LINQ dynamic orderby sorting

Method:

///   <Summary>
/// Extended sorting of linqstring Fields
///   </Summary>
Public Static Class Stringfieldsorting
{
# Region Private Expression Tree helpers
Private Static Lambdaexpression generateselector <tentity> (string propertyname, Out Type resulttype) Where Tentity: Class
{
Propertyinfo property;
Expression propertyaccess;
VaR Parameter = expression. parameter ( Typeof (Tentity ), " Entity " );

If (Propertyname. Contains ( ' . ' ))
{
String [] childproperties = propertyname. Split ( ' . ' );
Property = Typeof (Tentity). getproperty (childproperties [ 0 ]);
Propertyaccess = expression. makememberaccess (parameter, property );
For ( Int I = 1 ; I <childproperties. length; I ++)
{
Property = property. propertytype. getproperty (childproperties [I]);
Propertyaccess = expression. makememberaccess (propertyaccess, property );
}
}
Else
{
Property = Typeof (Tentity). getproperty (propertyname );
Propertyaccess = expression. makememberaccess (parameter, property );
}

Resulttype = property. propertytype;

Return Expression. Lambda (propertyaccess, parameter );
}
Private Static Methodcallexpression generatemethodcall <tentity> (iqueryable <tentity> source, String Methodname, string fieldname) Where Tentity: Class
{
Type type = Typeof (Tentity );
Type selectorresulttype;
Lambdaexpression selector = generateselector <tentity> (fieldname, Out Selectorresulttype );
Methodcallexpression resultexp = expression. Call ( Typeof (Queryable), methodname,
New Type [] {type, selectorresulttype },
Source. expression, expression. Quote (selector ));
Return Resultexp;
}
# Endregion

Public Static Iorderedqueryable <tentity> orderby <tentity> ( This Iqueryable <tentity> source, String Fieldname) Where Tentity: Class
{
Methodcallexpression resultexp = generatemethodcall <tentity> (source, " Orderby " , Fieldname );
Return Source. provider. createquery <tentity> (resultexp) As Iorderedqueryable <tentity>;
}

Public Static Iorderedqueryable <tentity> orderbydescending <tentity> ( This Iqueryable <tentity> source, String Fieldname) Where Tentity: Class
{
Methodcallexpression resultexp = generatemethodcall <tentity> (source, " Orderbydescending " , Fieldname );
Return Source. provider. createquery <tentity> (resultexp) As Iorderedqueryable <tentity>;
}

Public Static Iorderedqueryable <tentity> thenby <tentity> ( This Iorderedqueryable <tentity> source, String Fieldname) Where Tentity: Class
{
Methodcallexpression resultexp = generatemethodcall <tentity> (source, " Thenby " , Fieldname );
Return Source. provider. createquery <tentity> (resultexp) As Iorderedqueryable <tentity>;
}

Public Static Iorderedqueryable <tentity> thenbydescending <tentity> ( This Iorderedqueryable <tentity> source, String Fieldname) Where Tentity: Class
{
Methodcallexpression resultexp = generatemethodcall <tentity> (source, " Thenbydescending " , Fieldname );
Return Source. provider. createquery <tentity> (resultexp) As Iorderedqueryable <tentity>;
}
Public Static Iorderedqueryable <tentity> orderusingsortexpression <tentity> ( This Iqueryable <tentity> source, String Sortexpression) Where Tentity: Class
{
String [] orderfields = sortexpression. Split ( ' , ' );
Iorderedqueryable <tentity> result = Null ;
For ( Int Currentfieldindex = 0 ; Currentfieldindex <orderfields. length; currentfieldindex ++)
{
String [] expressionpart = orderfields [currentfieldindex]. Trim (). Split ( '   ' );
String sortfield = expressionpart [ 0 ];
Boolean sortdescending = (expressionpart. Length = 2 ) & (Expressionpart [ 1 ]. Equals ( " Desc " , Stringcomparison. ordinalignorecase ));
If (Sortdescending)
{
Result = currentfieldindex = 0 ? Source. orderbydescending (sortfield): result. thenbydescending (sortfield );
}
Else
{
Result = currentfieldindex = 0 ? Source. orderby (sortfield): result. thenby (sortfield );
}
}
Return Result;
}
}

Call:

VaR Query = ( From D In (Vinnotech. gaia2.db. g2_dsource []) result)
Join P In Webapiapplication. Entities. g2_propnames
On D. dsource_item equals P. prop_name
Orderby Sidx
Select New
{
D. dsource_id,
D. dsource_name,
Dsource_item = P. prop_description,
D. dsource_description,
Dsource_status = D. dsource_status = " 1 " ? " Enable " : " Disable " ,
D. dsource_expiredday,
Dsource_alarmhigh = (D. dsource_alarmhigh =- 65535 | D. dsource_alarmhigh = 65535 )? " Disabled " : D. dsource_alarmhigh.tostring (),
Dsource_alarmlow = (D. dsource_alarmlow =- 65535 | D. dsource_alarmhigh = 65535 )? " Disabled " : D. dsource_alarmhigh.tostring (),
Dsource_alarmdeltadata = (D. dsource_alarmdeltadata =- 65535 | D. dsource_alarmhigh = 65535 )? " Disabled " : D. dsource_alarmhigh.tostring (),
Dsource_alarmidle = (D. dsource_alarmidle =- 65535 | D. dsource_alarmhigh = 65535 )? " Disabled " : D. dsource_alarmhigh.tostring (),
D. dsource_formula,
Dsource_updatetime = D. dsource_updatetime.tostring ( " Yyyy-mm-dd hh: mm: SS " )
}). Asqueryable ();

Page = page <= query. Count ()/rows + 1 ? Page: 1 ;

Query = query. orderusingsortexpression ("Dsource_name ASC, dsource_item DESC"). Skip (rows * (page-1). Take (rows );