Murat Ozgul
Murat Ozgul

Reputation: 11781

Figured it out...

  products = [
    {
      barcode: 'ABC',
      description: 'seed1',
      price: 1
    },
    {
      barcode: 'DEF',
      description: 'seed2',
      price: 2
    },
    {
      barcode: 'GHI',
      description: 'seed3',
      price: 3
    }
  ];


  Product.count()
  .then(function(numProducts) {
    //if (numProducts > 0) {
    if(false) {
      // if database is not empty, do nothing
      console.log('Number of product records in db: ', numProducts);
      return [];
    } else {
      // if database is empty, create seed data
      console.log('There are no product records in db.');
      return products;
    }
  })
  .map(function(product){
    console.log("Product created: ", product);
    return Product.create(product);
  })
  .then(function(input) {
    console.log("Seed production complete.");
  })
  .catch(function(err) {
    console.log("ERROR: Failed to create seed data.");
  });

Upvotes: 1

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