今天寫了一個數(shù)據(jù)庫的幫助類，代碼如下。?

1 public static class DbEx 2 { 3 public static dynamic ReadToObject(this IDataReader reader) 4 { 5 var obj = new DbObject(); 6 7 for (int i = 0; i < reader.FieldCount; i++) 8 { 9 obj[reader.GetName(i)] = new DbField() 10 { 11 DbData = reader[i] 12 }; 13 } 14 15 return obj; 16 } 17 18 public class DbObject : DynamicObject 19 { 20 //自己實現(xiàn)一個，不用ExpandoObject， 以支持無視大小寫讀取 21 public override bool TryGetMember(GetMemberBinder binder, out object result) 22 { 23 result = this[binder.Name]; 24 return true; 25 } 26 27 Dictionary<string, object> _values = new Dictionary<string, object>(StringComparer.CurrentCultureIgnoreCase); 28 29 public object this[string index] 30 { 31 get => _values[index]; 32 set => _values[index] = value; 33 } 34 } 35 36 public class DbField 37 { 38 public object DbData { get; set; } 39 40 public T Value<T>() 41 { 42 return (T)Convert.ChangeType(DbData, typeof(T)); 43 } 44 45 public static implicit operator string(DbField data) => data.Value<string>(); 46 public static implicit operator int(DbField data) => data.Value<int>(); 47 public static implicit operator DateTime(DbField data) => data.Value<DateTime>(); 48 public static implicit operator double(DbField data) => data.Value<double>(); 49 public static implicit operator bool(DbField data) => data.Value<bool>(); 50 } 51 } View Code

簡單的來講，可以把如下代碼

GpsData parse(IDataReader reader)
{
????return new GpsData()
????{
????????IsValid = (bool)reader["IsValid"],
????????Location = new Location ()
????????{
????????????Lon = (double)reader["Lon"],
????????????Lat = (double)reader["Lat"],
????????},
????????Angle = (double)reader["Angle"],
????????Speed = (double)reader["Speed"]),
????????UpdateTime = (double)reader["Speed"]),
????};
}

轉(zhuǎn)換為如下形式

GpsData parse(IDataReader reader)
{
????var obj = reader.ReadToObject();
????var state = new GpsData()
????{
????????IsValid = obj.IsValid,
????????Location = new Location()
????????{
????????????Lon = obj.Lon,
????????????Lat = obj.Lat,
????????},
????????Angle = obj.Angle,
????????Speed = obj.Speed,
????????UpdateTime = obj.UpdateTime,
????};
????return state;
}

主要還是利用dynamic的特性，轉(zhuǎn)換成這樣的好處有：

以屬性的方式替換下標方式讀取，更加間接直觀

屬性的方式讀取變量時不分大小寫

支持自動類型轉(zhuǎn)換，例如，如果數(shù)據(jù)庫里的類型是int型，而目標是string型，會進行自動類型轉(zhuǎn)換

自動識別目標類型，不需要顯示強制類型轉(zhuǎn)換，更加簡潔

總結(jié)

以上是生活随笔為你收集整理的利用dynamic简化数据库的访问的全部內(nèi)容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網(wǎng)站內(nèi)容還不錯，歡迎將生活随笔推薦給好友。