python - 返回 mongodb 中的某些字段

Question

我试图只返回满足我的条件的数组。这是我所拥有的:

{
"_id": 1,
"awardAmount": 20000,
"url": "www.url.com",
"numAwards": 2,
"award": "Faculty Research Grant",
"Type": "faculty",
"Applicants": [
    {
        "preAwards": "NO1",
        "Name": "Omar1",
        "School": "SCSU1",
        "citizenship": "YES1",
        "budget": 1,
        "Advisor": "Dr. DaPonte1",
        "Major": "CSC1",
        "appId": 100,
        "Research": "Test data entry1",
        "Time": "12 months1",
        "URL": "www.url.com",
        "Evaluators": [
            {
                "abstractScore": 11,
                "evalNum": 1,
                "goalsObjectivesScore": 11
            },
            {
                "abstractScore": 22,
                "evalNum": 2,
                "goalsObjectivesScore": 22
            }
        ]
    },
    {
        "preAwards": "NO2",
        "citizenship": "YES2",
        "Major": "CSC2",
        "Time": "12 months2",
        "budget": 2,
        "URL": "www.2.com",
        "appId": 200,
        "Advisor": "Dr. DaPonte2",
        "Name": "Omar2",
        "Research": "Test data entry2",
        "School": "SCSU2",
        "url": "www.2.com"
    },
    {
        "preAwards": "NO3",
        "citizenship": "YES3",
        "Major": "CSC3",
        "Time": "12 months3",
        "budget": 3,
        "URL": "www.3.com",
        "appId": 300,
        "Advisor": "Dr. DaPonte3",
        "Name": "Omar3",
        "Research": "Test data entry3",
        "School": "SCSU3",
        "url": "www.3.com",
        "Evaluators": [
            {
                "abstractScore": 454,
                "evalNum": 1,
                "goalsObjectivesScore": 4546
            }
        ]
    }
]
}

我只想返回没有 Evaluators 字段的申请人。

{
"_id": 1,
"awardAmount": 20000,
"url": "www.url.com",
"numAwards": 2,
"award": "Faculty Research Grant",
"Type": "faculty",
"Applicants": [
    {
        "preAwards": "NO2",
        "citizenship": "YES2",
        "Major": "CSC2",
        "Time": "12 months2",
        "budget": 2,
        "URL": "www.2.com",
        "appId": 200,
        "Advisor": "Dr. DaPonte2",
        "Name": "Omar2",
        "Research": "Test data entry2",
        "School": "SCSU2",
        "url": "www.2.com"
    }
]
}

这只是一个文档的示例。我希望所有文档中的所有申请人都没有评估员字段。

Answer 1

将聚合与 pymongo 结合使用

col.aggregate([{"$unwind": "$Applicants"}, {"$match" : {"Applicants.Evaluators": {"$exists": False}}}]))

输出

{'ok': 1.0,
 'result': [{'Applicants': {'Advisor': 'Dr. DaPonte2',
                            'Major': 'CSC2',
                            'Name': 'Omar2',
                            'Research': 'Test data entry2',
                            'School': 'SCSU2',
                            'Time': '12 months2',
                            'URL': 'www.2.com',
                            'appId': 200,
                            'budget': 2,
                            'citizenship': 'YES2',
                            'preAwards': 'NO2',
                            'url': 'www.2.com'},
             'Type': 'faculty',
             '_id': 1,
             'award': 'Faculty Research Grant',
             'awardAmount': 20000,
             'numAwards': 2,
             'url': 'www.url.com'}]}