How: replace "type in field" with calculated field without disturbing existing data

[Karsten]

I my Alpha 5 V11 I have 1 "type in field" which I would like to replace with a calculated field to automatically set the per day cost depending on day of arrival date. The calculated field is easy to create and a subsequent field easy to change, bur unfortunately it changes the data in the field and depended fields all the way back to day 1. Is there any way to stop this (Freeze all data before a certain date) either by creating a range or some other means. And if there is how to implement it.

[Ted Giles]

Re: How: replace "type in field" with calculated field without disturbing existing data

Try setting a Default value for the field.

[Stan Mathews]

Re: How: replace "type in field" with calculated field without disturbing existing data

To expand a bit on Ted's suggestion.

Set the field rule to Data Entry, Default Mode to Simple Default Expression.
Make the expression your current calculation.
Set the Skip expression to .T.

Image 3.png

Upon testing it seems advisable to also check the box for,

At end of enter, set........

[natn1251]

Re: How: replace "type in field" with calculated field without disturbing existing data

Hello Karstein

Another solution is to use a variable instead of calculated field. On the form set a variable using the form drop down menu in design mode. set the equals to 1 this makes it Numeric automatically. Next in the on fetch event of the form add code simular to this

if record_date < Date New Process Starts than
     myform:myvar.value = myform:myfield.value
else
     myform:myvar.value = mycalculation
end if
parentform.refresh_layout()

record_date is a value stored in the existing records which will be used as a branch in the code
Date New process starts is a date or some value which tells the system when to display the new value
myform is the name of your form
myvar is the name of the variable you will create
myfield is the field you are changing

move the field to an empty spot on the form and go to the object properties and check hide
even though hidden, the field value is fetched each time you fetch a new record.
if you want to store the calculated value then when a record past the change date is fetched you could have
the on fetch event assign the calculated value to the myfield.value

mycalculation is the calculation you created

This process works very fast.

Hope this helps