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order of execution of page_load in a base and derived classes

 
 
Ignacio Machin \( .NET/ C# MVP \)
Guest
Posts: n/a
 
      09-01-2004
Hi,

I have never been in this situation, but the first thing I would try is in
the Form.OnInit move the base.OnInit to the start of the method, before
register the Load handler for the current page.



cheers,

--
Ignacio Machin,
ignacio.machin AT dot.state.fl.us
Florida Department Of Transportation



"z. f." <> wrote in message
news:%...
> Hi,
>
> i have a class that is derived from System.Web.UI.Page, and this is the
> class i use in my application as PageBase.
> all other page classes are deriverd from my PageBase instead of the

original
> System.Web.UI.Page in order to have common checks in the page base.
>
> i make securirty checks in the page base page_load event.
> if the security fails, i can do whatever i want before the "real" /

derived
> page gets to be executed.
>
> but i have noticed that the derived page load event gets to be called

before
> the base page load event.
>
> so i have a problem.
>
> i can cancel the use of page_load in my derived pages, but i use this
> function to check on PostBack events that does not have server (like

button)
> event handler, but there when will i move it to?
>
> is this the correct execution order - the derived gets to called before

the
> base?
>
> is this also the order of execution in inheritence or only with delegated
> event handlers? ( i mean when you use the syntax of Page.onLoad +=
> this_onLoad )....
>
> TIA, z.
>
>



 
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Karl
Guest
Posts: n/a
 
      09-01-2004
Please don't cross-post.

I'm assuming you are using C# 'cuz you wouldn't have this behaviour in
VB....anyways, the simplest solution is to go into your derived page's
OnInit function in the "Web Form Designer generated code" region, and change
the order of the two executions:

InitializeComponent();
base.OnInit(e);

to

base.OnInit(e);
InitializeComponent();

This will cause the base page's init to load first, which will cause it's
Load event to get hooked up first, thus causing it to fire first.

Karl

"z. f." <> wrote in message
news:%...
> Hi,
>
> i have a class that is derived from System.Web.UI.Page, and this is the
> class i use in my application as PageBase.
> all other page classes are deriverd from my PageBase instead of the

original
> System.Web.UI.Page in order to have common checks in the page base.
>
> i make securirty checks in the page base page_load event.
> if the security fails, i can do whatever i want before the "real" /

derived
> page gets to be executed.
>
> but i have noticed that the derived page load event gets to be called

before
> the base page load event.
>
> so i have a problem.
>
> i can cancel the use of page_load in my derived pages, but i use this
> function to check on PostBack events that does not have server (like

button)
> event handler, but there when will i move it to?
>
> is this the correct execution order - the derived gets to called before

the
> base?
>
> is this also the order of execution in inheritence or only with delegated
> event handlers? ( i mean when you use the syntax of Page.onLoad +=
> this_onLoad )....
>
> TIA, z.
>
>



 
Reply With Quote
 
 
 
 
Ignacio Machin \( .NET/ C# MVP \)
Guest
Posts: n/a
 
      09-01-2004
Hi again

I'm not very sure that the previous answer will solve the problem, IIRC
the order of execution of the handlers is not defined. therefore even ify ou
register first the parent you may get the derived executing first after all.

Therefore you have to use another approach, you could use a virtual method
that you call in the OnLoad event, so each class Page) define what needs to
be checked , being the trick to verify the parent first to have the first
line calling the parent method:
protected override Check()
{
parent.Check();
//do the checking
}

I think this will solve your problem.


Cheers,

--
Ignacio Machin,
ignacio.machin AT dot.state.fl.us
Florida Department Of Transportation





"z. f." <> wrote in message
news:%...
> Hi,
>
> i have a class that is derived from System.Web.UI.Page, and this is the
> class i use in my application as PageBase.
> all other page classes are deriverd from my PageBase instead of the

original
> System.Web.UI.Page in order to have common checks in the page base.
>
> i make securirty checks in the page base page_load event.
> if the security fails, i can do whatever i want before the "real" /

derived
> page gets to be executed.
>
> but i have noticed that the derived page load event gets to be called

before
> the base page load event.
>
> so i have a problem.
>
> i can cancel the use of page_load in my derived pages, but i use this
> function to check on PostBack events that does not have server (like

button)
> event handler, but there when will i move it to?
>
> is this the correct execution order - the derived gets to called before

the
> base?
>
> is this also the order of execution in inheritence or only with delegated
> event handlers? ( i mean when you use the syntax of Page.onLoad +=
> this_onLoad )....
>
> TIA, z.
>
>



 
Reply With Quote
 
Benjamin Schwitter
Guest
Posts: n/a
 
      09-01-2004
We had the same problem with the Page_Load Event.

We solved it similar to the way Ignacio Machin describes using the OnLoad
event.

Good luck,

Benjamin Schwitter

"Ignacio Machin ( .NET/ C# MVP )" <ignacio.machin AT dot.state.fl.us> wrote
in message news:#...
> Hi again
>
> I'm not very sure that the previous answer will solve the problem, IIRC
> the order of execution of the handlers is not defined. therefore even ify

ou
> register first the parent you may get the derived executing first after

all.
>
> Therefore you have to use another approach, you could use a virtual

method
> that you call in the OnLoad event, so each class Page) define what needs

to
> be checked , being the trick to verify the parent first to have the first
> line calling the parent method:
> protected override Check()
> {
> parent.Check();
> //do the checking
> }
>
> I think this will solve your problem.
>
>
> Cheers,
>
> --
> Ignacio Machin,
> ignacio.machin AT dot.state.fl.us
> Florida Department Of Transportation
>
>
>
>
>
> "z. f." <> wrote in message
> news:%...
> > Hi,
> >
> > i have a class that is derived from System.Web.UI.Page, and this is the
> > class i use in my application as PageBase.
> > all other page classes are deriverd from my PageBase instead of the

> original
> > System.Web.UI.Page in order to have common checks in the page base.
> >
> > i make securirty checks in the page base page_load event.
> > if the security fails, i can do whatever i want before the "real" /

> derived
> > page gets to be executed.
> >
> > but i have noticed that the derived page load event gets to be called

> before
> > the base page load event.
> >
> > so i have a problem.
> >
> > i can cancel the use of page_load in my derived pages, but i use this
> > function to check on PostBack events that does not have server (like

> button)
> > event handler, but there when will i move it to?
> >
> > is this the correct execution order - the derived gets to called before

> the
> > base?
> >
> > is this also the order of execution in inheritence or only with

delegated
> > event handlers? ( i mean when you use the syntax of Page.onLoad +=
> > this_onLoad )....
> >
> > TIA, z.
> >
> >

>
>



 
Reply With Quote
 
z. f.
Guest
Posts: n/a
 
      09-01-2004
Hi,

i have a class that is derived from System.Web.UI.Page, and this is the
class i use in my application as PageBase.
all other page classes are deriverd from my PageBase instead of the original
System.Web.UI.Page in order to have common checks in the page base.

i make securirty checks in the page base page_load event.
if the security fails, i can do whatever i want before the "real" / derived
page gets to be executed.

but i have noticed that the derived page load event gets to be called before
the base page load event.

so i have a problem.

i can cancel the use of page_load in my derived pages, but i use this
function to check on PostBack events that does not have server (like button)
event handler, but there when will i move it to?

is this the correct execution order - the derived gets to called before the
base?

is this also the order of execution in inheritence or only with delegated
event handlers? ( i mean when you use the syntax of Page.onLoad +=
this_onLoad )....

TIA, z.


 
Reply With Quote
 
z. f.
Guest
Posts: n/a
 
      09-01-2004
i use vb.net
and i don't override the OnInit method in my PageBase.



"Karl" <karl REMOVE @ REMOVE openmymind REMOVEMETOO . ANDME net> wrote in
message news:...
> Please don't cross-post.
>
> I'm assuming you are using C# 'cuz you wouldn't have this behaviour in
> VB....anyways, the simplest solution is to go into your derived page's
> OnInit function in the "Web Form Designer generated code" region, and

change
> the order of the two executions:
>
> InitializeComponent();
> base.OnInit(e);
>
> to
>
> base.OnInit(e);
> InitializeComponent();
>
> This will cause the base page's init to load first, which will cause it's
> Load event to get hooked up first, thus causing it to fire first.
>
> Karl
>
> "z. f." <> wrote in message
> news:%...
> > Hi,
> >
> > i have a class that is derived from System.Web.UI.Page, and this is the
> > class i use in my application as PageBase.
> > all other page classes are deriverd from my PageBase instead of the

> original
> > System.Web.UI.Page in order to have common checks in the page base.
> >
> > i make securirty checks in the page base page_load event.
> > if the security fails, i can do whatever i want before the "real" /

> derived
> > page gets to be executed.
> >
> > but i have noticed that the derived page load event gets to be called

> before
> > the base page load event.
> >
> > so i have a problem.
> >
> > i can cancel the use of page_load in my derived pages, but i use this
> > function to check on PostBack events that does not have server (like

> button)
> > event handler, but there when will i move it to?
> >
> > is this the correct execution order - the derived gets to called before

> the
> > base?
> >
> > is this also the order of execution in inheritence or only with

delegated
> > event handlers? ( i mean when you use the syntax of Page.onLoad +=
> > this_onLoad )....
> >
> > TIA, z.
> >
> >

>
>



 
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z. f.
Guest
Posts: n/a
 
      09-01-2004
i wouldn't like to add code to each page-class i add.
the idea behind using a PageBase is to not change the way i write the other
pages, just let them use the services the PageBase implement without even
"knowing" anout it.


"Ignacio Machin ( .NET/ C# MVP )" <ignacio.machin AT dot.state.fl.us> wrote
in message news:%...
> Hi again
>
> I'm not very sure that the previous answer will solve the problem, IIRC
> the order of execution of the handlers is not defined. therefore even ify

ou
> register first the parent you may get the derived executing first after

all.
>
> Therefore you have to use another approach, you could use a virtual

method
> that you call in the OnLoad event, so each class Page) define what needs

to
> be checked , being the trick to verify the parent first to have the first
> line calling the parent method:
> protected override Check()
> {
> parent.Check();
> //do the checking
> }
>
> I think this will solve your problem.
>
>
> Cheers,
>
> --
> Ignacio Machin,
> ignacio.machin AT dot.state.fl.us
> Florida Department Of Transportation
>
>
>
>
>
> "z. f." <> wrote in message
> news:%...
> > Hi,
> >
> > i have a class that is derived from System.Web.UI.Page, and this is the
> > class i use in my application as PageBase.
> > all other page classes are deriverd from my PageBase instead of the

> original
> > System.Web.UI.Page in order to have common checks in the page base.
> >
> > i make securirty checks in the page base page_load event.
> > if the security fails, i can do whatever i want before the "real" /

> derived
> > page gets to be executed.
> >
> > but i have noticed that the derived page load event gets to be called

> before
> > the base page load event.
> >
> > so i have a problem.
> >
> > i can cancel the use of page_load in my derived pages, but i use this
> > function to check on PostBack events that does not have server (like

> button)
> > event handler, but there when will i move it to?
> >
> > is this the correct execution order - the derived gets to called before

> the
> > base?
> >
> > is this also the order of execution in inheritence or only with

delegated
> > event handlers? ( i mean when you use the syntax of Page.onLoad +=
> > this_onLoad )....
> >
> > TIA, z.
> >
> >

>
>



 
Reply With Quote
 
Karl
Guest
Posts: n/a
 
      09-01-2004
Can you show me some code? If I do this:

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
Trace.Write("derived load")
end sub

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
Trace.Write("baseload")
end sub

the base load always fires first.

Karl

"z. f." <> wrote in message
news:%...
> i use vb.net
> and i don't override the OnInit method in my PageBase.
>
>
>
> "Karl" <karl REMOVE @ REMOVE openmymind REMOVEMETOO . ANDME net> wrote in
> message news:...
> > Please don't cross-post.
> >
> > I'm assuming you are using C# 'cuz you wouldn't have this behaviour in
> > VB....anyways, the simplest solution is to go into your derived page's
> > OnInit function in the "Web Form Designer generated code" region, and

> change
> > the order of the two executions:
> >
> > InitializeComponent();
> > base.OnInit(e);
> >
> > to
> >
> > base.OnInit(e);
> > InitializeComponent();
> >
> > This will cause the base page's init to load first, which will cause

it's
> > Load event to get hooked up first, thus causing it to fire first.
> >
> > Karl
> >
> > "z. f." <> wrote in message
> > news:%...
> > > Hi,
> > >
> > > i have a class that is derived from System.Web.UI.Page, and this is

the
> > > class i use in my application as PageBase.
> > > all other page classes are deriverd from my PageBase instead of the

> > original
> > > System.Web.UI.Page in order to have common checks in the page base.
> > >
> > > i make securirty checks in the page base page_load event.
> > > if the security fails, i can do whatever i want before the "real" /

> > derived
> > > page gets to be executed.
> > >
> > > but i have noticed that the derived page load event gets to be called

> > before
> > > the base page load event.
> > >
> > > so i have a problem.
> > >
> > > i can cancel the use of page_load in my derived pages, but i use this
> > > function to check on PostBack events that does not have server (like

> > button)
> > > event handler, but there when will i move it to?
> > >
> > > is this the correct execution order - the derived gets to called

before
> > the
> > > base?
> > >
> > > is this also the order of execution in inheritence or only with

> delegated
> > > event handlers? ( i mean when you use the syntax of Page.onLoad +=
> > > this_onLoad )....
> > >
> > > TIA, z.
> > >
> > >

> >
> >

>
>



 
Reply With Quote
 
z. f.
Guest
Posts: n/a
 
      09-01-2004
also

from the IL created by VB compiler you see that in the constructor it is
adding the event handler:

Public Sub New()
AddHandler MyBase.Load, New EventHandler(AddressOf Me.Page_Load)
End Sub





"Karl" <karl REMOVE @ REMOVE openmymind REMOVEMETOO . ANDME net> wrote in
message news:...
> Please don't cross-post.
>
> I'm assuming you are using C# 'cuz you wouldn't have this behaviour in
> VB....anyways, the simplest solution is to go into your derived page's
> OnInit function in the "Web Form Designer generated code" region, and

change
> the order of the two executions:
>
> InitializeComponent();
> base.OnInit(e);
>
> to
>
> base.OnInit(e);
> InitializeComponent();
>
> This will cause the base page's init to load first, which will cause it's
> Load event to get hooked up first, thus causing it to fire first.
>
> Karl
>
> "z. f." <> wrote in message
> news:%...
> > Hi,
> >
> > i have a class that is derived from System.Web.UI.Page, and this is the
> > class i use in my application as PageBase.
> > all other page classes are deriverd from my PageBase instead of the

> original
> > System.Web.UI.Page in order to have common checks in the page base.
> >
> > i make securirty checks in the page base page_load event.
> > if the security fails, i can do whatever i want before the "real" /

> derived
> > page gets to be executed.
> >
> > but i have noticed that the derived page load event gets to be called

> before
> > the base page load event.
> >
> > so i have a problem.
> >
> > i can cancel the use of page_load in my derived pages, but i use this
> > function to check on PostBack events that does not have server (like

> button)
> > event handler, but there when will i move it to?
> >
> > is this the correct execution order - the derived gets to called before

> the
> > base?
> >
> > is this also the order of execution in inheritence or only with

delegated
> > event handlers? ( i mean when you use the syntax of Page.onLoad +=
> > this_onLoad )....
> >
> > TIA, z.
> >
> >

>
>



 
Reply With Quote
 
Ignacio Machin \( .NET/ C# MVP \)
Guest
Posts: n/a
 
      09-01-2004
Hi,

IIRC the Page_Load is added in the OnInit handler:

override protected void OnInit(EventArgs e)
{
InitializeComponent();
base.OnInit(e);
}
private void InitializeComponent()
{
this.Load += new System.EventHandler(this.Page_Load);
}



Cheers,

--
Ignacio Machin,
ignacio.machin AT dot.state.fl.us
Florida Department Of Transportation

"z. f." <> wrote in message
news:...
> also
>
> from the IL created by VB compiler you see that in the constructor it is
> adding the event handler:
>
> Public Sub New()
> AddHandler MyBase.Load, New EventHandler(AddressOf Me.Page_Load)
> End Sub
>
>
>
>
>
> "Karl" <karl REMOVE @ REMOVE openmymind REMOVEMETOO . ANDME net> wrote in
> message news:...
> > Please don't cross-post.
> >
> > I'm assuming you are using C# 'cuz you wouldn't have this behaviour in
> > VB....anyways, the simplest solution is to go into your derived page's
> > OnInit function in the "Web Form Designer generated code" region, and

> change
> > the order of the two executions:
> >
> > InitializeComponent();
> > base.OnInit(e);
> >
> > to
> >
> > base.OnInit(e);
> > InitializeComponent();
> >
> > This will cause the base page's init to load first, which will cause

it's
> > Load event to get hooked up first, thus causing it to fire first.
> >
> > Karl
> >
> > "z. f." <> wrote in message
> > news:%...
> > > Hi,
> > >
> > > i have a class that is derived from System.Web.UI.Page, and this is

the
> > > class i use in my application as PageBase.
> > > all other page classes are deriverd from my PageBase instead of the

> > original
> > > System.Web.UI.Page in order to have common checks in the page base.
> > >
> > > i make securirty checks in the page base page_load event.
> > > if the security fails, i can do whatever i want before the "real" /

> > derived
> > > page gets to be executed.
> > >
> > > but i have noticed that the derived page load event gets to be called

> > before
> > > the base page load event.
> > >
> > > so i have a problem.
> > >
> > > i can cancel the use of page_load in my derived pages, but i use this
> > > function to check on PostBack events that does not have server (like

> > button)
> > > event handler, but there when will i move it to?
> > >
> > > is this the correct execution order - the derived gets to called

before
> > the
> > > base?
> > >
> > > is this also the order of execution in inheritence or only with

> delegated
> > > event handlers? ( i mean when you use the syntax of Page.onLoad +=
> > > this_onLoad )....
> > >
> > > TIA, z.
> > >
> > >

> >
> >

>
>



 
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