如何将一个int切片传递给"$ in"使用mgo [英] How to pass an int slice to "$in" using mgo

问题描述

使用mgo的bson功能创建查询时遇到了一些麻烦.我只是尝试做{'search_id': {'$in': [1,2,4,7,9]}}，但是我不知道如何在mgo中做到这一点.

I'm having a bit of trouble creating a query using the bson functionality of mgo. I'm simply trying to do {'search_id': {'$in': [1,2,4,7,9]}}, but I can't work out how to do it in mgo.

我有一个int片，并尝试直接传递它:

I have a slice of ints, and tried passing that directly:

toRemove := []int{1,2,4,7,9}
err = coll.Remove(bson.M{"search_id": bson.M{"$in": toRemove}})

我看到了另一则帖子，提示我需要使用[]interface{}，但这也不起作用:

I saw another post which suggested I needed to use []interface{}, but that doesn't work either:

toRemoveI := make([]interface{}, len(toRemove))
for idx, val := range toRemove {
    toRemoveI[idx] = val
}
err = coll.Remove(bson.M{"search_id": bson.M{"$in": toRemoveI}})

我在这里和gh上浏览了他的文档和其他问题，但是大多数涉及切片的问题似乎都是关于将数据放入切片中，而不是我要实现的目标.

I've looked through he docs and other questions here and on gh, but most questions involving slices seem to be about getting data into a slice as opposed to what I'm trying to achieve.

任何帮助将不胜感激.

推荐答案

您的原始提案(传递[]int值)没有缺陷，这样做是有效的.

Your original proposal (passing an []int value) has no flaws, it's valid to do that.

问题是您使用 Collection.Remove() 它会查找并删除与提供的选择器文档匹配的单个文档.因此，您建议的解决方案将删除恰好1个文档，该文档的search_id包含在您传递的切片中.如果找不到此类文档(会话处于安全模式，请参见 )，返回 mgo.ErrNotFound .

What the problem is is that you use Collection.Remove() which finds and removes a single document matching the provided selector document. So your proposed solution will remove exactly 1 document, one whose search_id is contained in the slice you passed. If no such document is found (and the session is in safe mode, see Session.SetSafe()), mgo.ErrNotFound is returned.

请使用 Collection.RemoveAll() 来查找并删除所有与选择器匹配的文档:

Instead use Collection.RemoveAll() which finds and removes all documents matching the selector:

toRemove := []int{1,2,4,7,9}
info, err := c.RemoveAll(bson.M{"search_id": bson.M{"$in": toRemove}})

if err != nil {
    log.Printf("Failed to remove: %v", err)
} else {
    log.Printf("Removed %d documents.", info.Removed)
}

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