如何通过 C# 将包含数据的新列插入 MongoDB 中的集合？

Question

我有两个字段需要比较并相应地采取行动：

if(x == y) then x = [new Field called Z]
else [new Field called Z] = Math.Random

如何使用 MongoDB 在 C# 中执行此操作？

Answer 1

假设您将以下实体 class Item 定义为：

public class Item
{
    [BsonId]
    public String Id {get; set;}

    public int a {get; set;}

    public int x {get; set;}

    public int y {get; set;}
}

使用 MongoDB C# Driver, you could start by retrieving the two fields you want using SetFields method of MongoCursor class:

var server = MongoServer.Create(connectionString);
var db = server.GetDatabase("dbName");
MongoCollection collection = db.GetCollection<Item>("items");

MongoCursor<Item> cursor = collection.FindAs<Item>(Query.EQ("a", 33)); //if you want to match specific docs else Query.Null
cursor.SetFields(Fields.Include("x", "y"));
var items = cursor.ToList();
foreach (var item in items)
{
    // compare item.x and item.y and act accordingly
}

从这里您可以遍历游标，进行比较。如果您想在要插入新字段的地方执行更新操作 z 那么这应该有效

collection.Update(Query.Null, Update.Set("z", Math.Random), UpdateFlags.Multi)

如何通过 C# 将包含数据的新列插入 MongoDB 中的集合？

How can I insert a new column with data to a collection in MongoDB, through C#?

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