如何使用express.js和react.js删除联接表中的元素和关联元素

Question

我有一个项目，其中有两个主表：Contacts和Workers

我还有一个名为WorkerContacts 的联接表

在我的项目中，我为用户提供了删除联系人的选项，这也需要删除联接表的元素。我担心的是，在我目前的设置中(如下所示(，如果我遇到一个错误，我成功地删除了一个联系人，但随后未能删除相关联的联接表(这是由于一个错误造成的(，那么一切都会被丢弃。因此，我的问题是，有没有一种方法可以重构它，从而确保在进行实际删除之前，都已经完成了，然后将承诺发送到前端？

以下是我目前的情况：

前端：

export const destroyContact = (contact_id) => dispatch => {

axios.post(`http://localhost:3001/contacts/destroy`, {id: contact_id})
.then(() => {
dispatch({type: 'CONTACT_DESTROYED', payload: contact_id});
axios.post(`http://localhost:3001/workerContacts/destroy`, {id: contact_id}) //I'm scared that the first thing will run but the second one won't, causing a lot of problems. We can deal with this by just throwing a big error message for the user hopefully
.then(() => {
dispatch({type: 'JOIN_TABLE_ROWS_DESTROYED', payload: contact_id});
})
.catch(err => dispatch({type: 'ERROR_CAUGHT', payload: {err_message: err.response.data.message, err_code: err.response.request.status, err_value: err.response.request.statusText}}))

})
.catch(err => dispatch({type: 'ERROR_CAUGHT', payload: {err_message: err.response.data.message, err_code: err.response.request.status, err_value: err.response.request.statusText}}))
}

我也在使用redux，所以这就是为什么我有所有的调度等等，但本质上我已经将删除划分为两个axios调用：一个是我删除联系人的调用，另一个是删除联接表的调用。

后端：

对于联系人，我有这个：

export const destroy = (req, res) => {
// Here is when we want to remove an existing contact
Contact.deleteMe(req.body.id)
.then(() => res.json("Contact deleted"))
.catch((err) => res.status(500).json({message: "Something went wrong when trying to save delete this. Try and reload the page and try again "}))
}

以及相关的deleteMe函数：

static deleteMe(customer_id){
//Uses SQL to delete an individual customer element
return db.execute('DELETE FROM contacts WHERE id = ?', [customer_id]);
}

对于联合体，我有这个：

export const destroy = (req, res) => {
// Here is when we want to remove an existing contact
JoinTable.deleteMe(req.body.id)
.then(() => res.json("Join tables deleted"))
.catch(err => res.status(500).json({message: "Something went wrong on our end. Try to reload the page and start again"}))
}

以及相关的deleteMe函数：

static deleteMe(customer_id){
//Uses SQL to delete an individual customer element
return db.execute('DELETE FROM workercontacts WHERE workerContacts.contact_id = ?', [customer_id]);
}

如果有帮助的话，我会使用MySQL数据库。

希望这是足够的信息，但如果你需要更多，我绝对可以提供给你。

Answer 1

只需使用一个调用并在事务中执行DELETE命令：

export const destroyContact = (contact_id) => (dispatch) => {
axios
.post(`http://localhost:3001/contacts/destroy`, { id: contact_id })
.then(() => {
dispatch({ type: 'CONTACT_DESTROYED', payload: contact_id });
dispatch({ type: 'JOIN_TABLE_ROWS_DESTROYED', payload: contact_id });
})
.catch((err) =>
dispatch({
type: 'ERROR_CAUGHT',
payload: {
err_message: err.response.data.message,
err_code: err.response.request.status,
err_value: err.response.request.statusText,
},
})
);
};

一个后端：

static async function deleteMe(customer_id) {
await db.execute('START TRANSACTION');
try {
await db.execute('DELETE FROM contacts WHERE id = ?', [customer_id]);
await db.execute('DELETE FROM workercontacts WHERE workerContacts.contact_id = ?', [customer_id]);
await db.execute('COMMIT');
} catch (err) {
await db.execute('ROLLBACK');
}
}
...
export const destroy = (req, res) => {
// Here is when we want to remove an existing contact
Contact.deleteMe(req.body.id)
.then(() => res.json("Contact deleted"))
.catch((err) => res.status(500).json({message: "Something went wrong when trying to save delete this. Try and reload the page and try again "}))
}