Promise 返回到分辨率之前

Question

I have books object having data stored in file. I am reading data from each file and creating books.

Here issue is createBooks promise then is getting called before completion of reading file and success of createBook method call.

  createBooks: function (books) {
    return new Promise((resolve, reject) => {
        const booksArray = Object.entries(books);
        const aPromises = [];
        booksArray.forEach(([key, value]) => {          
            if(value.data){
                const oFileReader = new FileReader();
                oFileReader.readFile(value.data)
               .then((product) => {
                aPromises.push(this.Service.createBook(books));
               });
            }
        });
        Promise.all(aPromises)
            .then(results => resolve(results))
            .catch(error => reject());
        });
  },

Answer 1

Try to log aPromises array values before Promise.all(aPromises) . Are there Promise<> objects?

What does the this.Service.createBook(books) return?

FileReader does not have readFile method.

You should use oFileReader.onload handler

oFileReader.onload = function(){
    aPromises.push(this.Service.createBook(books));
};

oFileReader.readAsDataURL(value.data); // value.data - has to be File
// oFileReader.readAsText(value.data); // value.data - has to be blob