im wondering if this is possible or if someone has already created a mod for this..

how to have a field be auto-generated based off the calculation from other fields.

such as:

Labor: $
Parts: $
Tax: $ (parts * .06)
Total: (labor + parts + tax)

tax and total would be calculated from the input of parts and labor and stored in the database. tax and total would probably be hidded fields. i have some idea where to start on this, but wanted to see if anyone has attempted this same idea.

First, I would suggest that you define the tax rate in your .cfg file. Add a line somewhere --

$tax = .06;

If the tax rate changes, this makes it easier to remember where to make the change.

Is it really necessary to have the Tax and Total saved in a field on the record? Would it not be just as easy to compute it in html_record? The only reason I can see to have the fields is if you are using autogenerate.

If you are, the place to put these would be in add_record in db.cgi. Before the line that includes
&validate_record

add

$in{'Tax') = "\$" . ($in{'Parts'} * $tax);
$in{'Total'} = "\$" . ($in{'Labor'} + $in{'Parts'} + $in{'Tax'});

You would probably need to add the same thing to sub modify_record, in case there was a change in the Labor or Parts fields.



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JPD

Thanks. Much appreciated.

Since I am using auto-generate, how would i define Tax and Total in the .cfg?

Tax => [14, 'numer', -1, 10, 0, '', ''],
Total => [15, 'numer', -1, 10, 0, '', ''],

This didnt seem to do it, neither did making it visible (non-hidden).

Thanks again.

The calculation will only take place after you add the record. On the add form, the fields will be blank.

If you want them to show up when a record is displayed, you will have to set the field length to something greater than -1.


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JPD

I would recommend investing some time and using your own forms and turning off auto_generate.

In html_record_form you would only have a field for labour and parts, but when displaying a record you would calcualte the tax, and grand total and display that as well.

It would be more work to setup the forms, but would be a better solution in the long run..

Cheers,

Alex