Calculating a label value in the detail band

rbuser

Hi,

in the detail band i have a label which holds the values of three fields
from the database (they are obviously converted to string and concatenated
together). Is it possible to calulate the value of the label only once
(let's say at the report's first pass) and not every time the label is
displayed? I'm asking this because in the label's OnPrint event i have an
sql query which executes (to get the three values) and it's a little time
consuming. On the other hand, if i don't execute it every time the label is
displayed, the label has the same value across the whole report (i had a
similar problem in a previous post i made, and i used a TppVariable which
executed at every traversal...not very optimal).

Thanx for any suggestions

nicocizik

Hi jure,

In the Report.OnStartPage, you could check to see if Report.FirstPass is
true and if it is, make your calculations. This is definitely a good way to
optimize what your report is printing.

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rbuser

to

Hi Nico,

so you are saying that there is no need to refresh the label each time it's
displayed. If i do so, the label has the same caption across the whole
report (probbably the value of the last record that was printed).

Or did you mean something else in your comment and i didn't understand
right?

nicocizik

I'm sorry, I forgot to say to also check that the Report.AbsolutePageNo = 1,
so that it will only fire once and you will have no repeats.

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rbuser

1,

Sorry, but i think we misunderstod. You say that it's possible to
print/calculate the labels only during the report's first pass. Then the
user can navigate through pages and there is no need to refresh the label
when it's printed again, if i understood well. But, as i said, if i don't
refresh the label each time it prints (in the label's OnPrint event) the
label has the same value in the whole report. Example:

Correctly displayed report:

ID ProblematicLabel
1 A
2 B
3 C
4 D
5 E


Erroneously displayed report:

ID ProblematicLabel
1 E
2 E
3 E
4 E
5 E

If i wasn't clear enough, please tell me.

Thanx

nicocizik

Hi,

Ok, I think I understand what is going on. Since the TppLabel.OnPrint event
fires numerous times during generation, you will need to keep track of the
current ID (which you already have) and the previous ID (from the last time
you entered this event). Each time you enter this event, check to see if
the two values are the same. If they are not, update the previous ID to the
current one and update the TppLabel component. If they are the same, do
nothing and keep generating. This should get you going in the right
direction.

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