.net core MongoDB 初试

是这样的，我们有一个场景，另一个服务器是写到MongoDB里面，我们的MVC页面要展示，需要分页展示

自己写了一个DAL

   public class MongoConnect
    {
        public string ConnectString { get; set; }
    }

    public class MongoBaseDAL<TEntity>
    {
        public MongoBaseDAL(IOptions<MongoConnect> options)
        {
            ConnectString = options.Value.ConnectString;
        }

        private string ConnectString { get; set; } = "192.168.50.110:27017";

        protected MongoClient Create()
        {
            var client = new MongoClient($"mongodb://{ConnectString}");
            return client;
        }

        protected IMongoDatabase GetDatabase(string database)
        {
            var client = Create();
            var db = client.GetDatabase(database);

            return db;
        }

        protected IMongoCollection<TEntity> CreateQuery(string database,string tableName)
        {
            var db = GetDatabase(database);
            return db.GetCollection<TEntity>(tableName);
        }

        protected PageDataView<TEntity> Page(string database, string tableName, Dictionary<string, BsonValue> dictionary, int pageSize, int currentPage)
        {
            var where = Builders<TEntity>.Filter.Empty;
            if (dictionary.Count > )
            {
                var filterBuilder = Builders<TEntity>.Filter;

                List<FilterDefinition<TEntity>> listFilter = new List<FilterDefinition<TEntity>>();

                foreach (var pair in dictionary)
                {
                    listFilter.Add(filterBuilder.Eq(pair.Key, pair.Value));
                }

                where = filterBuilder.And(listFilter);
            }

            PageDataView<TEntity> result = new PageDataView<TEntity>();

            var query = CreateQuery(database, tableName);
            result.TotalRecords = (int)query.CountDocuments(where);
            result.TotalPages = result.TotalRecords / pageSize;
            if (result.TotalRecords % pageSize > )
                result.TotalPages += ;

            var list = query.Find(where).Skip((currentPage - ) * pageSize).Limit(pageSize).ToList();
            result.Items = list;

            return result;
        }
    }

比如有个类CreatedTableLog

那个Helper就是

    public class CreatedTableLogHelper: MongoBaseDAL<CreatedTableLog>
    {
        public static string Database = "Base";
        public static string Table = "CreatedTableLog";

        public CreatedTableLogHelper(IOptions<MongoConnect> options) : base(options)
        {
        }

        public PageDataView<CreatedTableLog> GetListByPage(Dictionary<string, BsonValue> dictionary, int pageSize, int currentPage)
        {
            return Page(Database, Table, dictionary, pageSize, currentPage);
        }
    }

在StartUp里面增加代码

            #region MongoDB
            services.Configure<MongoConnect>(Configuration.GetSection("MongoConnect"));
            services.AddScoped(typeof(MongoBaseDAL<>));
            services.AddScoped<CreatedTableLogHelper>();
            #endregion

打开配置文件

appsettings.Development.json这个是DEBUG版本的配置文件

写入配置

  "MongoConnect": {
    "ConnectString": "192.168.50.110:27017"
  }

192.168.50.110是我测试环境是MongoDB服务器地址，端口默认

appsettings.Development.json这个是Release版本的配置文件可能这个地址就是localhost了，要对应更改

比如CreatedTableLog表有三个字段

UserId和NickName需要查询

            Dictionary<string, BsonValue> dictionary = new Dictionary<string, BsonValue>();

            var index = model.Start ==  ?  : (model.Start / model.Length) + ;

            if (model.UserId != )
            {
                dictionary.Add("UserId", BsonInt64.Create(model.UserId));
            }

            if (!string.IsNullOrWhiteSpace(model.NickName))
            {
                dictionary.Add("NickName", BsonString.Create(model.NickName));
            }

            var result = CreatedTableLogHelper.GetListByPage(dictionary, model.Length, index);

这样你以为就ok了？no no no

会报错的，为什么同一个实体model，写入正常，读会报错_id错误呢？

因为实体model如果没有Id类型是ObjectId，会自动构建，但是你反序列化就会错误了

增加一个继承类

    public class MongoDbBase
    {
        private ObjectId _id;
        public ObjectId Id
        {
            get { return _id; }
            set { _id = value; }
        }
    }

你需要反序列化的实体对象继承

比如CreatedTableLog改为

public class CreatedTableLog: MongoDbBase

再读一下，对了吧？大功告成