使用C＃创建MongoDB唯一密钥

我是MongoDB的总计n00b，我正在努力创建一个独特的字段EmailAddress。我已经在论坛上看到我必须创建一个索引，但到目前为止还没有为我提供帮助。有没有人有代码示例？我是否必须在每次保存/调用时创建索引，还是只创建一次就足够了？使用C＃创建MongoDB唯一密钥

我试过这段代码：

DB.GetCollection<User>(Dbname) 
    .EnsureIndex(new IndexKeysBuilder() 
     .Ascending("EmailAddress"), IndexOptions.SetUnique(true)); 

DB.GetCollection<User>(Dbname).Save(user, SafeMode.True);

我User模式是这样的：

public class User 
{ 
    [Required(ErrorMessage = "Email Required")] 
    public string EmailAddress { get; set; } 

    public ObjectId Id { get; set; } 

    public string FirstName { get; set; } 
    public string LastName { get; set; } 
}

来源

2011-06-02 Uter1007

这你用的是驱动程序？ – atbebtg 2011-06-02 22:38:41

您的代码看起来正确。这是一个完整的运行程序为您比较：

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Text; 

using MongoDB.Bson; 
using MongoDB.Driver; 
using MongoDB.Driver.Builders; 

namespace TestEnsureIndexOnEmailAddress { 
    public class User { 
     public ObjectId Id; 
     public string FirstName; 
     public string LastName; 
     public string EmailAddress; 
    } 

    public static class Program { 
     public static void Main(string[] args) { 
      var server = MongoServer.Create("mongodb://localhost/?safe=true"); 
      var database = server["test"]; 
      var users = database.GetCollection<User>("users"); 
      if (users.Exists()) { users.Drop(); } 

      users.EnsureIndex(IndexKeys.Ascending("EmailAddress"), IndexOptions.SetUnique(true)); 
      var john = new User { FirstName = "John", LastName = "Smith", EmailAddress = "[email protected]" }; 
      users.Insert(john); 
      var joe = new User { FirstName = "Joe", LastName = "Smith", EmailAddress = "[email protected]" }; 
      users.Insert(joe); // should throw exception 
     } 
    } 
}

您还可以使用蒙戈外壳，以确认该指数得到了创建：

> db.users.getIndexes() 
[ 
     { 
       "name" : "_id_", 
       "ns" : "test.users", 
       "key" : { 
         "_id" : 1 
       }, 
       "v" : 0 
     }, 
     { 
       "_id" : ObjectId("4de8152ee447ad2550e3b5fd"), 
       "name" : "EmailAddress_1", 
       "ns" : "test.users", 
       "key" : { 
         "EmailAddress" : 1 
       }, 
       "unique" : true, 
       "v" : 0 
     } 
] 
>

来源

2011-06-02 22:59:19

其工作正常，但我想两个或更多的领域，以减少重复。建议我 – 2017-06-06 06:18:18

唯一索引只需要创建一次，之后，包含重复电子邮件地址的任何文档插入将失败。这里有一个例子：

var server = MongoServer.Create("mongodb://localhost"); 
var db = server.GetDatabase("myapp"); 

var users = db.GetCollection<User>("users"); 

users.EnsureIndex(new IndexKeysBuilder() 
    .Ascending("EmailAddress"), IndexOptions.SetUnique(true)); 

var user1 = new User { EmailAddress = "[email protected]" }; 
var user2 = new User { EmailAddress = "[email protected]" }; 

try 
{ 
    users.Save(user1, WriteConcern.Acknowledged); 
    users.Save(user2, WriteConcern.Acknowledged); // <-- throws MongoSafeModeException 
} 
catch (MongoSafeModeException ex) 
{ 
    Console.WriteLine(ex.Message); 
}

来源

2011-06-02 23:01:03

EnsureIndex（）已过时/每C＃蒙戈驱动程序版本过时的2.0规范：http://api.mongodb.org/csharp/current/html/M_MongoDB_Driver_MongoCollection_EnsureIndex_2.htm

继承人如何做到这一点异步，并通过2.0代码：

var mongoClient = new MongoClient("connection"); 
var db = mongoClient.GetDatabase("database"); 

var options = new CreateIndexOptions() { Unique = true }; 
var field = new StringFieldDefinition<User>("EmailAddress"); 
var indexDefinition = new IndexKeysDefinitionBuilder<User>().Ascending(field); 
await db.GetCollection<Users>("users").Indexes.CreateOneAsync(indexDefinition, options);

来源

2015-06-23 21:32:57 kennydust

使用C＃创建MongoDB唯一密钥

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