MongoDB查询处理/获取内部数组（需要在内部数组中应用分页）

Question

我有一个包含如下文档的集合，

Document1:

{
    name: "tester1",
    reports: [{
            name: "report1",
            type: "overflow"
        },
        {
            name: "report2",
            type: "invalid form"
        }
    ]
}

Document2:

{
    name: "tester2",
    reports: [{
            name: "report3",
            type: "crossed"
        },
        {
            name: "report4",
            type: "unknown issue"
        }
    ]
} 

Document3:
{
    name: "tester3",
    reports: [{
            name: "report4",
            type: "try again"
        },
        {
            name: "report6",
            type: "invalid data"
        }
    ]
}

我正在尝试实现查询以获取数据，例如，

[{
        name: "report1",
        type: "overflow"
    },
    {
        name: "report2",
        type: "invalid form"
    },
    {
        name: "report3",
        type: "crossed"
    },
    {
        name: "report4",
        type: "unknown issue"
    },
    {
        name: "report4",
        type: "try again"
    },
    {
        name: "report6",
        type: "invalid data"
    }
]

我尝试使用分组和投影，但无法生成此输出。

我只需要内部数组作为最终文档，这样我就可以应用聚合查询来实现分页和搜索。

Answer 1

您可以使用$unwind 和$replaceRoot 将reports 提升到根级别，然后您可以使用$skip 或$limit：

db.collection.aggregate([
    { $unwind: "$reports" },
    { $replaceRoot: { newRoot: "$reports" } },
    { $limit: 5 }
])

Mongo Playground