How to trap "Index or primary key canot contain a null value"

[p0welly]

I have a form with a data sheet that allows information to be keyed into a table, this table has a primary key that must be filled in. if you dont, you get the error message "Index or primary key cannon contain a null value"

How can I trap this error and replace the message with something more friendly?

Ive tried the on error event but this just displays my message before the access one

 

[Kodo]

How about a field valdation before the record gets saved?
If FIELD ="" then
'show message
'set focus back to field
End IF

?
Your user should never be able to get to save the record if required items are not filled in.

 

[p0welly]

Excellent Thanks for pointing me in the right direction, I ended up with the following on the before update.

if isnull(category) then
Msgbox "you must enter a category"
mycancelbuttonpressed = true
else
mycancelbuttonpressed = false
end if

if mycancelbuttonpressed = true then
cancel = true
exit sub
end if

the mycancelbuttonpressed bit was also found on here

 

[ghudson]

What if the field contains an empty string? User starts to key something then they remove it... It is now empty but no longer null.

If IsNull(txtCategory) or txtCategory = "" Then

 

[EMP]

What if the field contains an empty string? User starts to key something then they remove it... It is now empty but no longer null.

If a user starts to key something then they remove it... It is now null.

It is a zero-length string only if the user specifically keyed "".

^