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  • 4.2 数组查询

    老规矩,先添加数据

    var documents = new[]
    {
        new BsonDocument
        {
            { "item", "journal" },
            { "qty", 25 },
            { "tags", new BsonArray { "blank", "red" } },
            { "dim_cm", new BsonArray { 14, 21 } }
        },
        new BsonDocument
        {
            { "item", "notebook" },
            { "qty", 50 },
            { "tags", new BsonArray { "red", "blank" } },
            { "dim_cm", new BsonArray { 14, 21 } }
        },
        new BsonDocument
        {
            { "item", "paper" },
            { "qty", 100 },
            { "tags", new BsonArray { "red", "blank", "plain" } },
            { "dim_cm", new BsonArray { 14, 21 } }
        },
        new BsonDocument
        {
            { "item", "planner" },
            { "qty", 75 },
            { "tags", new BsonArray { "blank", "red" } },
            { "dim_cm", new BsonArray { 22.85, 30 } }
        },
        new BsonDocument
        {
            { "item", "postcard" },
            { "qty", 45 },
            { "tags", new BsonArray { "blue" } },
            { "dim_cm", new BsonArray { 10, 15.25 } }
        }
    };
    collection.InsertMany(documents);
    

    匹配整个数组

    //语法
    Builders<BsonDocument>.Filter.Eq(<field>, <value>)
    //实例
    var filter = Builders<BsonDocument>.Filter.Eq("tags", new[] { "red", "blank" });
    var result = collection.Find(filter).ToList();
    //匹配的时候是完全匹配,包括顺序
    //但是有时候你希望查询包含了red和blank两个元素,而且不考虑先后顺序,那么使用all 操作符
    eg:
    var filter = Builders<BsonDocument>.Filter.All("tags", new[] { "red", "blank" });
    var result = collection.Find(filter).ToList();

    查询数组中的一个元素

    //语法
    Builders<BsonDocument>.Filter.Eq(<field>, <value>)
    //实例
    var filter = Builders<BsonDocument>.Filter.Eq("tags", "red");
    var result = collection.Find(filter).ToList();
    
    //使用查询操作符 语法
    var builder = Builders<BsonDocument>.Filter;
    builder.And(builder.Eq(<array field>, <value1>), builder.Lt(<array field>, <value2>));
    //实例
    var filter = Builders<BsonDocument>.Filter.Gt("dim_cm", 25);
    var result = collection.Find(filter).ToList();
    

    多个条件查询数组

    //使用混合过滤条件
    var builder = Builders<BsonDocument>.Filter;
    var filter = builder.And(builder.Gt("dim_cm", 15), builder.Lt("dim_cm", 20));
    var result = collection.Find(filter).ToList();
    
    //使用 $elemMatch operator 
    var filter = Builders<BsonDocument>.Filter.ElemMatch<BsonValue>("dim_cm", new BsonDocument { { "$gt", 22 }, { "$lt", 30 } });
    var result = collection.Find(filter).ToList();

    参考地址:https://docs.mongodb.com/manual/reference/operator/query/elemMatch/#op._S_elemMatch

    依靠数组位置查询元素

    var filter = Builders<BsonDocument>.Filter.Gt("dim_cm.1", 25);
    var result = collection.Find(filter).ToList();

    查询数组的长度

    var filter = Builders<BsonDocument>.Filter.Size("tags", 3);
    var result = collection.Find(filter).ToList();
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  • 原文地址:https://www.cnblogs.com/maanshancss/p/12978142.html
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