A small open-source class library is used to flexibly copy attributes between objects and convert idatareader to object classes.

Function 1:

Background:

This requirement often exists in programming. In two very similar entity classes, copy the value of the attribute with the same name (for example, copying in the WCF entity and EF entity ...)

In the past, there were generally two solutions

1. Hard coding: The execution efficiency is very high, but it requires a lot of repetition.Code,

2. Reflection: flexible, but inefficient

 

Here provides a solution https://github.com/xwj90/Clover.Copyer with no less flexibility than reflection

The code is very simple, as shown below, there is only one sentence

 //Example 1 directly copy attributes on two objects
Classa target =NewClassa ();
Classb source =NewClassb () {A ="AA", B =2, C = datetime. Now };

//Copy code
Copyhelper <classb, classa>. Copy (source, target );//This is the call method.

Console. writeline (target. );
Console. writeline (target. B );
Console. writeline (target. C );
 

The two types are defined as follows:

    Public   Sealed   Class Classa
{

 Public   String A { Get ; Set ;}
 Public   Int B { Get ; Set ;}
 Public   String Title {Get ; Set ;}
 Public   Int Id { Get ; Set ;}
 Public Datetime c { Get ; Set ;}

}
 Public   Sealed   Class Classb
{
 Public   String A { Get ; Set ;}
 Public   Int B { Get ; Set ;}
 Public Datetime c { Get ; Set ;}
}

Note: All types of public instance attributes are supported.

The indexer is not supported.

 

 

Function 2:

Read the corresponding value from the idatareader provided by the database and convert it to the corresponding type and assign it to the object class,

Saving the dataset process in the middle, and saving a lot of work on type conversion and hard coding.

First look at the Code:

             //  Example 2 read attributes from idatareader  
              String Connstring = "  Data Source =.; initial catalog = northwind; persist Security info = true;  " ;
 For ( Int I = 0 ; I < 1 ; I ++)
{

 Using (Sqlconnection conn = New Sqlconnection (connstring ))
{
Sqlcommand command = New Sqlcommand ();
Command. Connection = conn;
Command. commandtext = "  Select Top 1000 * From clog  " ;
Conn. open ();
Idatareader reader = command. executereader ();
 VaR List = copyhelper <testclassa>. Copy (Reader ); //  This is the call method.  
                      Foreach ( VaR Item In List)
{
Console. Write (item. logid + "  ---  " );
Console. Write (item. logtime + " ---  " );
Console. Write (item. appname + "  ---  " );
Console. Write (item. SERVER + "  ---  " );
Console. Write (item. IPaddress + "   " );
Console. writeline ();
}
}
}

Note: All basic types are supported. The order of the columns returned each time is the same. Do not select a, B from table for a while and then select B, A from table for a while (Automatic Detection consumes a lot of performance,)

 

Implementation principle:
Use the Reflection Analysis type for the first time, and then use ilemit to generate a dynamic method

Cache the dynamic method. This method can be used directly for the second time.

 

Performance:

Basically, the efficiency ratio is about

Hard coding: dynamic method: Reflection

--1000 (about 1-30 attributes in the class during actual testing)

 

 

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