Question

给出这样的集合：..

[
  {
    "_id" : ObjectId("5546329a470000850084a621"),
    "name": "Joe",
    "surname": "Smith",
    "accounts": [
      {
        "_id" : ObjectId("5546329a470000850084a655"),
        "default": true,
        "status" : "approved",
        "activationTime" : ISODate("2013-05-03T14:37:15.025Z")
      },
      {
        "_id" : ObjectId("5546329a470000850084a688"),
        "default": true,
        "status" : "approved",
        "activationTime" : ISODate("2014-06-03T14:37:15.025Z")
      }
    ]
  },
  {
    "_id" : ObjectId("9546329a470079850084a622"),
    "name": "Jimmy",
    "surname": "Brown",
    "accounts": [
      {
        "_id" : ObjectId("5546329a470790850084a651"),
        "default": true,
        "status" : "suspended",
        "activationTime" : ISODate("2015-02-03T14:37:15.025Z")
      },
      {
        "_id" : ObjectId("5546329a470019850084a611"),
        "default": true,
        "status" : "approved",
        "activationTime" : ISODate("2015-04-03T14:37:15.025Z")
      }
    ]
  },
]

...如何找到accounts.N._id的文件？我试过这个......

db.users.find(
  {},
  {
    "accounts": 0, "accounts": {
      "$elemMatch": { "_id" : ObjectId("5546329a470019850084a611"), "default": true }
    }
  }
)

...但由于我只收到所有文件的_id，所以它不起作用：

{ "_id" : ObjectId("5546329a470000850084a621") }
{ "_id" : ObjectId("9546329a470079850084a622") }

我错过了什么吗？

修改

我实际需要的结果是这样的：

{
  "_id" : ObjectId("9546329a470079850084a622"),
  "name": "Jimmy",
  "surname": "Brown"
}

例如，我需要通过accounts.N._id查找，但不显示嵌套文档本身。

Answer 1

使用dot notation：

当该字段包含嵌入的文档时，查询可以指定嵌入文档的完全匹配或指定匹配嵌入文档中的各个字段使用点表示法。

jQuery.sap.declare("app.Component");
//jQuery.sap.require("app.MyRouter");

sap.ui.core.UIComponent.extend("app.Component", {
    metadata: {
        name: "DEmo App",
        version: "1.0",
        includes: [],
        dependencies: {
            libs: ["sap.m", "sap.ui.layout"], //add any other libraries you need
            components: []
        },

        //rootView : "app.view.App",

        config: {
            resourceBundle: "i18n/i18n.properties",
            //if you have service
            /*serviceConfig : {
                name: "SERVICE_NAME",
                serviceUrl: "/your/service/url/"
            }*/
        },

        routing: {

            routes: [
              //your routes
      ]
        }
    },

    init: function () {
        sap.ui.core.UIComponent.prototype.init.apply(this, arguments);

        var mConfig = this.getMetadata().getConfig();

        // Always use absolute paths relative to our own component
        // (relative paths will fail if running in the Fiori Launchpad)
        var oRootPath = jQuery.sap.getModulePath("app");

        // Set i18n model
        var i18nModel = new sap.ui.model.resource.ResourceModel({
            bundleUrl: [oRootPath, mConfig.resourceBundle].join("/")
        });
        this.setModel(i18nModel, "i18n");

        var sServiceUrl = mConfig.serviceConfig.serviceUrl;

        //This code is only needed for testing the application when there is no local proxy available
        var bIsMocked = jQuery.sap.getUriParameters().get("responderOn") === "true";
        // Start the mock server for the domain model
        if (bIsMocked) {
            this._startMockServer(sServiceUrl);
        }

        // Create and set domain model to the component
        var oModel = new sap.ui.model.odata.ODataModel(sServiceUrl, {
            json: true,
            loadMetadataAsync: true
        });

        // if you have static models
        //  var oModel = new sap.ui.model.odata.ODataModel([oRootPath, "model/coffee.json"].join("/"), {json: true,loadMetadataAsync: true});
        this.setModel(oModel);

        // Set device model if needed
        var oDeviceModel = new sap.ui.model.json.JSONModel({
            isTouch: sap.ui.Device.support.touch,
            isNoTouch: !sap.ui.Device.support.touch,
            isPhone: sap.ui.Device.system.phone,
            isNoPhone: !sap.ui.Device.system.phone,
            listMode: sap.ui.Device.system.phone ? "None" : "SingleSelectMaster",
            listItemType: sap.ui.Device.system.phone ? "Active" : "Inactive"
        });
        oDeviceModel.setDefaultBindingMode("OneWay");
        this.setModel(oDeviceModel, "device");

        //this.getRouter().initialize();

    }
});

如果您只需输出数组中有_id的部分，则需要使用dollar in projection

位置$运算符限制了a的内容查询结果只包含与查询匹配的第一个元素文档。

，您的查询将如下所示：

db.coll.find({
   "accounts._id" :ObjectId("5546329a470019850084a611")
})

P.S。如果你需要像你修改过的问题那样输出，请使用：

db.coll.find({
   "accounts._id" :ObjectId("5546329a470019850084a611")
}, {
   "accounts.$.": 1
})

Answer 2

$ elemMatch运算符将查询结果中字段的内容限制为仅包含与$ elemMatch条件匹配的第一个元素。

在你的情况下：

<string name="hello">Bonjour</string>

参考：Mongo Docs

Answer 3

在条件中使用$elemMatch并在项目中使用$位置运算符，如下所示：

db.users.find({
  "accounts": {
    "$elemMatch": {
      "_id": ObjectId("5546329a470019850084a611"),
      "default": true
    }
  }
}, {
  "accounts.$._id": 1 // "accounts.$": 1 also works
}).pretty()

MongoDB：如何通过嵌套文档中的id查找文档

3 个答案: