Smark.Data实体默认值描述
在数据设计的时候会针对一些字段设置默认的值,Smark.Data同样支持这样的功能,组件通过在属性中描述一个Value属性来告诉组件这个值如果在没有设置的情况应该提供怎样的值。组件提供一个描述的基类,用户可以根据实际情况的需要扩展出具体的默认值描述,以下是值描述基础类:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | [AttributeUsage(AttributeTargets.Property)] public abstract class ValueAttribute:Attribute { public ValueAttribute( bool afterupdate) { AfterByUpdate = afterupdate; } public bool AfterByUpdate { get ; set ; } public virtual void Executing(IConnectinContext cc, object data,PropertyMapper pm, string table) { } public virtual void Executed(IConnectinContext cc, object data, PropertyMapper pm, string table) { } } |
基础类有两个方法,一个是描述在数据操作前要做的工作,一个是描述数据操作后需要完成的工作。一般设置默认值都在数据操作之前的,为什么还要定义一个操作后的呢。其实有些情况的确要在数据操作后做,如果MSSQL自增ID就是添加后把相关ID值设置到对象中,这个时候就需要在数据操作完成后进行:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | [AttributeUsage(AttributeTargets.Property)] public class IDENTITY : ValueAttribute { public IDENTITY() : base ( true ) { } public override void Executed(IConnectinContext cc, object data, PropertyMapper pm, string table) { Command cmd = new Command( "select @@IDENTITY " ); object value = cc.ExecuteScalar(cmd); pm.Handler.Set(data,Convert.ChangeType( value,pm.Handler.Property.PropertyType)); } } |
如果想给一个属性设置一个默认的GUID值,用于主键可以这样做
1 2 3 4 5 6 7 8 9 10 | [AttributeUsage(AttributeTargets.Property)] public class UID:ValueAttribute { public UID() : base ( false ) { } public override void Executing(IConnectinContext cc, object data, PropertyMapper pm, string table) { string uid = Guid.NewGuid().ToString( "N" ); pm.Handler.Set(data, uid); } } |
可以通过以下定义引用UID属性
1 2 3 | [ID] [UID] string EmployeeID { get ; set ; } |
在这基础上可以实现很多需要的默认值,以下是组件内部实现的默认值描述类
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 | [AttributeUsage(AttributeTargets.Property)] public class YearMonth : ValueAttribute { public YearMonth() : base ( false ) { } public override void Executing(IConnectinContext cc, object data, PropertyMapper pm, string table) { pm.Handler.Set(data, DateTime.Now.Year.ToString( "0000" ) + DateTime.Now.Month.ToString( "00" )); } } [AttributeUsage(AttributeTargets.Property)] public class Year : ValueAttribute { public Year() : base ( false ) { } public override void Executing(IConnectinContext cc, object data, PropertyMapper pm, string table) { pm.Handler.Set(data, DateTime.Now.Year.ToString()); } } [AttributeUsage(AttributeTargets.Property)] public class Month : ValueAttribute { public Month() : base ( false ) { } public override void Executing(IConnectinContext cc, object data, PropertyMapper pm, string table) { pm.Handler.Set(data, DateTime.Now.Month.ToString()); } } [AttributeUsage(AttributeTargets.Property)] public class Day : ValueAttribute { public Day() : base ( false ) { } public override void Executing(IConnectinContext cc, object data, PropertyMapper pm, string table) { pm.Handler.Set(data, DateTime.Now.Day.ToString()); } } [AttributeUsage(AttributeTargets.Property)] public class NowDate:ValueAttribute { public NowDate() : base ( false ) { } public override void Executing(IConnectinContext cc, object data, PropertyMapper pm, string table) { pm.Handler.Set(data, DateTime.Now); } } [AttributeUsage(AttributeTargets.Property)] public class DefaultInt : ValueAttribute { private int mValue = 0; public DefaultInt( int value) : base ( false ) { mValue = value; } public override void Executing(IConnectinContext cc, object data, PropertyMapper pm, string table) { pm.Handler.Set(data, mValue); } } [AttributeUsage(AttributeTargets.Property)] public class DefaultDecimal : ValueAttribute { private decimal mValue = 0; public DefaultDecimal( string value) : base ( false ) { mValue = Convert.ToDecimal(value); } public override void Executing(IConnectinContext cc, object data, PropertyMapper pm, string table) { pm.Handler.Set(data,mValue); } } [AttributeUsage(AttributeTargets.Property)] public class DefaultString : ValueAttribute { private string mValue = "" ; public DefaultString( string value) : base ( false ) { mValue = value; } public override void Executing(IConnectinContext cc, object data, PropertyMapper pm, string table) { pm.Handler.Set(data, mValue); } } [AttributeUsage(AttributeTargets.Property)] public class DefaultDate:ValueAttribute { private DateTime mValue = DateTime.MinValue; public DefaultDate( string value) : base ( false ) { mValue =DateTime.Parse(value); } public override void Executing(IConnectinContext cc, object data, PropertyMapper pm, string table) { pm.Handler.Set(data, mValue); } } [AttributeUsage(AttributeTargets.Property)] public class Enabled : ValueAttribute { public Enabled() : base ( false ) { } public override void Executing(IConnectinContext cc, object data, PropertyMapper pm, string table) { pm.Handler.Set(data, true ); } } |
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