node.js 猫鼬查找和删除
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Mongoose Find and Remove
提问by Micha Schwab
I'm trying to delete multiple documents that satisfy a query. However I need the data of those documents for storing them in a separate collection for undo functionality. The only way I got this to work is with multiple queries:
我正在尝试删除满足查询的多个文档。但是，我需要将这些文档的数据存储在单独的集合中以实现撤消功能。我让它工作的唯一方法是使用多个查询：
Data.find(query).exec(function(err, data)
{
Data.remove(query).exec(function(err2)
{
ActionCtrl.saveRemove(data);
});
});
Is there a better way? In this post: How do I remove documents using Node.js Mongoose?it was suggested to use find().remove().exec():
有没有更好的办法？在这篇文章中：如何使用 Node.js Mongoose 删除文档？建议使用 find().remove().exec():
Data.find(query).remove().exec(function(err, data)
{
ActionCtrl.saveRemove(data);
});
However datais usually 1, don't ask me why. Can I do this without infinitely nesting my queries? Thanks!
但是data通常是1，不要问我为什么。我可以在不无限嵌套查询的情况下执行此操作吗？谢谢！
回答by snozza
As you have noted, using the following will not return the document:
正如您所指出的，使用以下内容不会返回文档：
Data.find(query).remove().exec(function(err, data) {
// data will equal the number of docs removed, not the document itself
}
As such, you can't save the document in ActionCtrlusing this approach.
因此，您无法ActionCtrl使用此方法保存文档。
You can achieve the same result using your original approach, or use some form of iteration. A control flow library like asyncmight come in handy to handle the async calls. It won't reduce your code, but will reduce the queries. See example:
您可以使用原始方法或使用某种形式的迭代来获得相同的结果。像async这样的控制流库可能会派上用场来处理异步调用。它不会减少您的代码，但会减少查询。见示例：
Data.find(query, function(err, data) {
async.each(data, function(dataItem, callback) {
dataItem.remove(function(err, result) {
ActionCtrl.saveRemove(result, callback);
});
});
});
This answer assumes that the ActionCtrl.saveRemove()implementation can take an individual doc as a parameter, and can execute the callback from the async.eachloop. async.eachrequires a callback to be run without arguments at the end of each iteration, so you would ideally run this at the end of .saveRemove()
这个答案假设ActionCtrl.saveRemove()实现可以将单个文档作为参数，并且可以从async.each循环中执行回调。async.each需要在每次迭代结束时不带参数地运行回调，因此您最好在结束时运行它.saveRemove()
Note that the removemethod on an individual document will actually return the document that has been removed.
请注意，remove单个文档上的方法实际上将返回已删除的文档。
