Subsonic 3.0.0.4 ActiveRecord Template for MySQL error on inserting new record

Question

public void Add(IDataProvider provider){


    var key=KeyValue();
    if(key==null){
        var newKey=_repo.Add(this,provider);
        this.SetKeyValue(newKey);
    }else{
        _repo.Add(this,provider); //NullReferenceException was unhandled by user code
    }
    SetIsNew(false);
    OnSaved();
}

'this' contains

this
{Geocine}
    _age: null
    _birthday: null
    _church_id: null
    _db: {Seminary.Data.SeminaryDB}
    _dirtyColumns: Count = 0
    _finalgrade: null
    _finalgrade_equivalent: null
    _first_name: "Geocine"
    _gender: null
    _isLoaded: false
    _isNew: true
    _last_name: "Cruz"
    _level: null
    _middle_name: "Reilly"
    _repo: {SubSonic.Repository.SubSonicRepository<Seminary.Data.student>}
    _semester_enrolled: null
    _seminary_id: null
    _student_id: 0
    _year_enrolled: null
    age: null
    birthday: null
    church_id: null
    Columns: Count = 14
    finalgrade: null
    finalgrade_equivalent: null
    first_name: "Geocine"
    gender: null
    last_name: "Cruz"
    level: null
    middle_name: "Reilly"
    semester_enrolled: null
    seminary_id: null
    student_id: 0
    tbl: {student}
    TestMode: false
    year_enrolled: null

provider contains

provider
{SubSonic.DataProviders.DbDataProvider}
    [SubSonic.DataProviders.DbDataProvider]: {SubSonic.DataProviders.DbDataProvider}
    Client: MySqlClient
    ConnectionString: "Data Source=localhost;Database=school;User Id=root;Password=123456;Port=3306;"
    CurrentSharedConnection: null
    DbDataProviderName: "MySql.Data.MySqlClient"
    Factory: {MySql.Data.MySqlClient.MySqlClientFactory}
    Log: null
    Name: "MySql.Data.MySqlClient"
    ParameterPrefix: "@"
    Schema: {SubSonic.Schema.DatabaseSchema}
    SchemaGenerator: {SubSonic.SqlGeneration.Schema.MySqlSchema}

Here is the stacktrace

[NullReferenceException: Object reference not set to an instance of an object.]
   MySql.Data.MySqlClient.MySqlConnection.get_ServerThread() +6
   MySql.Data.MySqlClient.MySqlConnection.Abort() +54
   MySql.Data.MySqlClient.MySqlCommand.ExecuteReader(CommandBehavior behavior) +839
   MySql.Data.MySqlClient.MySqlCommand.ExecuteDbDataReader(CommandBehavior behavior) +4
   System.Data.Common.DbCommand.ExecuteReader(CommandBehavior behavior) +10
   SubSonic.DataProviders.DbDataProvider.ExecuteReader(QueryCommand qry) +175
   SubSonic.Repository.SubSonicRepository`1.Add(T item, IDataProvider provider) +165
   Seminary.Data.student.Add(IDataProvider provider) in C:\Users\SomeUser\Documents\Visual Studio 2008\Projects\Seminary\ActiveRecord\ActiveRecord.cs:2490
   Seminary.Data.student.Save(IDataProvider provider) in C:\Users\SomeUser\Documents\Visual Studio 2008\Projects\Seminary\ActiveRecord\ActiveRecord.cs:2505
   Seminary.Data.student.Save() in C:\Users\SomeUser\Documents\Visual Studio 2008\Projects\Seminary\ActiveRecord\ActiveRecord.cs:2499
   Seminary.Default.btnAdd_Click(Object sender, EventArgs e) in C:\Users\SomeUser\Documents\Visual Studio 2008\Projects\Seminary\Default.aspx.cs:34
   System.Web.UI.WebControls.Button.OnClick(EventArgs e) +111
   System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +110
   System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1565

Here is the code that called the error:

    student studentObject = new student();
    studentObject.first_name = txtFirstName.Text;
    studentObject.middle_name = txtMiddleName.Text;
    studentObject.last_name = txtLastName.Text;
    studentObject.Save();

Answer 1

That is a bit tricky. This exceptions happens with the current version of mysql.connector.net.

Normally an exception would be trown at this point, but the connector seems to have an NullReferenceException itself before it can throw the actual exception.

The "real" exception could be anything from "DUPLICATE KEY ..." to "Field XYZ does not have a default value" or "You have an error in your SQL Syntax near ..."

I haven't had time yet to figure out why this happens (debug the Connector.Net or try a newer one) but in the mean time I would suggest you do the following as I do:

Download unix tools for windows: http://unxutils.sourceforge.net/ and put them in the path (we need the tail command) Configure mysql to write a query.log to c:\temp

[mysqld]
log=c:/temp/query.log

Start a console and type

tail -f c:\temp\query.log

Now you see every statement that is executed against your local database and if you get the NullReferenceException copy the last statement form the console window to a mysql query browser instance and execute it there.

Hope that helps, I will update this post if I figured out how to fix this issue.