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使用 .NET 在 Azure Cosmos DB for MongoDB 中查询文档

  • 项目

适用对象： MongoDB

使用查询在集合中查找文档。

注意

示例代码片段在 GitHub 上作为 .NET 项目提供。

API for MongoDB 参考文档 | MongoDB 包 (NuGet)

查询文档

要查找文档，请在集合上使用查询筛选器来定义文档的查找方式。

// insert documents to query
var products = new List<BsonDocument>()
{
    new BsonDocument
    {
        { "_id",  new ObjectId("62b1f43a9446918500c875c5") },
        { "name", "Sand Surfboard" },
        { "category", "gear-surfboards" },
        { "count", 1 }
    },
    new BsonDocument
    {
        { "_id",   new ObjectId("12b1f43a9446918500c875c5") },
        { "name", "Ocean Surfboard" },
        { "category", "gear-surfboards" },
        { "count", 5 }
    },
    new BsonDocument
    {
        { "_id",   new ObjectId("55b1f43a9446918500c875c5") },
        { "name", "Beach Towel" },
        { "category", "gear-accessories" },
        { "count", 4 }
    },
    new BsonDocument
    {
        { "_id",   new ObjectId("33b1f43a9446918500c875c5") },
        { "name", "Sunglasses" },
        { "category", "gear-accessories" },
        { "count", 5 }
    }
};

collection.InsertMany(products);

// Find by ID
var filter = Builders<BsonDocument>.Filter.Gt("_id", "62b1f43a9446918500c875c5");
var query1 = collection.Find<BsonDocument>(filter).FirstOrDefault();
Console.WriteLine($"Query by id: {query1["_id"]} \n");

// Find by doc property
var filter2 = Builders<BsonDocument>.Filter.Eq("name", "Sand Surfboard");
var query2 = collection.Find<BsonDocument>(filter2).FirstOrDefault();
Console.WriteLine($"Query by property: {query2["name"]} \n");

// Find all by property
var filter3 = Builders<BsonDocument>.Filter.Eq("category", "gear-surfboards");
var query3 = collection.Find<BsonDocument>(filter3);
Console.WriteLine("Query all by property:");
foreach (var item in query3.ToList())
{
    Console.WriteLine(item["name"]);
}

// Find all in a collection
var query4 = collection.Find<BsonDocument>(new BsonDocument()).ToList();
Console.WriteLine("\nQuery all in a collection:");
foreach (var item in query4.ToList())
{
    Console.WriteLine(item["name"]);
}

// Pagination - fine next 5 docs
// sort by name requires an index on name
var index = Builders<BsonDocument>.IndexKeys.Ascending("name");
collection.Indexes.CreateOne(new CreateIndexModel<BsonDocument>(index));

var sort = Builders<BsonDocument>.Sort.Ascending("name");
var query5 = collection.Find<BsonDocument>(new BsonDocument()).Sort(sort).Skip(2).Limit(2).ToList();
Console.WriteLine("\nQuery using pagination:");
foreach (var item in query5.ToList())
{
    Console.WriteLine(item["name"]);
}

另请参阅