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NullReferenceException when using DAAB

Posted on 2006-05-01
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Last Modified: 2012-08-13
Hello,
  I'm using Data Access Application Block (MS Enterprise Library). I installed it and configured my app.config file as per the instructions using the "Enterprise Library Configuration" tool. Here is what my app.config looks like:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
    <section name="dataConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Data.Configuration.DatabaseSettings, Microsoft.Practices.EnterpriseLibrary.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null" />
  </configSections>
 
  <connectionStrings>
    <add name="MyDB"
         connectionString="Database=TestDB;Server=(local)\SQLEXPRESS;Integrated Security=SSPI;User Instance=true;"
      providerName="System.Data.SqlClient" />
  </connectionStrings>
  <dataConfiguration defaultDatabase="MyDB" />
</configuration>

Here is a call that I'm making:

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.Practices.EnterpriseLibrary.Data;
using Microsoft.Practices.EnterpriseLibrary.Data.Sql;
using System.Data.Common;
using System.Data;
using System.Configuration;


            Database db = DatabaseFactory.CreateDatabase();

However, I get a NullReferenceException on this line but the exception shows up in the "DatabaseConfigurationView.cs" file in DefaultName:

public string DefaultName
{
      get
            {
                  DatabaseSettings settings = this.DatabaseSettings;
Throws excpetion-->            string databaseName = settings.DefaultDatabase;                        
                  return databaseName;
            }
}

I would appreciate any help on this. I'm learning to use DAAB for the first time so not sure what I'm doing wrong here.

thanks,

Rahul
0
Comment
Question by:rahulInSD
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6 Comments
 
LVL 35

Expert Comment

by:mrichmon
ID: 16578710
Try

Database db = DatabaseFactory.CreateDatabase("MyDB");

Then it should read the connection string out of the config file.
0
 

Author Comment

by:rahulInSD
ID: 16585254
hi,
 Thanks for the tip but I did that as well and I get the following exception:"ConfigurationErrorException was unhandled" in the same file with this message:

"The requested database MyDB is not defined in configuration."

Any ideas what I'm doing wrong in the configuration???

Rahul
0
 

Author Comment

by:rahulInSD
ID: 16585333
Problem solved....Actually the problem was related to how I had setup my solution. I had a ClassLibrary project which I am calling DAL (short for Data Access Layer). This DAL.dll was using the DAAB and I had use the enterprise library configuration tool to create its configuration file DAL.dll.config.

However I was using this DAL.dll in another Windows Forms Application and I did not have anything defined in the windows application's config file. So when I was running the code, it was looking for the config section of the windows applicaiton not the DAL.dll.config.

so to fix it all I had to do was copy the contents from the DAL.dll.config to Windows Form Application's config file. I could have used the Enterprise Library Configuration also and pointed it to my Windows Form Application to configure it.

Rahul
0
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LVL 35

Expert Comment

by:mrichmon
ID: 16586783
Glad you got it working.
0
 
LVL 35

Expert Comment

by:mrichmon
ID: 16817617
I would PAQ/Refund this.
0
 

Accepted Solution

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ID: 16968203
PAQed with points refunded (125)

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