Question

我是Mongodb的新手，尝试从集合中获取数据，首先我需要获取数组的所有值＆＃34; 1＆＃34;从下面的例子中，没有传递任何数组值，其次获取Json格式的数据，这将通过游标发送到客户端，toArray函数适用于控制台但不适用于html页面。

代码：

"_id" : ObjectId("5934f65bdab27e02aa954891"),"tracker" : [ 
    {

        "1" : [ 
            "open", 
            "isnot", 
            "closed", 
            "any"
        ],
        "2" : [ 
            "task", 
            "user story", 
            "bug", 
            "support", 
            "feature", 
            "ui modification", 
            "enhancment", 
            "use case"
        ]
    }
],
"subject" : [ 
    {
        "1" : [ 
            "contains", 
            "doesnot contain", 
            "none", 
            "any"
        ]
    }
]}

预期的Output_1（数组的值＆＃34; 1＆＃34;）：＆＃34;打开＆＃34;，＆＃34; is not＆＃34;，＆＃34;关闭＆＃34;，＆＃34;任何＆＃34;

预期的Output_2（Json格式）

"tracker" : [ 
{
    "1" : [ 
        "open", 
        "isnot", 
        "closed", 
        "any"
    ],
    "2" : [ 
        "task", 
        "user story", 
        "bug", 
        "support", 
        "feature", 
        "ui modification", 
        "enhancment", 
        "use case"
    ]
}],"subject" : [ 
{
    "1" : [ 
        "contains", 
        "doesnot contain", 
        "none", 
        "any"
    ]
}]}

Answer 1

db.details.aggregate(

    // Pipeline
    [
        // Stage 1
        {
            $match: {"_id" : ObjectId("5934f65bdab27e02aa954891")}
        },

        // Stage 2
        {
            $unwind: "$tracker"
        },

        // Stage 3
        {
            $project: {
                'tracker.1':1
            }
        },

    ]
);

以上聚合查询在管道中按顺序执行以下聚合阶段

$ match运算符过滤器文档，仅选择文档所在的值 _id字段的等效于特定的对象ID
$ unwind运算符将数组字段拆分为单独的文档数组的每个值。
$ project operator限制返回结果的字段。

MongoDB查询数组元素

1 个答案: