pymongo-如何匹配查找? [英] pymongo - how to match on lookup?

问题描述

我有两个集合，一个模型和一个论文集合.我需要能够匹配他们两个的字段.它们有一个共同的字段，称为引用，其中包含一个标识符.

I have two collections, a model and a papers collection. I need to be able to match fields from both of them. They have a field in common called reference which contains an identifier.

我要匹配具有以下内容的文档

I want to match documents that have the following

'作者':论文集中的'Migliore M' 'celltypes':模型集合中的'海马CA3锥体细胞'

'authors' : 'Migliore M' from the papers collection 'celltypes' : 'Hippocampus CA3 pyramidal cell' from the models collection

这是我的代码的样子:

pipeline = [{'$lookup': 
                {'from' : 'models',
                 'localField' : 'references',
                 'foreignField' : 'references',
                 'as' : 'cellmodels'}},
             {'$match':
                 {'authors' : 'Migliore M', 'cellmodels.celltypes' : 'Hippocampus CA3 pyramidal cell'}},


             ]

for doc in (papers.aggregate(pipeline)):
    pprint (doc)

我没有结果.

我注意到，如果不在match参数中调用cellmodels.celltypes，它将找到与Migliore M匹配的论文.我如何才能使其也与细胞类型匹配:模型中的海马CA3锥体细胞"该查询中的收藏吗?

I notice that if I do not call on the cellmodels.celltypes in the match parameter it will find the papers that match Migliore M. How can I get it to also match the celltype:'Hippocampus CA3 pyramidal cell' from the models collection in this query?

推荐答案

此方法有效:

pipeline = [{'$lookup': 
                {'from' : 'models',
                 'localField' : '_id',
                 'foreignField' : 'references',
                 'as' : 'cellmodels'}},
            {'$unwind': '$cellmodels'},
             {'$match':
                 {'authors' : 'Migliore M', 'cellmodels.celltypes' : 'Hippocampus CA3 pyramidal cell'}},
            {'$project': 
                {'authors':1, 'cellmodels.celltypes':1}} 
             ]

for doc in (papers.aggregate(pipeline)):
    pprint (doc)

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