(MVC) MVC (2017 год)

Amazing extension function CopyLinqDataMembersByName to expand Linq-to-SQL.

I think Linq-To-SQL is great framework, if you don't plan use фnother server than MS SQL. And I continue extend I think Linq-To-SQL is great framework, if you don't plan use another server than MS SQL. Therefore I been continue extend this framework with new functions. Some my extensions I had described in page Five amazing Linq-to-SQL extension. In this page I will tell about my new amazing extension. But first of all I describing an environment where this extension is absolutely must.

In three screenshort below you may see absolutelly common pattern of ASP.NET programming.



This is most common template of ASP.NET programming and using Linq-to-SQL. And generally not need anything another to write code inside ASP.NET control.

But this approach has a big problem, first of it that one item of construction, that return Linq-to-SQL not be a serialized and not be stored to Viewstate.

And I have second big problem - in my project I have big existing control (with more than 500 strings of code), and I don't want to change all this code, I want to create small path over this code. Historically this control had working with stupid construction like in screen below.



And previous programmer of this project binded this control to DataRow, that he produced with big list of DataSet (XSD-files).



If he loading XSD-result to control's repiter dataset, he does not another way than contruction like dtProddetails.Rows(i).Item("ProductId") or DabinderEval like in screensort above.

I don't want to learn currefully existung 530 string of code, I want to change DataSet-framework to Linq-to-SQL framework and I search a way to simple transform stupid construction from untyped dataset with string name with parentheses of fields to typed Linq-to-SQL name of fields. And second problem for refactoring of this code is permanently changing DB fields name, therefore I want to statically fix some names, what need to working control correctly.

For solve this problem, I found thais solution.

If you can read my article for this place, you are ready to understand simple thing - no way alternative to function below.

So, this is my amazing function to expand Linq-to-SQL world.



   1:  Imports Microsoft.VisualBasic
   2:   
   3:  Public Module Extension4
   4:   
   5:      <Runtime.CompilerServices.Extension()> _
   6:      Public Function CopyLinqDataMembersByName(Of targetClass)(dc As Data.Linq.DataContext, sourceEntity As Object, targetEntity As targetClass) As targetClass
   7:   
   8:          Dim SourceMembers As IEnumerable(Of Data.Linq.Mapping.MetaDataMember) = _
   9:          From SourceOne In dc.Mapping.GetTable(sourceEntity.[GetType]()).RowType.DataMembers Select SourceOne Where SourceOne.IsAssociation = False
  10:   
  11:          For Each SourceOne As Data.Linq.Mapping.MetaDataMember In SourceMembers
  12:              For Each TargetOne In targetEntity.GetType().GetFields()
  13:   
  14:                  If TargetOne.Name = SourceOne.Name Then
  15:                      Dim SourcePropInfo As System.Reflection.PropertyInfo = sourceEntity.[GetType]().GetProperty(SourceOne.Name)
  16:                      TargetOne.SetValue(targetEntity, SourcePropInfo.GetValue(sourceEntity, Nothing))
  17:                      Exit For
  18:                  End If
  19:   
  20:              Next
  21:          Next
  22:          Return targetEntity
  23:      End Function
  24:  End Module


And below you may see how to execute this function:




I hope you understanding how I transform nonserialized dynamically type that return Linq-to-SQL to statically type with the same name, that may be stored in Viewstate and names of this type is needed for control working.



Also in passing for this solution I avoided to rebuld big strange control. And my most important goal for this refactoring - I was be able to rebuild this fragment of site from untyped dataset to more useful Linq-to-SQL. All these goals I could get by creating this amazing Linq-to-SQL extension.





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