Hi,

I've just hit a very unusual situation within my application where it is
raising an access violation.

I have the following code:

function TDmCommonChecks.GetNameIDFromABBCode(ABBCode : String): String;
var
 s : String;
begin
if not assigned(DMCommonChecks) then
 Application.CreateForm(TDMCommonChecks, DMCommonChecks);
 result := '';
 DMCommonChecks.CustomQ.close;
 DMCommonChecks.customQ.sql.clear;
 s := 'Select ID from Names where (ABBCD  =  '+Quotedstr(ABBCode)+')';
 DMCommonChecks.customQ.sql.add(s); //<<<<<<<<<<<<<<<<<<<<AV
 DMCommonChecks.CustomQ.open;
......

I'm getting an access violation here whenever I try to add to the SQL
property. I can use SQL.CLEAR, but I can't use SQL.ADD, nor SQL.LOADFROMFILE

It doesn't seem to matter what string I try to add in there, it AV's
every time.

This has got me quite confused, considering that everything up to this
point behaves correctly.

Does anyone know what might be causing a problem trying to assign a
string to the SQL property?

Thanks & Regards

Adam.

To add to the confusion, this particular unit is part of another
application. (Shared unit). It works fine in the original application,
but it's not working properly in my new application.


> Hi,
>
> I've just hit a very unusual situation within my application where it is
> raising an access violation.
>
> I have the following code:
>
> function TDmCommonChecks.GetNameIDFromABBCode(ABBCode : String): String;
> var
>   s : String;
> begin
> if not assigned(DMCommonChecks) then
>   Application.CreateForm(TDMCommonChecks, DMCommonChecks);
>   result := '';
>   DMCommonChecks.CustomQ.close;
>   DMCommonChecks.customQ.sql.clear;
>   s := 'Select ID from Names where (ABBCD  =  '+Quotedstr(ABBCode)+')';
>   DMCommonChecks.customQ.sql.add(s); //<<<<<<<<<<<<<<<<<<<<AV
>   DMCommonChecks.CustomQ.open;
> .....
>
> I'm getting an access violation here whenever I try to add to the SQL
> property. I can use SQL.CLEAR, but I can't use SQL.ADD, nor
> SQL.LOADFROMFILE
>
> It doesn't seem to matter what string I try to add in there, it AV's
> every time.
>
> This has got me quite confused, considering that everything up to this
> point behaves correctly.
>
> Does anyone know what might be causing a problem trying to assign a
> string to the SQL property?
>
> Thanks & Regards
>
> Adam.

Nevermind... it appears as though it's not DBISam at all - because other
'shared' forms are also experiencing the same problem with TStrings
(such as memo objects)...

The weirdness continues. :-/

On 27/07/2012 11:20 AM, Adam H. wrote:
> To add to the confusion, this particular unit is part of another
> application. (Shared unit). It works fine in the original application,
> but it's not working properly in my new application.
>
>
>> Hi,
>>
>> I've just hit a very unusual situation within my application where it is
>> raising an access violation.
>>
>> I have the following code:
>>
>> function TDmCommonChecks.GetNameIDFromABBCode(ABBCode : String): String;
>> var
>>   s : String;
>> begin
>> if not assigned(DMCommonChecks) then
>>   Application.CreateForm(TDMCommonChecks, DMCommonChecks);
>>   result := '';
>>   DMCommonChecks.CustomQ.close;
>>   DMCommonChecks.customQ.sql.clear;
>>   s := 'Select ID from Names where (ABBCD  =  '+Quotedstr(ABBCode)+')';
>>   DMCommonChecks.customQ.sql.add(s); //<<<<<<<<<<<<<<<<<<<<AV
>>   DMCommonChecks.CustomQ.open;
>> .....
>>
>> I'm getting an access violation here whenever I try to add to the SQL
>> property. I can use SQL.CLEAR, but I can't use SQL.ADD, nor
>> SQL.LOADFROMFILE
>>
>> It doesn't seem to matter what string I try to add in there, it AV's
>> every time.
>>
>> This has got me quite confused, considering that everything up to this
>> point behaves correctly.
>>
>> Does anyone know what might be causing a problem trying to assign a
>> string to the SQL property?
>>
>> Thanks & Regards
>>
>> Adam.
>

Just a suggestion but why are you using  CreateForm?!

why not just  DMCommonChecks := TDMCommonChecks.Create ?


Raul



On 7/26/2012 9:05 PM, Adam H. wrote:
> Hi,
>
> I've just hit a very unusual situation within my application where it is
> raising an access violation.
>
> I have the following code:
>
> function TDmCommonChecks.GetNameIDFromABBCode(ABBCode : String): String;
> var
>   s : String;
> begin
> if not assigned(DMCommonChecks) then
>   Application.CreateForm(TDMCommonChecks, DMCommonChecks);
>   result := '';
>   DMCommonChecks.CustomQ.close;
>   DMCommonChecks.customQ.sql.clear;
>   s := 'Select ID from Names where (ABBCD  =  '+Quotedstr(ABBCode)+')';
>   DMCommonChecks.customQ.sql.add(s); //<<<<<<<<<<<<<<<<<<<<AV
>   DMCommonChecks.CustomQ.open;
> .....
>
> I'm getting an access violation here whenever I try to add to the SQL
> property. I can use SQL.CLEAR, but I can't use SQL.ADD, nor
> SQL.LOADFROMFILE
>
> It doesn't seem to matter what string I try to add in there, it AV's
> every time.
>
> This has got me quite confused, considering that everything up to this
> point behaves correctly.
>
> Does anyone know what might be causing a problem trying to assign a
> string to the SQL property?
>
> Thanks & Regards
>
> Adam.

Good Morning Raul,

Good question. It's something I've been using for the last decade -
probably something I learned (incorrectly?) and have stuck with.

Is there much difference between the two?

Cheers

Adam.

> Just a suggestion but why are you using  CreateForm?!
>
> why not just  DMCommonChecks := TDMCommonChecks.Create ?
>
>
> Raul
>
>
>
> On 7/26/2012 9:05 PM, Adam H. wrote:
>> Hi,
>>
>> I've just hit a very unusual situation within my application where it is
>> raising an access violation.
>>
>> I have the following code:
>>
>> function TDmCommonChecks.GetNameIDFromABBCode(ABBCode : String): String;
>> var
>>   s : String;
>> begin
>> if not assigned(DMCommonChecks) then
>>   Application.CreateForm(TDMCommonChecks, DMCommonChecks);
>>   result := '';
>>   DMCommonChecks.CustomQ.close;
>>   DMCommonChecks.customQ.sql.clear;
>>   s := 'Select ID from Names where (ABBCD  =  '+Quotedstr(ABBCode)+')';
>>   DMCommonChecks.customQ.sql.add(s); //<<<<<<<<<<<<<<<<<<<<AV
>>   DMCommonChecks.CustomQ.open;
>> .....
>>
>> I'm getting an access violation here whenever I try to add to the SQL
>> property. I can use SQL.CLEAR, but I can't use SQL.ADD, nor
>> SQL.LOADFROMFILE
>>
>> It doesn't seem to matter what string I try to add in there, it AV's
>> every time.
>>
>> This has got me quite confused, considering that everything up to this
>> point behaves correctly.
>>
>> Does anyone know what might be causing a problem trying to assign a
>> string to the SQL property?
>>
>> Thanks & Regards
>>
>> Adam.
>

Adam,

There is definitely nothing wrong with it - IDE uses it. There are some
small limitations - 1st form created becomes the app main window and
application is the owner of the form.

However what you described (TStrings not getting created) looks like a
init issue so i always try to simplify things to narrow it down is all.

Either you init routines are not running properly (inherited not called
somewhere?) or otherwise smething is freeing the form variables.

Raul

On 7/29/2012 7:14 PM, Adam H. wrote:
> Good Morning Raul,
>
> Good question. It's something I've been using for the last decade -
> probably something I learned (incorrectly?) and have stuck with.
>
> Is there much difference between the two?
>
> Cheers
>
> Adam.
>
>> Just a suggestion but why are you using  CreateForm?!
>>
>> why not just  DMCommonChecks := TDMCommonChecks.Create ?
>>
>>
>> Raul

Adam,

This function is confusing me... When are you calling it, from where?
You are creating the form inside a function that is a method of the form you are creating...


--
Fernando Dias
[Team Elevate]

Hi Raul,

The problem ended up being involved with an inherited form.  They were
two separate units and forms. I'm not sure exactly where, but when I
copied the original ancestor form to the new project, it behaved fine!

Thanks for your help!

Cheers

Adam.

> Adam,
>
> There is definitely nothing wrong with it - IDE uses it. There are some
> small limitations - 1st form created becomes the app main window and
> application is the owner of the form.
>
> However what you described (TStrings not getting created) looks like a
> init issue so i always try to simplify things to narrow it down is all.
>
> Either you init routines are not running properly (inherited not called
> somewhere?) or otherwise smething is freeing the form variables.
>
> Raul
>
> On 7/29/2012 7:14 PM, Adam H. wrote:
>> Good Morning Raul,
>>
>> Good question. It's something I've been using for the last decade -
>> probably something I learned (incorrectly?) and have stuck with.
>>
>> Is there much difference between the two?
>>
>> Cheers
>>
>> Adam.
>>
>>> Just a suggestion but why are you using  CreateForm?!
>>>
>>> why not just  DMCommonChecks := TDMCommonChecks.Create ?
>>>
>>>
>>> Raul
>

Hi Fernando,

Correct. It's effectively a function that uses a code to return a GUID
field.

This function is used all over the project in many areas. So I only need
to call the function once, without creating code to create and destroy
the form in every unit that calls the function (Could be 40 or more
different units), I've placed it all in the one area.

I could have two separate units I suppose - one where the code is
outside the form that contains the query / components - but this seems
to be working fine, and simplifies things. (Everything is in the one
location).

HTH

Adam.

On 31/07/2012 4:08 AM, Fernando Dias wrote:
> Adam,
>
> This function is confusing me... When are you calling it, from where?
> You are creating the form inside a function that is a method of the form
> you are creating...
>
>
> --
> Fernando Dias
> [Team Elevate]

Adam,

Ah, it's declared as a class method, right?

Fernando Dias
[Team Elevate]