javascript - 对 Sequelize 中的链式 promise 使用 then promise 时 undefined object

Question

我正在使用以下代码对 Sequelize 中的 invoice 对象使用链式 promise 。但是 invoice 对象对于 then 的第二次使用是未定义的。

Invoice.create({
    //set values for invoice object
}).then(invoice => { //update company id
    //invoice belongs to a company
    Company.findOne({where: {id: companyId}}).then(company => {
        return invoice.setCompany(company)
    })
}).then(invoice => {
    console.log('Invoice is: ' + invoice)
    //create child items
    invoice.createItem({
        //set item values
    })
}).catch(err => {
    console.log('Invoice create error: ' + err)
})

控制台中的输出是 Invoice is :undefined 。我在这里做错了什么？

Answer 1

那是因为您需要在第一个 .then 回调中返回 promise 。

改变这个:

Invoice.create({
    //set values for invoice object
}).then(invoice => { //update company id
    //invoice belongs to a company
    Company.findOne({where: {id: companyId}}).then(company => {
        return invoice.setCompany(company)
    })
}).then(...)

至:

Invoice.create({
    //set values for invoice object
}).then(invoice => { 
    // return this promise
    return Company.findOne({where: {id: companyId}}).then(company => {
        invoice.setCompany(company)
        // you also need to return your invoice object here
        return invoice
    })
}).then(...)