By debugging my test application
described before. I found out, that the scenario can be simplified as
follows:
Create an ASP.NET project
Add an SqlDataSource to Default.aspxSet the ConnectionString property
to a valid network connection via an ODBC database driver
Do not define the SelectCommand
property
In Page_Load enter the following
code: DataView
dv=(DataView)SqlDataSource1.Select(DataSourceSelectArguments.Empty);
The
application displays the infamous error page starting with
„ExecuteReader:
CommandText is not set.“ under Mono 2.10.5.
Under .Net is simply displays an empty page. The Select() method
returns null in this case.
What
we can conclude from this, is that the root cause of the problem is
actually located somewhere inside SqlDataSource and it's dependencies
and not part of the DataBound controls.
I
think SqlDataSourceView.ExecuteSelect() would be a good place to
check for the SelectCommand property. If it's empty the method should
simply return null.
From: [email protected]
To: [email protected]
Date: Fri, 16 Sep 2011 13:44:30 +0000
Subject: Re: [Mono-aspnet-list] GridView/ Databinding bug in Mono 2.10.5
By inspecting/ debugging the class library I think there might be a problem in
DataBoundControl.OnPagePreLoad() which calls DataBoundControl.Initialize(). The
comment in the code says
that the DataBoundControl.RequiresDataBinding property should be set to true in
cases where the HTTP request is not a postback or it is a postback and view
state is enabled but the data-bound control has not yet been bound. This is
wrong because it does not consider the SelectCommand property of the
SqlDataSource. If this property has not been defined, data binding must not
take place.
From: [email protected]
To: [email protected]
Date: Fri, 16 Sep 2011 13:34:37 +0000
Subject: [Mono-aspnet-list] GridView/ Databinding bug in Mono 2.10.5
Databinding in Mono is different
compared to .Net Framework. I have observed this within a complex web
application. Below you will find the steps to create a small example
web app that demonstrates the issue:
Create an ASP.NET project
Add a GridView to Default.aspx
Add an SqlDataSource to
Default.aspx and connect it to the GridView
Set the ConnectionString property
to a valid network connection via an ODBC database driver
Do not define the SelectCommand
property
Add an event handler
SqlDataSource1_Selecting() which should be called whenever a
databindung operation ocurrs.
Put a breakpoint in
SqlDataSource1_Selecting() to verify if databinding takes place
If you run the application in Visual
Studio, you will notice that SqlDataSource1_Selecting() is never
called. But if you run the application in Mono 2.10.5
SqlDataSource1_Selecting() is called which will result in an
exception because the SelectCommand property is actually not defined.
It is common practice not to define the
SelectCommand property within the .aspx file but rather calulate the
actual query string within the code behind. Defineing the
SelectCommand property within the .aspx file requires the use of ODBC
parameters. However, Mono does currently not support this (see bug
#694047 -> reported 4 months ago but not resolved yet). As a result we are
forced to use the code behind method in
Mono if we need to access a database via ODBC.
Best regards,Martin
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