MongoDB-获取确切的数组元素，不包括其他元素 [英] MongoDB- Fetching exact array element, excluding others

问题描述

我是MongoDB的新手，正在尝试执行查询以从数据库中找到匹配的文本.下面是提到的细节-

I am new to MongoDB and trying to execute a query to find a matching text from a database. Below are the details mentioned -

使用MongoDB，我试图获取带注释的标注为DATA NOT FOUND的文本. 通过我的查询，我得到的所有记录的备注都为DATA NOT FOUND以及备注为TOO_MANY_DATA. 请参考数据库中存在的以下数据-

Using MongoDB, I am trying to fetch the annotated texts having remarks as DATA NOT FOUND. With my query, I am getting all the records having remarks as DATA NOT FOUND as well as remarks as TOO_MANY_DATA. Please refer to the below data present in the database-

输入-

{
    "_id" : ObjectId("aaaaaaaaaaaa"),
    "projectDR" : "123456789",
    "code" : "RRR",
    "fileName" : "123456789_1.xml",
    "specFileDivNumber" : "050000",
    "normalizationStatus" : "ASDWFGL",
    "divisionIn" : {
        "sections" : [ 
            {
                "sectionNumber" : "050000",
                "sectionName" : "textile",
                "labels" : [ 
                    {
                        "normalizedDate" : ISODate("2018-10-28"),
                        "remarks" : "DATA NOT FOUND",
                        "bod" : false,
                        "ID" : "4048",
                        "annotatedText" : "Mains"
                    }, 
                    {
                        "normalizedDate" : ISODate("2018-10-28"),
                        "remarks" : "DATA NOT FOUND",
                        "bod" : false,
                        "ID" : "4064",
                        "annotatedText" : "routong"
                    }, 
                    {
                        "prefCode" : "ABC00000890",
                        "prefLabel" : "ABCRTYYUUUU",
                        "normalizedDate" : ISODate("2018-10-28"),
                        "remarks" : "TOO_MANY_DATA",
                        "bod" : false,
                        "ID" : "15736",
                        "annotatedText" : "Uniform"
                    },

                ]
            }
        ]
    },
    "status" : "Success",
    "fileDate" : ISODate("2018-10-28"),
    "Type" : "History"
}

查询-db.getCollection('BasicInfo').find({'divisionIn.sections.labels.remarks':'DATA NOT FOUND'})

预期输出:

{
    "_id" : ObjectId("aaaaaaaaaaaa"),
    "projectDR" : "123456789",
    "code" : "RRR",
    "fileName" : "123456789_1.xml",
    "specFileDivNumber" : "050000",
    "normalizationStatus" : "ASDWFGL",
    "divisionIn" : {
        "sections" : [ 
            {
                "sectionNumber" : "050000",
                "sectionName" : "textile",
                "labels" : [ 
                    {
                        "normalizedDate" : ISODate("2018-10-28"),
                        "remarks" : "DATA NOT FOUND",
                        "bod" : false,
                        "ID" : "4048",
                        "annotatedText" : "Mains"
                    }, 
                    {
                        "normalizedDate" : ISODate("2018-10-28"),
                        "remarks" : "DATA NOT FOUND",
                        "bod" : false,
                        "ID" : "4064",
                        "annotatedText" : "routong"
                    },                    
                ]
            }
        ]
    },
    "status" : "Success",
    "fileDate" : ISODate("2018-10-28"),
    "Type" : "History"
}

请帮助我更正查询，以便获得期望的结果.

Please help me to correct the query so as to get the expected.

推荐答案

这是对MongoDB的一种标准且可理解的数组错误观念.查询条件将产生范围为 document 的适当结果，而不必 just 您要查找的数组中的项目.换句话说，给定您希望找到DATA NOT FOUND的目标，大多数简单查询都会找到数组中至少一项匹配的任何文档-但不会过滤掉不匹配的文档.您必须稍微复杂一点才能做到这一点:

This is a standard and understandable array-of-array misconception with MongoDB. The query criteria will yield the proper result scoped to a document, not necessarily just the items in an array you are looking for. In other words, given your desired goal of finding DATA NOT FOUND, most simple queries will find any document where at least one item in the array matches -- but will not filter out those that do not. You have to get a little more complex to do this in one shot:

db.foo.aggregate([
// Make sure at *least* one label has a remark of DATA NOT FOUND;
// otherwise, the $filter trick in the next stage yields a labels array
// of length 0 (which is not horrible).  Also, this is a good place to
// add other $match criteria, possibly index-optimized, to shrink down the
// size of response set:
{$match: {"divisionIn.sections.labels.remarks":"DATA NOT FOUND"}}

,{$project: {
        // Copy over the main doc level things we want:
        projectDR: "$projectDR",
        code: "$code",
        status: "$status"

        // divisionIn is a map, not an array, so we can dive down using dot notation
        // and make a new sections array called divSections that will ONLY have
        // DATA NOT FOUND: 
        divSections: {$map: {input: "$divisionIn.sections", as:"z", in:
            {
                // Again, copy over things we want to keep; may not need all of them
                "sectionNumber": "$$z.sectionNumber",
                "sectionName": "$$z.sectionName",

                // The Juice: Copy BUT FILTER the labels field conditionally based on
                // the value of labels.remarks:
                "labels": {$filter: {input: "$$z.labels",
                             as: "z2",
                             cond: {$eq: [ "$$z2.remarks", "DATA NOT FOUND"] }
                    }}
            }
            }}
    }}

                       ]);

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