从Pymongo结果中删除_id元素 [英] Removing _id element from Pymongo results

问题描述

我正在尝试使用MongoDB和Flask(使用pymongo驱动程序)创建Web服务.当然，对数据库的查询将返回包含"_id"字段的文档.我不想将其发送给客户端，那么如何删除它?

I'm attempting to create a web service using MongoDB and Flask (using the pymongo driver). A query to the database returns documents with the "_id" field included, of course. I don't want to send this to the client, so how do I remove it?

这是一条烧瓶路线:

@app.route('/theobjects')
def index():
    objects = db.collection.find()
    return str(json.dumps({'results': list(objects)}, 
        default = json_util.default,
        indent = 4))

这将返回:

{
"results": [
    {
        "whatever": {
            "field1": "value", 
            "field2": "value", 
        }, 
        "whatever2": {
            "field3": "value"
        },
        ...
        "_id": {
            "$oid": "..."
        }, 

    ...
    }
]}

我认为这是一本字典，我可以在返回它之前删除该元素:

I thought it was a dictionary and I could just delete the element before returning it:

del objects['_id']

但是返回TypeError:

But that returns a TypeError:

TypeError: 'Cursor' object does not support item deletion

所以它不是字典，但是我必须将每个结果作为字典进行迭代.因此，我尝试使用以下代码来做到这一点:

So it isn't a dictionary, but something I have to iterate over with each result as a dictionary. So I try to do that with this code:

for object in objects:
    del object['_id']

每个对象字典看起来都像我现在想要的那样，但是对象光标为空.因此，我尝试创建一个新字典，并从每个字典中删除_id之后，将其添加到Flask将返回的新字典中:

Each object dictionary looks the way I'd like it to now, but the objects cursor is empty. So I try to create a new dictionary and after deleting _id from each, add to a new dictionary that Flask will return:

new_object = {}
for object in objects:
    for key, item in objects.items():
        if key == '_id':
            del object['_id']
            new_object.update(object)

这仅返回具有第一级键的字典，仅此而已.

This just returns a dictionary with the first-level keys and nothing else.

所以这是一个标准的嵌套字典问题，但令我感到震惊的是MongoDB没有一种轻松解决此问题的方法.

So this is sort of a standard nested dictionaries problem, but I'm also shocked that MongoDB doesn't have a way to easily deal with this.

MongoDB文档解释说，您可以排除_id与

The MongoDB documentation explains that you can exclude _id with

{ _id : 0 }

但这与pymongo无关. Pymongo文档解释说您可以列出要返回的字段，但(("_id"将始终包含))".严重地?有没有办法解决这个问题?我在这里忽略了一些简单而愚蠢的事情吗?

But that does nothing with pymongo. The Pymongo documentation explains that you can list the fields you want returned, but "("_id" will always be included)". Seriously? Is there no way around this? Is there something simple and stupid that I'm overlooking here?

推荐答案

要在pymongo的查找查询中排除_id字段，可以使用:

To exclude the _id field in a find query in pymongo, you can use:

db.collection.find({}, {'_id': False})

此文档在说服力上有些误导，因为它说总是包含_id字段.但是您可以像上面显示的那样排除它.

The documentation is somewhat missleading on this as it says the _id field is always included. But you can exclude it like shown above.

这篇关于从Pymongo结果中删除_id元素的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！