Trouble with entities framework

ndmill1 · September 5th, 2011, 11:21 AM

I am trying to use the entities framework with my web site and can't get it to work with the GridView control. Here is the code in the code behind for the page including the GridView control:

Code:

Imports NDMDBModel

Partial Class Public_test
  Inherits System.Web.UI.Page

  Protected Sub Page_Load(sender As Object, e As System.EventArgs) Handles Me.Load
    Using myEntities As New NDMDBEntities()
      Dim allReviews = From CompanyNum In myEntities.CompanyNums
                       Order By CompanyNum.Company_num
                       Select CompanyNum
      GridView1.DataSource = allReviews
      GridView1.DataBind()
    End Using
  End Sub
End Class

the text "myEntities As New NDMDBEntities()" is underscored in blue and the text "allReviews" after the Dim statement is highlighted in green.

Any thoughts appreciated.

Imar · September 5th, 2011, 11:38 AM

Hi there,

Does the Error List provide more information that just the colors of the exceptions? ;-)

Cheers,

Imar

ndmill1 · September 6th, 2011, 07:50 AM

Sorry, I should have included them previously.

The error message related to the blue underscored

Code:

 myEntities As New NDMDBEntities()

is " 'Using' operand of type 'NDMDBModel.NDMDBEntities' must implement 'System.IDisposable' "

The green underscored

Code:

 Dim allReviews =

has an error message of "Variable declaration without an 'As' clause, type of object assumed"

My entities connection string also looks slightly different than the PlanetWrox example. It ends with

Code:

 multipleactiveresultsets=True;App=EntityFramework&quot;" providerName="System.Data.EntityClient" />

I appear to have some problem in the entities diagram with plurals. Although I have the box checked to use plurals in naming, I don't always get them. I think it is related to whether I declare a primary key with autonumbering. I am investigating that more.

Thanks for any inisghts you have.

Nelson Miller

Imar · September 6th, 2011, 02:03 PM

Hi there,

Sounds like your model isn't in order. Try this:

1. Comment out the code that results in the errors

2. Check your model and save all changes.

3. Right-click the Project in the Solution Explorer and choose Build or Rebuild.

4. Fix any errors listed in the Error List.

5. Try the code again.

For EF to work, your tables must have a primary key (e.g. at least one column needs the key icon in front of it). From an EF point of view, this doesn't have to be an identity. For the Planet Wrox web site the code assumes it's an identity though. You need to make these changes in the database before you create the EF model. If you make changes later you need to recreate or update the model.

Cheers,

Imar

ndmill1 · September 6th, 2011, 04:39 PM

Thanks for this Imar. Related question: some of my tables in SQL Server have names that include an underscore (example: Acttab_master). Any problem with this naming convention?

Regards,

Nelson

Imar · September 6th, 2011, 04:59 PM

Hi Nelson,

No, as far as I know you should be OK with an underscore. I don't like it personally, but that's a different topic.... ;-)

Did you manage to fix the problem?

Imar

ndmill1 · September 6th, 2011, 05:27 PM

Haven't tried it yet but will let you know.

Appreciate all your help.

ndmill1 · September 7th, 2011, 09:23 AM

Imar, deleted the edmx file and related connection string in the web.config file. Tried to recreate it and got 46 error messages (see below). Any quick thoughts? If not, I will try to work around by not using the entities framework approach.

Regards,

Nelson

1 Namespace or type specified in the Imports 'System.Data.Objects' doesn't contain any public member or cannot be found. Make sure the namespace or the type is defined and contains at least one public member. Make sure the imported element name doesn't use any aliases.
2 Namespace or type specified in the Imports 'System.Data.Objects.DataClasses' doesn't contain any public member or cannot be found. Make sure the namespace or the type is defined and contains at least one public member. Make sure the imported element name doesn't use any aliases.
3 Namespace or type specified in the Imports 'System.Data.EntityClient' doesn't contain any public member or cannot be found. Make sure the namespace or the type is defined and contains at least one public member. Make sure the imported element name doesn't use any aliases.
4 Type 'EdmSchemaAttribute' is not defined.
5 Type 'EdmRelationshipAttribute' is not defined.
6 Type 'ObjectContext' is not defined.
7 Type 'EntityConnection' is not defined.
8 Type 'ObjectSet' is not defined.
9 Type 'ObjectSet' is not defined.
10 Type 'ObjectSet' is not defined.
11 Type 'ObjectSet' is not defined.
12 Type 'EdmEntityTypeAttribute' is not defined.
13 Type 'EntityObject' is not defined.
14 Type 'EdmScalarPropertyAttribute' is not defined.
15 'ReportPropertyChanging' is not declared. It may be inaccessible due to its protection level.
16 'StructuralObject' is not declared. It may be inaccessible due to its protection level.
17 'ReportPropertyChanged' is not declared. It may be inaccessible due to its protection level.
18 Type 'EdmScalarPropertyAttribute' is not defined.
19 'ReportPropertyChanging' is not declared. It may be inaccessible due to its protection level.
20 'StructuralObject' is not declared. It may be inaccessible due to its protection level.
21 'ReportPropertyChanged' is not declared. It may be inaccessible due to its protection level.
22 Type 'EdmScalarPropertyAttribute' is not defined.
23 'ReportPropertyChanging' is not declared. It may be inaccessible due to its protection level.
24 'StructuralObject' is not declared. It may be inaccessible due to its protection level.
25 'ReportPropertyChanged' is not declared. It may be inaccessible due to its protection level.
26 Type 'EdmScalarPropertyAttribute' is not defined.
27 'ReportPropertyChanging' is not declared. It may be inaccessible due to its protection level.
28 'StructuralObject' is not declared. It may be inaccessible due to its protection level.
29 'ReportPropertyChanged' is not declared. It may be inaccessible due to its protection level.
30 Type 'EdmRelationshipNavigationPropertyAttribute' is not defined.
31 Type 'IEntityWithRelationships' is not defined.
32 Type 'IEntityWithRelationships' is not defined.
33 Type 'EntityReference' is not defined.
34 Type 'IEntityWithRelationships' is not defined.
35 Type 'IEntityWithRelationships' is not defined.
36 Type 'EdmEntityTypeAttribute' is not defined.
37 Type 'EntityObject' is not defined.
38 Type 'EdmScalarPropertyAttribute' is not defined.
39 'ReportPropertyChanging' is not declared. It may be inaccessible due to its protection level.
40 'StructuralObject' is not declared. It may be inaccessible due to its protection level.
41 'ReportPropertyChanged' is not declared. It may be inaccessible due to its protection level.
42 Type 'EdmScalarPropertyAttribute' is not defined.
43 'ReportPropertyChanging' is not declared. It may be inaccessible due to its protection level.
44 'StructuralObject' is not declared. It may be inaccessible due to its protection level.
45 'ReportPropertyChanged' is not declared. It may be inaccessible due to its protection level.
46 Type 'EdmRelationshipNavigationPropertyAttribute' is not defined.
47 Type 'EntityCollection' is not defined.
48 Type 'IEntityWithRelationships' is not defined.
49 Type 'IEntityWithRelationships' is not defined.

Imar · September 7th, 2011, 09:27 AM

A few questions to help figure out what's going on:

1. What's the physical folder of your web site on disk?

2. What's the name of the SQL Server database and where is it located on disk?

3. Where do you create this EDMX file? E.g. in which folder?

4. Is this a Web Site Project or a Web Application Project?

Imar

ndmill1 · September 7th, 2011, 10:16 AM

Imar,

1. What's the physical folder of your web site on disk?
C:\BegASPNET\ND_Miller

2. What's the name of the SQL Server database and where is it located on disk?
C:\BegASPNET\ND_Miller\App_Data\NDMDB.mdf

3. Where do you create this EDMX file? E.g. in which folder?
C:\BegASPNET\ND_Miller\App_Code

4. Is this a Web Site Project or a Web Application Project?
I believe it is a project - On opening VWD it refers to the file as a project. Other than that I am not sure how to confirm. I think I followed the instructions in the book to work with project and not applications

P.S. - I realize you can't spend unlimited time on this so don't hesitate to redirect me if appropriate.

Regards,

Nelson