使用Mongodb C＃在列表數組中查找值

Question

我下面有JSON數據。 我想搜索一個EmpId並返回一條記錄。

我正在使用下面的代碼，但它返回所有EmpId。

我想搜索一個emp Id（例如100），查詢應返回EMpId等於100的記錄？

{
"EmpInfo": {
   "DeptId":"C0",
   "Employee":[
                {
                      "EmpId":"100",
                      "isActive": true,
                      "Name":"smith"

                },{
                      "EmpId":"101",
                      "isActive": true,
                       "Name":"John"

                },
                {
                      "EmpId":"102",
                      "isActive": true,
                        "Name":"Sam"

                }
            ]
        }
}

C＃代碼：找到emp ID = 100

 var collection = _mongoDataClient.client.GetDatabase("Dbname");
 var builder = Builders<EmpInfoData>.Filter;
  FilterDefinition<EmpInfoData> filter;

  foreach (var rid in _CatalogInfoRequest.EmpInfo.Employee)
   {
   filter = Builders<EmpInfoData>.Filter.ElemMatch(x => x.Employee, x => x.railId == rid.EmpId);
      filter = builder.Eq("Employee.EmpId", 100);

      List <EmpInfoData> dashboardContents = null;
        result = collection.Find(filter).ToList();


            if (result [0].Employee.Count > 0)
             {
                   strmessage = "Update:"+result [0].children.Count; //Should return single count but returning 3 rows.
              }

}

Answer 1

我認為您正在用下面的代碼行覆蓋ElemMatch過濾器：

filter = Builders<EmpInfoData>.Filter.ElemMatch(x => x.Employee, x => x.railId == rid.EmpId);
filter = builder.Eq("Employee.EmpId", 100); // Overrides what you did in the previous line

嘗試刪除第二行。

希望能幫助到你！

Answer 2

我得到了解決方案，我寫了如下的過濾查詢，它工作正常。

 var Queryfilter = Builders<EmpInfoData>.Filter.And(
                 Builders<EmpInfoData>.Filter.ElemMatch(x => x.Employee, r => r.EmpId == rid.EmpId));