Question

我有一个如下车型

{
    "_id": "54b8a71843286774060b8bed",
    "name": "Car1",
    "active": true,
    "model": [
        {
            "name": "Model1",
            "active": true,
            "_id": "54b8a71843286774060b8bee",
            "available": [
                {
                    "Day": "Mon",
                    "quantity": "6"
                },
                {
                    "Day": "Tue",
                    "quantity": "6"
                },
                {
                    "Day": "Wed",
                    "quantity": "6"
                },
                {
                    "Day": "Thurs",
                    "quantity": "6"
                },
                {
                    "Day": "Fri",
                    "quantity": "0"
                }
            ]
        },
        {
            "name": "Model2",
            "active": true,
            "_id": "54b8a71843286774060b8bef",
            "available": [
                {
                    "Day": "Mon",
                    "quantity": "6"
                },
                {
                    "Day": "Tue",
                    "quantity": "6"
                },
                {
                    "Day": "Wed",
                    "quantity": "6"
                },
                {
                    "Day": "Thurs",
                    "quantity": "6"
                },
                {
                    "Day": "Fri",
                    "quantity": "6"
                }
            ]
        },
        {
            "name": "Model3",
            "active": true,
            "_id": "54b8a71843286774060b8beg",
            "available": [
                {
                    "Day": "Mon",
                    "quantity": "6"
                },
                {
                    "Day": "Tue",
                    "quantity": "6"
                },
                {
                    "Day": "Wed",
                    "quantity": "6"
                },
                {
                    "Day": "Thurs",
                    "quantity": "6"
                },
                {
                    "Day": "Fri",
                    "quantity": "0"
                }
            ]
        }
    ]
}

我正在尝试在特定日期搜索汽车的可用性。就像我选择星期五然后它应该返回我星期五数量超过0的汽车，但目前它将返回所有数量为0的汽车。

我写了如下查询

Car.find（{ '活跃'：是的， 'model.available'：{ $ elemMatch：{ 数量：{$ gte：1} } } }）

但它还返回了数量为0的文件。

Answer 1

为此，您需要aggregation pipeline。

以下代码段执行此操作：

查找至少包含一个匹配模型的所有文档。
拆分文件：一个包含3个模型数组的文档将变成三个文档，每个文档各有一个模型：
{name: "Car1": 1, models: [{name: "Model1"}, {name: "Model2"}, {name: "Model3"}]}
变为：
{name: "Car1", models: {name: "Model1"}}＆amp; {name: "Car1", models: {name: "Model2"}}＆amp; {name: "Car1", models: {name: "Model3"}}。
在数量和日期过滤（再次）拆分文件。
或者，再次将文档粘合在一起。您可能不需要在您的应用程序中使用它。

db.cars.aggregate([
    // First, we do your query, which will return 
    // every document that has _at least one_
    // model that is available.
    {$match: {
        'active': true,
        'model.available': {$elemMatch: { 
            'quantity': {$gte: 1},
            'Day': 'Fri'
        }}
    }},
    // We split up the found documents,
    // every document will now have exactly
    // one 'model' in it.
    {$unwind: "$model"},
    // We now filter the split documents.
    {$match: {
        'model.available': {$elemMatch: { 
            'quantity': {$gte: 1},
            'Day': 'Fri'
        }}
    }},
    // If you want, you can now glue the
    // models back together again.
    {$group: {
        _id:    "$_id", // Group all documents with the same _id
        name:   {$first: "$name"},
        active: {$first: "$active"},
        model:  {$push: "$model"}  // Make an array of models
    }}
])

重要说明：要使$gte生效，您需要将数量存储为数字，而不是字符串。由于您的示例将数字存储为字符串，因此您可能需要在数据库中仔细检查它们。

在嵌套文档上使用mongoose / mongoDB查询

1 个答案: