Using EF and C # generics to implement Universal paging queries

using EF and C # generics to implement universal paging queriesThe Entity Framework is Microsoft's ORM framework, an object-relational correspondence (ORM) solution developed on the basis of ADO. This framework associated the table information in the database with the entity class object through XML, so that developers only need to care about the entity object, without needing to manipulate the database manually, the modification of the entity object will be mapped to the database, which greatly improves the development efficiency. The following code uses the EF, generics, generics delegate, Lambda, anonymous class, dynamic type, and other knowledge to complete the crud of EF, and provides an efficient universal paging query method that takes a deferred load and the return value type is IQueryable.

1 usingSystem;2 usingSystem.Collections.Generic;3 usingSystem.Data.Entity;4 usingSystem.Linq;5 usingSystem.Linq.Expressions;6 usingSystem.Text;7 8 namespaceeftest9 {Ten     class Program One     { A         Static voidMain (string[] args) -         { -Testentities context =Newtestentities (); the  -             //Increase -             //t_test T = new T_test () {name= "Kobayashi"};  -             //context. T_test.add (t); +             //context. SaveChanges (); -  +  A             //Delete at             //Lambda mode -             //var t = context. T_test.where (u=> (u.id==1)). FirstOrDefault (); -  -             //LINQ to SQL mode -             //var t = (from u in context. T_test -             //where u.id = = 1 in             //select u). FirstOrDefault (); -             //context. T_test.remove (t); to             //context. SaveChanges (); +             //the deletion of data is more convenient and more efficient in this way -             //t_test T = new T_test () {id=2}; the             //context. Entry<t_test> (T). state=entitystate.deleted; *             //context. SaveChanges (); $ Panax Notoginseng             //Change -             //var t = (from u in context. T_test the             //where u.id = = 2 +             //select u). FirstOrDefault (); A             //t.name = "Xiao Lin"; the             //context. SaveChanges (); +  -             //Check $             //var t = (from u in context. T_test $             //where u.id = = 2 -             //select u). FirstOrDefault (); -             //Console.WriteLine (t.id + t.name); the              -             //General Page PagingWuyi             intcount;  theGetpagelistparameter<t_test,int> parameter=NewGetpagelistparameter<t_test,int>(); -Parameter.isasc=true; WuParameter.orderbylambda = s = =s.id; -Parameter.pageindex =1; AboutParameter.pagesize =3; $Parameter.selectlambda = s = =NewPerson{name=S.name}; -Parameter.wherelambda = s = = s.id >3; -  -             vardata = Getpagelist<t_test,int> (parameter, outcount); A  +             foreach(Person tinchdata) the             { - Console.WriteLine (t.name); $             } the  the Console.readkey (); the         } the  -          Public StaticList<dynamic> getpagelist<t, tkey> (getpagelistparameter<t, tkey> parameter, out intCountwhereT:class in         { theTestentities context =Newtestentities (); the             //Note Order AboutCount = context. Set<t> (). Where<t>(PARAMETER.WHERELAMBDA). Count (); the             varList = context. Set<t> (). Where<t>(PARAMETER.WHERELAMBDA); the             if(PARAMETER.ISASC) the             { +List =list. (PARAMETER.ORDERBYLAMBDA); -             } the             ElseBayi             { theList =list. OrderByDescending (PARAMETER.ORDERBYLAMBDA); the             } -  -             returnList. Skip ((Parameter.pageindex-1) *parameter.pagesize). Take (parameter.pagesize). Select (PARAMETER.SELECTLAMBDA). ToList (); the         } the     } the  the     //take the required columns -      Public class Person the     { the          Public stringName {Get;Set; } the     }94  the     //Encapsulation Method Parameters the      Public classGetpagelistparameter<t, tkey> the     {98          PublicExpression<func<t, dynamic>> Selectlambda {Get;Set; } About          PublicExpression<func<t,BOOL>> Wherelambda {Get;Set; } -          PublicExpression<func<t, tkey>> Orderbylambda {Get;Set; }101          Public intpageSize {Get;Set; }102          Public intPageIndex {Get;Set; }103          Public BOOLISASC {Get;Set; }104     } the}

Using EF and C # generics to implement Universal paging queries