如何查询具有不同属性的模型

Question

I'm building an app in Express and using Postgres for my database, Sequelize for ORM.

In my database each Post can have one of the 5 types, 1 , 2 , 3 , 4 , 5 .

I want to show the amount of all the posts by type.

router.route('/post).get(async (req, res) => {
  const postOne = await Post.findAll({
    where: { 
      state: 1
    }
  });
  const postTwo = await Post.findAll({
    where: { 
      state: 2
    }
});
res.send({ postOne: postOne.length, postTwo: postTwo.length });

I can write like this for all of the 5 types, but I was wondering if there was any shorter way to do it so that I don't have to write the same code 5 times.

Thanks!

Answer 1

const getPostWithType = (type) => Post.findAll({
  where: { 
    state: type
  }
});

Now you can await getPostWithType(1) instead. Or even better:

const postTypes = [1,2,3,4,5];
const allPosts = await Promise.all(postTypes.map(getPostWithType));

// allPosts is now an array with the results. You can map it again to get the lengths
const allPostLengths = allPosts.map(p => p.length);

Answer 2

what about using an array? Like below...

 let promiseArray = []; for (let i = 1; i <= 5; i++) { let promise = Post.findAll({ where: { state: i } }); promiseArray.push(promise); } Promise.all(promiseArray).then(function(response) { //Do whatever... });