1、安装包 MongoDB.Driver

2、定义顶层类

/// <summary>
/// monggodb规范
/// </summary>
public abstract class MongoDBToolBase
{
    /// <summary>
    /// 客户端
    /// </summary>
    protected MongoClient mongoClient { get; private set; }
    /// <summary>
    /// 数据库
    /// </summary>
    protected IMongoDatabase? database;

    /// <summary>
    /// 构造
    /// </summary>
    /// <param name="conn"></param>
    protected MongoDBToolBase(string conn) {
        this.mongoClient = new MongoClient(conn);
    }
}

3、定义操作类

/// <summary>
/// MongoDB 操作类
/// </summary>
public class MongoDBTool<T> : MongoDBToolBase where T : class
{
    /// <summary>
    /// 构造
    /// </summary>
    public MongoDBTool(string conn) : base(conn)
    {
        List<Attribute> attributes
            = typeof(T).GetAttribute().FindAttributeEntity<MongoDBDatabase>();

        if (attributes.Any())
        {
            this.database = this.mongoClient.GetDatabase(((MongoDBDatabase)attributes.First()).name);
        }
        else
        {
            throw new Exception("未找到MongoDBDatabase注解");
        }
    }

    /// <summary>
    /// 得到值
    /// 一个条件
    /// </summary>
    /// <param name="collection">表名</param>
    /// <param name="colName">列名</param>
    /// <param name="value">值</param>
    /// <returns></returns>
    public string GetOneCol(string collection, string colName, string value)
    {
        return this.database?
            .GetCollection<T>(collection)
            .Find<T>(Builders<T>.Filter.Eq(colName, value))
            .ToEnumerable<T>()
            .FirstOrDefault()?
            .ToJson()
            ?? string.Empty;
    }
}

4、定义一个注解，映射mongodb的数据库名称

/// <summary>
/// MongoDB数据库名称
/// </summary>
public class MongoDBDatabase : Attribute
{
    /// <summary>
    /// 名称
    /// </summary>
    public string name { get; set; }

    /// <summary>
    /// 构造
    /// </summary>
    /// <param name="name"></param>
    public MongoDBDatabase(string name)
    {
        this.name = name;
    }
}

5、定义一个实体，映射数据库表字段并且关联对应的数据库

/// <summary>
/// 测试表
/// </summary>
[MongoDBDatabase("test")]
public class MongodbTestModel
{
    /// <summary>
    /// mongoid
    /// </summary>
    public ObjectId _id { get; set; }
    /// <summary>
    /// 名称
    /// </summary>
    public string name { get; set; } = string.Empty;
    /// <summary>
    /// 密码
    /// </summary>
    public string password { get; set; } = string.Empty;
    /// <summary>
    /// 备注
    /// </summary>
    public string rem {  get; set; } = string.Empty;
}

6、ioc注入

//注入mongodb单实例
builder.Services.AddSingleton(new MongoDBTool<MongodbTestModel>(builder.Configuration.GetValue<string>("mongodb")));

7、配置文件

"mongodb": "mongodb://username:password@localhost:27017/?authSource=admin"

8、扩展的注解工具类

/// <summary>
/// 注解工具
/// </summary>
public static class AttributeTool
{
    /// <summary>
    /// 获取注解
    /// </summary>
    /// <param name="cls"></param>
    /// <returns></returns>
    public static List<Attribute> GetAttribute(this Type cls)
    {
        // 获取所有自定义特性（包括注解）
        return cls.GetCustomAttributes().ToList();
    }

    /// <summary>
    /// 看看是否存在有对应注解实体
    /// 存在则返回
    /// </summary>
    /// <typeparam name="T">返回对应的实体数据</typeparam>
    /// <param name="attributes"></param>
    /// <returns></returns>
    public static List<Attribute> FindAttributeEntity<T>(this List<Attribute> attributes)
    {
        List<Attribute> temp = new List<Attribute>();

        Attribute? attribute = attributes.FirstOrDefault(attr =>
        {
            return attr.GetType() == typeof(T);
        });
        
        if (attribute?.IsDefaultAttribute() ?? true)
        {
            return temp;
        }

        temp.Add(attribute);
        
        return temp;
    }
}

9、接口

/// <summary>
/// 查询
/// </summary>
/// <returns></returns>
[HttpPost("search/{name}")]
public string SearchData([FromServices] MongoDBTool<MongodbTestModel> mongoDBTool, string name)
{
    return mongoDBTool.GetOneCol("test", "name", name);
}

都这样了还有什么好说的