Set Default Value in EF4

Set the default value for a property of an object

Model:

 

Weight is an empty property of product. Right-click weight to view the property. The default value is set in default value.

 

Code

Using (Efdemoentities Context =   New Efdemoentities ())
{

Product =   New Product
{
Productname =   " Big Pear " ,
Unitprice =   3 ,
Color =   " White "
};
Context. Products. addobject (product );
Context. savechanges ();
}

 

 

The result is as follows:

 

 

Set the default value for the null attribute during query.

Code

// LINQ
Using (VAR Context =   New Efdemoentities ())
{
Console. writeline ( " Products: " );
VaR Products = From P In Context. Products
Select New {Productname = P. productname, weight = P. Weight ??   0 };
Foreach (VAR Product In Products)
{
Console. writeline ( " {0}, weight: {1} " , Product. productname, product. weight );
}
}

// Esql
Using (VAR Context =   New Efdemoentities ())
{
Console. writeline ( " Products: " );
String Esql =   @" Select
P. productname,
Case when P. weight is null then 0
Else P. Weight
End as productweight
From products as P " ;
VaR Products = Context. createquery < Dbdatarecord > (Esql );
Foreach (VAR Product In Products)
{
Console. writeline ( " {0}, weight: {1} " , Product. getstring ( 0 ), Product. getdouble ( 1 ));
}
}

 

 

The result is as follows (the default value is 0 ):