Verifies that a record complies with mandatory
field and unique index definitions.
Syntax
VALIDATE record [ NO-ERROR ]
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-
record
-
The name of the record you want to validate.
To validate
a record in a table defined for multiple databases, you must qualify
the record's table name with the database name. See the Record phrase reference
entry for more information.
- NO-ERROR
-
Suppresses ABL errors or error messages that would otherwise occur
and diverts them to the ERROR-STATUS system handle. If an error occurs, the action of the statement
is not done and execution continues with the next statement. If
the statement fails, any persistent side-effects of the statement
are backed out. If the statement includes an expression that contains
other executable elements, like methods, the work performed by these
elements may or may not be done, depending on the order the AVM
resolves the expression elements and the occurrence of the error.
To
check for errors after a statement that uses the NO-ERROR option:
- Check the ERROR-STATUS:ERROR attribute to see if the AVM raised
the ERROR condition.
- Check if the ERROR-STATUS:NUM-MESSAGES attribute is greater than
zero to see if the AVM generated error messages. ABL handle methods
used in a block without a CATCH end block treat errors as
warnings and do not raise ERROR, do not set the ERROR-STATUS:ERROR
attribute, but do add messages to the ERROR-STATUS system handle.
Therefore, this test is the better test for code using handle methods
without CATCH end blocks. ABL handle methods used in a block with a
CATCH end block raise ERROR and add messages to the error object
generated by the AVM. In this case, the AVM does not update the
ERROR-STATUS system handle.
- Use ERROR-STATUS:GET-MESSAGE( message-num )
to retrieve a particular message, where message-num is
1 for the first message.
If the statement does not include
the NO-ERROR option, you can use a CATCH end block to handle errors
raised by the statement.
Some other important usage notes
on the NO-ERROR option:
- NO-ERROR does not suppress errors
that raise the STOP or QUIT condition.
- A CATCH statement, which introduces a CATCH end block, is analogous
to a NO-ERROR option in that it also suppresses errors, but it does so
for an entire block of code. It is different in that the error messages
are contained in a class-based error object (generated by the AVM
or explicitly thrown), as opposed to the ERROR-STATUS system handle.
Also, if errors raised in the block are not handled by a compatible
CATCH block, ON ERROR phrase, or UNDO statement, then the error
is not suppressed, but handled with the default error processing
for that block type.
- When a statement contains the NO-ERROR option and resides in
a block with a CATCH end block, the NO-ERROR option takes precedence over
the CATCH block. That is, an error raised on the statement with
the NO-ERROR option will not be handled by a compatible CATCH end block.
The error is redirected to the ERROR-STATUS system handle as normal.
- If an error object is thrown to a statement that includes the NO-ERROR
option, then the information and messages in the error object will
be used to set the ERROR-STATUS system handle. This interoperability
feature is important for those integrating code that uses the traditional
NO-ERROR technique with the newer, structured error handling that
features error objects and CATCH end blocks.
Example
This
procedure prompts for an item number. If an Item with that number is
not available, the procedure creates a new Item record and lets
you supply some Item information. The VALIDATE statement checks
the data you enter against the index and mandatory field criteria
for the Item record.
r-valid.p
REPEAT FOR Item:
PROMPT-FOR Item.ItemNum.
FIND Item USING Item.ItemNum NO-ERROR.
IF NOT AVAILABLE Item THEN DO:
CREATE iIem.
ASSIGN Item.ItemNum.
UPDATE Item.ItemName Item.Price.
VALIDATE Item.
END.
ELSE
DISPLAY Item.ItemName Item.Price.
END.
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Notes
- Because
validation is done automatically, you rarely have to use the VALIDATE
statement. The AVM automatically validates a record when a record
in the record buffer is replaced by another, a record's scope iterates
or ends, the innermost iterating subtransaction block that creates a
record iterates, or a transaction ends.
- The AVM automatically validates mandatory fields when those fields
are modified.
- If the validation fails on a newly-created record, VALIDATE
raises the ERROR condition.
- The AVM performs validation when it leaves a field.
- For complex validations, it might be easier to use the IF...THEN...ELSE
statement instead of the VALIDATE statement.
- You cannot use the VALIDATE statement to test fields that are
referenced in SQL statements, since validation is not performed
for these fields.
- If a field or table has been modified, the VALIDATE statement
causes WRITE events and all related WRITE triggers to execute.