Test if child records exist

#1

Hi,

I have Form1 with a pushButton that opens Form2 containing a tableFrame. I
want the pushButton's color and label to be dependant on whether Form1's
current record has any child records in Form2's tableFrame. I'm guessing I
need to put code into Form1's arriveEvent... but I don't know what code to
use to test an unopened table for child records based on Form1's current
record.

Could someone please help me?

Thanx for your time... Frank

#2

Frank

Use a Tcursor to inspect the underlying table. You can then change the
properties as needed

Chuck

#3

Actually I think you will need to put it in the new value or change value of
the key field on form 1 since you will want to know if there are child records
not just for the first record in the table but for each as you scroll. Using a
tc all you will have to do is setrange the tc and test for Nrecords = 0.

Denn Santoro
President
Resource Development Associates
http://www.RDAWorldWide.Com
Offices in the United States and Germany
Providing solutions to health care, business, governments and non-profits since
1982

#4

Hi Chuck,

Thanx for the reply.

I'm novice level with this OPal stuff.

I figured I needed a TCursor. It's the code for "the test" I'm stumped on.

Right now I'm just trying to get the button to change color. It hasn't yet.

The following is located in the active form's, key field, changeValue.event:
;================================
method changeValue(var eventInfo ValueEvent)

var
locationsTC TCursor
currentRec anyType
endVar

;|| assign current rec's field.value to variable
currentRec = appID.value

;|| open locationsTC
if not locationsTC.open(":fcc:iLocation.db") then
errorShow("Could not open the iLocation.db table")
return
endIf

;|| setRange based on current record
locationsTC.setRange(currentRec,currentRec)

;|| color button dependant on if child recs exist
if locationsTC.Nrecords() <> 0 then
pButLocations.color = "red"
else
pButLocations.color = "gray"
endIf

;|| close locationsTC
if not locationsTC.close() then
errorShow("Could not close iLocation.db table")
return
endIf

endMethod
;================================

Am I getting close?

THANX for your time... Frank

"Chuck Folkes(sbc)" <Cfolkes (AT) sbcglobal (DOT) net> wrote

Quote:

Frank

Use a Tcursor to inspect the underlying table. You can then change the
properties as needed

Chuck

#5

Hi Dennis,

Thanx for the reply.

I'm novice level with this OPal stuff.

I figured I needed a TCursor. It's the code for "the test" I'm stumped on.

Right now I'm just trying to get the button to change color. It hasn't yet.

The following is located in the active form's, key field, changeValue.event:
;================================
method changeValue(var eventInfo ValueEvent)

var
locationsTC TCursor
currentRec anyType
endVar

;|| assign current rec's field.value to variable
currentRec = appID.value

;|| open locationsTC
if not locationsTC.open(":fcc:iLocation.db") then
errorShow("Could not open the iLocation.db table")
return
endIf

;|| setRange based on current record
locationsTC.setRange(currentRec,currentRec)

;|| color button dependant on if child recs exist
if locationsTC.Nrecords() <> 0 then
pButLocations.color = "red"
else
pButLocations.color = "gray"
endIf

;|| close locationsTC
if not locationsTC.close() then
errorShow("Could not close iLocation.db table")
return
endIf

endMethod
;================================

Am I getting close?

THANX for your time... Frank

"Dennis Santoro" <RDAPres (AT) NoRDASpamWorldWide (DOT) com> wrote

Quote:

Actually I think you will need to put it in the new value or change value
of
the key field on form 1 since you will want to know if there are child
records
not just for the first record in the table but for each as you scroll.
Using a
tc all you will have to do is setrange the tc and test for Nrecords = 0.

Denn Santoro
President
Resource Development Associates
http://www.RDAWorldWide.Com
Offices in the United States and Germany
Providing solutions to health care, business, governments and non-profits
since
1982

#6

Pretty close. Try it in the new value and see what happens when you scroll. Also
be sure the fields are contained in a record object, not just bare fields on a
form. Also, you don't need the range to have the value twice for a single value
setrange. A single value on the key is treated as exact match. Not sure why you
are using an anytype for the key value. Try using the same type as the field
(hopefully long int). Finally, get in the habit of using a naming convention
that makes very clear what all your variables are by type. See the faq on naming
conventions for a good one.

Also, if you are just a beginner here I'd suggest you check out my Database
Basics paper to help learn some best practices and common pitfalls. You can get
it on our Paradox resources page (link in my signature)

Denn Santoro
President
Resource Development Associates
http://www.RDAWorldWide.Com
Offices in the United States and Germany
Providing solutions to health care, business, governments and non-profits since
1982

#7

Quote:

Right now I'm just trying to get the button to change color. It hasn't yet.

I don't think you can change the color of a standard paradox
pushbutton. You can change the text and text object color.

If you want button color, try placing a box object on the button and
change its color.

Randy

#8

Good point. Should have caught that in my earlier reply.

Denn Santoro
President
Resource Development Associates
http://www.RDAWorldWide.Com
Offices in the United States and Germany
Providing solutions to health care, business, governments and non-profits since
1982

#9

Hi Dennis,

Sorry for the delayed response.

Quote:

Try it in the new value and see what happens when you scroll

<<
Tried it... pButLocations.color won't change

Quote:

Also be sure the fields are contained in a record object, not just bare

fields on a form
<<
I hope I'm understanding you correctly. I'm assuming "the fields" you are
speaking of... is the "one" field... with the changeValue(or newValue) code
attached to it (and not the fields in the table that the tCursor is
attached to). If that's the case then... no can do. The appID.field (the
primary key field for the main table attached to Form1) has to sit "bare" on
Form1 to accomodate all the other required fields needed for data entry. A
table object would require a horizontal scroll bar a mile long.

Quote:

Also, you don't need the range to have the value twice for a single value

setrange. A single value on the key is treated as exact match.
<<
Done

Quote:

Not sure why you are using an anytype for the key value. Try using the same

type as the field (hopefully long int).
<<
smallInt... done

Quote:

Finally, get in the habit of using a naming convention that makes very clear

what all your variables are by type. See the faq on naming conventions for a
good one.
<<
THANX... I checked it out.

Quote:

Also, if you are just a beginner here I'd suggest you check out my Database

Basics paper to help learn some best practices and common pitfalls. You can
get it on our Paradox resources page (link in my signature)
<<
Coooooool doc. Basically, I do follow most all your suggestions. Always
generated my own keys (never have used the autoExcrement field type since I
accomodate creating keys over a network) but, over the years, I have wimpped
out on a few of my table disciplines (a couple use PDox's Ref Integrity, a
couple have 10-12 character filenanmes). Other than that it's getting my
naming conventions in shape. Since I have no desire to write for others I
really don't need portability strategies.

So... here's where I'm at. The button still doesn't change color. Code is
attached to the appID.field sitting "bare" on Form1

==========================
method newValue(var eventInfo Event)

var
tcLocations tCursor
siCurrentRec smallInt
endVar

;|| assign current rec's field.value to variable
siCurrentRec = appID.value

;|| open tcLocations
if not tcLocations.open(":fcc:iLocation.db") then
errorShow("Could not open the iLocation.db table")
return
endIf

;|| setRange based on current record
tcLocations.setRange(siCurrentRec)

;|| color button dependant on if child recs exist
if tcLocations.Nrecords() <> 0 then
pButLocations.color = red
else
pButLocations.color = gray
endIf

;|| close tcLocations
if not tcLocations.close() then
errorShow("Could not close iLocation.db table")
return
endIf

endMethod
==========================

THANX again for your time... Frank

"Dennis Santoro" <RDAPres (AT) NoRDASpamWorldWide (DOT) com> wrote

Quote:

Pretty close. Try it in the new value and see what happens when you
scroll. Also
be sure the fields are contained in a record object, not just bare fields
on a
form. Also, you don't need the range to have the value twice for a single
value
setrange. A single value on the key is treated as exact match. Not sure
why you
are using an anytype for the key value. Try using the same type as the
field
(hopefully long int). Finally, get in the habit of using a naming
convention
that makes very clear what all your variables are by type. See the faq on
naming
conventions for a good one.

Also, if you are just a beginner here I'd suggest you check out my
Database
Basics paper to help learn some best practices and common pitfalls. You
can get
it on our Paradox resources page (link in my signature)

Denn Santoro
President
Resource Development Associates
http://www.RDAWorldWide.Com
Offices in the United States and Germany
Providing solutions to health care, business, governments and non-profits
since
1982

#10

Frank,

See below.

Frank Cutre wrote:

Quote:

Hi Dennis,

Sorry for the delayed response.

Try it in the new value and see what happens when you scroll

Tried it... pButLocations.color won't change

Did you see the other response? YOu can't change a button's color. Get something
else in there to try the test. Change the color of the text, change the color of
a box. Pop up a message. Etc.

Quote:

Also be sure the fields are contained in a record object, not just bare
fields on a form

I hope I'm understanding you correctly. I'm assuming "the fields" you are
speaking of... is the "one" field... with the changeValue(or newValue) code
attached to it (and not the fields in the table that the tCursor is
attached to).

Right. The ones the tc are attached to are not on display. Tcs are memory
constructs.

Quote:

If that's the case then... no can do. The appID.field (the
primary key field for the main table attached to Form1) has to sit "bare" on
Form1 to accomodate all the other required fields needed for data entry. A
table object would require a horizontal scroll bar a mile long.

Then you have a real problem. You either have a terrible normalization or you
need to learn about MROs or both. See my papers on Contanership on forms and
Normalization on our paradox resources page (Link in my signature). If you have
not read the Database basics paper yet read that to You almost always want
fields that are bound to tables contained in a record object (tableframe or MRO)
as otherwise you are missing a lot of basic behaviors. There has been much
discussion on this in the groups you can find and it is discussed in the papers
I mentioned. Botton line, it CAN be done and SHOULD be.

Quote:

Also, you don't need the range to have the value twice for a single value
setrange. A single value on the key is treated as exact match.

Done

Not sure why you are using an anytype for the key value. Try using the same
type as the field (hopefully long int).

smallInt... done

Finally, get in the habit of using a naming convention that makes very clear
what all your variables are by type. See the faq on naming conventions for a
good one.

THANX... I checked it out.

Also, if you are just a beginner here I'd suggest you check out my Database
Basics paper to help learn some best practices and common pitfalls. You can
get it on our Paradox resources page (link in my signature)

Coooooool doc. Basically, I do follow most all your suggestions. Always
generated my own keys (never have used the autoExcrement field type since I
accomodate creating keys over a network) but, over the years, I have wimpped
out on a few of my table disciplines (a couple use PDox's Ref Integrity, a
couple have 10-12 character filenanmes). Other than that it's getting my
naming conventions in shape. Since I have no desire to write for others I
really don't need portability strategies.

So... here's where I'm at. The button still doesn't change color. Code is
attached to the appID.field sitting "bare" on Form1

==========================
method newValue(var eventInfo Event)

var
tcLocations tCursor
siCurrentRec smallInt
endVar

;|| assign current rec's field.value to variable
siCurrentRec = appID.value

;|| open tcLocations
if not tcLocations.open(":fcc:iLocation.db") then
errorShow("Could not open the iLocation.db table")
return
endIf

;|| setRange based on current record
tcLocations.setRange(siCurrentRec)

Try testing this (if not...etc.)

Quote:

;|| color button dependant on if child recs exist
if tcLocations.Nrecords() <> 0 then
pButLocations.color = red
else
pButLocations.color = gray
endIf

Again, buttons are grey. Test the code with some other indicator.

Denn Santoro
President
Resource Development Associates
http://www.RDAWorldWide.Com
Offices in the United States and Germany
Providing solutions to health care, business, governments and non-profits since
1982