Call the methods and catch the exceptions – PB Docs 2019

Call the
methods and catch the exceptions

Where you are

Add a new sheet window
to the existing application

Create a new user
function and user event

> Call the methods
and catch the exceptions

You now write code to populate the drop-down list box controls with
state codes from the customer table in the Demo Database database. Since
you made the control editable, an application user can also type in a
value for the state code. Before you process a user-entered value, you
check to make sure the value conforms to the conditions you set in the
ue_modified event, namely that it is two characters in length.

You also add code to the Clicked event of the command button control
to process the current state code in the drop-down list box control. In
the Clicked event you call the uf_percentage function to calculate the
percentage of customers from the selected state and catch all exceptions
that can be thrown by the function.

Make sure the w_cust_pct is open in the Window painter and that
ddlb_state displays in the first drop-down list box of the Script
view.
Select losefocus ( ) returns long [pbm_cbnkillfocus] in the
second drop-down list box.

Call the ue_modified event and catch the exception object that
it throws by entering the following lines for the losefocus event
script:

Try 
      this.EVENT ue_modified(this.text)
Catch (exc_bad_entry le_be)
      messagebox ("from exc_bad_entry", &amp;             
         le_be.getmessage())
End Try

return 1

Try

this.EVENT ue_modified(this.text)

Catch (exc_bad_entry le_be)

messagebox ("from exc_bad_entry", &

le_be.getmessage())

End Try

return 1

Select constructor ( ) returns long [pbm_constructor] from the
second drop-down list box in the Script view prototype window for the
ddlb_state control.

Enter the following lines in the Constructor event to populate
the drop-down list box control:

int       li_nrows, n
string       ls_state

//Get the distinct count of all states in the 
//customer table
SELECT count(distinct state) INTO :li_nrows 
FROM customer;

//Declare the SQL cursor to select all states
//in customer table but avoid
//rows with duplicate values for state.
DECLARE custstatecursor CURSOR FOR 
SELECT state FROM customer
GROUP BY state HAVING count(state)=1
UNION 
SELECT state FROM customer
GROUP BY state
HAVING count(state)&gt;1;
OPEN custstatecursor ;
//Populate the control with a single entry for
//every state in the customer table.
FOR n=1 TO li_nrows
      FETCH NEXT custstatecursor INTO :ls_state;            
      this.additem( ls_state)
NEXT
CLOSE custstatecursor ;
//Set first item in list as selected item
this.selectitem (1)

int li_nrows, n

string ls_state

//Get the distinct count of all states in the

//customer table

SELECT count(distinct state) INTO :li_nrows

FROM customer;

//Declare the SQL cursor to select all states

//in customer table but avoid

//rows with duplicate values for state.

DECLARE custstatecursor CURSOR FOR

SELECT state FROM customer

GROUP BY state HAVING count(state)=1

UNION

SELECT state FROM customer

GROUP BY state

HAVING count(state)>1;

OPEN custstatecursor ;

//Populate the control with a single entry for

//every state in the customer table.

FOR n=1 TO li_nrows

FETCH NEXT custstatecursor INTO :ls_state;

this.additem( ls_state)

CLOSE custstatecursor ;

//Set first item in list as selected item

this.selectitem (1)

Select cb_percent from the first drop-down list in the Script
view.

Make sure clicked ( ) returns long [pbm_bnclicked] displays in
the second drop-down list box.

Enter the following lines for the Clicked event script:

Decimal my_result 
Double entry_1, entry_2
Int li_int, li_rtn
String sel_state

sel_state=ddlb_state.text
//Get the number of rows with customers from the 
//selected states and place in the entry_1 variable.
//Change the first static control to display this
//number.

SELECT count(*) INTO :entry_1 FROM customer
      WHERE customer.state=:sel_state;
st_1.text="Customers in state: " + string(entry_1)

//Get the total number of customers and place in 
//the entry_2 variable.
//Change the second static control to display this 
//number.
SELECT count(*) INTO :entry_2 FROM customer;
st_2.text="Total number of customers: " &amp;
      + string(entry_2)

//Call uf_percentage and catch its exceptions.
TRY 
      my_result = uf_percentage (entry_1, entry_2)
CATCH (exc_no_rows e_nr )
      MessageBox("From exc_no_rows",       &amp;
         e_nr.getmessage())
CATCH (exc_low_number e_ln )
      li_int=1 
      MessageBox("From exc_low_number", &amp;             
         e_ln.getmessage())
   CATCH (dividebyzeroerror e_zero)
      li_rtn = MessageBox("No Customers", &amp;
         "Terminate Application?", Stopsign!, YesNo!)
      IF li_rtn=1 THEN
         HALT
      END IF
END TRY

//Display the message in the text box. Vary the //message depending on whether there is only one 
//customer for the selected state or if more than 
//one customer resides in selected state.
IF li_int=1 THEN
      sle_result.text ="Value not calculated for " &amp; 
         + sel_state + "."    + " Try another state."
ELSE
      sle_result.text = String (my_result) + &amp;
         " % of customers are in " + sel_state + "."
END IF

Decimal my_result

Double entry_1, entry_2

Int li_int, li_rtn

String sel_state

sel_state=ddlb_state.text

//Get the number of rows with customers from the

//selected states and place in the entry_1 variable.

//Change the first static control to display this

//number.

SELECT count(*) INTO :entry_1 FROM customer

WHERE customer.state=:sel_state;

st_1.text="Customers in state: " + string(entry_1)

//Get the total number of customers and place in

//the entry_2 variable.

//Change the second static control to display this

//number.

SELECT count(*) INTO :entry_2 FROM customer;

st_2.text="Total number of customers: " &

+ string(entry_2)

//Call uf_percentage and catch its exceptions.

TRY

my_result = uf_percentage (entry_1, entry_2)

CATCH (exc_no_rows e_nr )

MessageBox("From exc_no_rows", &

e_nr.getmessage())

CATCH (exc_low_number e_ln )

li_int=1

MessageBox("From exc_low_number", &

e_ln.getmessage())

CATCH (dividebyzeroerror e_zero)

li_rtn = MessageBox("No Customers", &

"Terminate Application?", Stopsign!, YesNo!)

IF li_rtn=1 THEN

HALT

END IF

END TRY

//Display the message in the text box. Vary the //message depending on whether there is only one

//customer for the selected state or if more than

//one customer resides in selected state.

IF li_int=1 THEN

sle_result.text ="Value not calculated for " &

+ sel_state + "." + " Try another state."

ELSE

sle_result.text = String (my_result) + &

" % of customers are in " + sel_state + "."

END IF

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Powerbuilder Documentation 2019

August 21, 2023

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Call the methods and catch the exceptions – PB Docs 2019

Call the
methods and catch the exceptions

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