Re: No parameterless constructor error for dataview

[Hans Kesting]

on 23-9-2008, Julia B supposed :

Apologies for the cross posting. I posted to the datagrid group a couple of
weeks ago, but haven't got an answer so am trying here.
>

>
I'm trying to load some data into a dataview, with a datasource that is an
ObjectDataSourc e object and getting the message "No parameterless constructor
defined for this object". Basically the webform is in tier 1, which calls a
function called DisplayUsers in tier 2 (within the Users class), which in
turn calls a couple of functions/subs in tier 3. This is how it's set up.
>

Usually that errormessage means that you derived a class from a
baseclass that has no parameterless constructors.
Always when you call a constructor, a constructor of a baseclass is
also executed (before your own construcor executes). If you don't call
one explicitly, the parameterless constructor is called automatically.

I don't know what the VB syntax is. In C# it would be something like:

class MyClass: MyBaseClass
{
// MyBaseClass is a baseclass for this class and
// has a constructor with one 'int' parameter

// constructor that explicitly calls a constructor of the baseclass
public MyClass(int aValue): base(aValue)
{
// further processing as needed
}
}


Hans Kesting

[=?Utf-8?B?SnVsaWEgQg==?=]

Re: No parameterless constructor error for dataview

I don't think it's that. My class is not derived from a base class. Any other
ideas?

Thanks
Julia

"Hans Kesting" wrote:

on 23-9-2008, Julia B supposed :

Apologies for the cross posting. I posted to the datagrid group a couple of
weeks ago, but haven't got an answer so am trying here.

>

I'm trying to load some data into a dataview, with a datasource that is an
ObjectDataSourc e object and getting the message "No parameterless constructor
defined for this object". Basically the webform is in tier 1, which calls a
function called DisplayUsers in tier 2 (within the Users class), which in
turn calls a couple of functions/subs in tier 3. This is how it's set up.

>
Usually that errormessage means that you derived a class from a
baseclass that has no parameterless constructors.
Always when you call a constructor, a constructor of a baseclass is
also executed (before your own construcor executes). If you don't call
one explicitly, the parameterless constructor is called automatically.
>
I don't know what the VB syntax is. In C# it would be something like:
>
class MyClass: MyBaseClass
{
// MyBaseClass is a baseclass for this class and
// has a constructor with one 'int' parameter
>
// constructor that explicitly calls a constructor of the baseclass
public MyClass(int aValue): base(aValue)
{
// further processing as needed
}
}
>
>
Hans Kesting
>
>
>

[Hans Kesting]

Re: No parameterless constructor error for dataview

Julia B was thinking very hard :

I don't think it's that. My class is not derived from a base class. Any other
ideas?
>
Thanks
Julia
>

No specific ones, just general questions:
* When and where do you get that error exactly?
* Compile time/runtime?
* Source line
* Is there a stacktrace that can help you pinpoint the error?
* Can you shorten that example so that we don't have to wade through
all sorts of properties that are probably not involved in the problem?
If the system complains about a constructor, then SQL code is probably
not the problem.
See also http://www.yoda.arachsys.com/csharp/complete.html

Hans Kesting

"Hans Kesting" wrote:
>

>on 23-9-2008, Julia B supposed :

>>Apologies for the cross posting. I posted to the datagrid group a couple of
>>weeks ago, but haven't got an answer so am trying here.
>>>

>>

>>>
>>I'm trying to load some data into a dataview, with a datasource that is an
>>ObjectDataSou rce object and getting the message "No parameterless
>>constructor defined for this object". Basically the webform is in tier 1,
>>which calls a function called DisplayUsers in tier 2 (within the Users
>>class), which in turn calls a couple of functions/subs in tier 3. This is
>>how it's set up.
>>>

>>
>Usually that errormessage means that you derived a class from a
>baseclass that has no parameterless constructors.
>Always when you call a constructor, a constructor of a baseclass is
>also executed (before your own construcor executes). If you don't call
>one explicitly, the parameterless constructor is called automatically.
>>
>I don't know what the VB syntax is. In C# it would be something like:
>>
>class MyClass: MyBaseClass
>{
> // MyBaseClass is a baseclass for this class and
> // has a constructor with one 'int' parameter
>>
> // constructor that explicitly calls a constructor of the baseclass
> public MyClass(int aValue): base(aValue)
> {
> // further processing as needed
> }
>}
>>
>>
>Hans Kesting
>>
>>
>>