Validator handler uses a Python expression in validating a value in the parent attribute. The handler evaluates the expression and displays an error if the expression returns a false value.

For information about Python, please visit www.python.org. A quick tutorial on Python can be found at www.python.org/doc/tut. Efecte uses a Python implementation called Jython. Jython specific documentation is available at www.jython.org.

Validator handler validates the value only when the data is created or edited through the user interface: a normal data card edit or by multiediting (multiedit since 4.1 4113). Note: When multi editing data cards, the validation may fail because other fields of the data card doesn't match the validation and preventing saving the data card. A check will not be performed if the source data is imported to Matrix42.

The data is considered valid if expression or script result is one of the following:

• Empty string ('' or "").
• A number other than zero (0). Jython uses 1 instead of boolean value True.
• Successful regular expression match.

Note the following error cases:

• A non-empty string is interpreted as an error message.
• 0 is invalid. That may be result of a boolean expression.
• None is invalid. An unsuccessful regular expression match returns None.

You can use the Validator handler, for example, to compare the values of different attributes denoted by their individual attribute codes in the parent attribute's metadata.

Parent attribute value can be referred using the variable moniker _current.

For example, to ensure, that the parent attribute Amount is larger than Q2, attach the Validator handler to the attribute Amount and denote the following Python Validator in the metadata expression: _current>[attributeCodeQ2] . When saving, Validator handler evaluates the expression and returns an error to the user if the condition is not met.

The following tables provide information on the attribute settings and metadata requirements for Validator handler. Compulsory metadata is provided in a Required attribute metadata table.

Configuration of Validator handler varies from other handlers. Needed metadata names are given, admin must give the values only.

Table 1. Attribute Settings

Table 2. Required Attribute Metadata

Table 3. Optional Attribute Metadata

Validator handler also allows access to referenced data cards. The current card can be referred with this, and other data cards by their the class attribute code configured in the parent card. Currently supported methods for referred data cards are:

Table 4. Data Card Access Methods

Script Examples

Ensure that current attribute value is between 50 and 100:

50<_current<100

Check that the length of the current field is exactly 8

len(_current)==8

Lets assume: 1) "car" is a single value reference of _this_ template 2) "limit" an integer attribute of _car_ template 3) Check that current attribute value is less than the limit from single car reference

_current<car.get("car_limit")

Decide the error message based on the current attribute and attribute with the code speed_limit. Requires isScript option:

if _current>speed_limit:
  _result='The value must be smaller than the speed limit!'
elif _current<0:
  _result='The value must be larger than zero!'

Check that the current field matches a given regular expression, where the input must be of form EFECTE-nnnnnn, where n is a number:

re.match(r"EFECTE-\d{6}",_current)

Check that the current field matches a given regular expression, where the input must start with an letter A and a number:

re.match(r"A\d.*",_current)

If the jobstate attribute has value Closed and the travel_time or actual_work_time attribute is empty, display an error message.

errorText = ""
if (this.get("jobstate")=="Closed" and this.get("travel_time")==None):
   errorText=errorText + "<br/>Please fill in the 'Travel time' field"
if (this.get("jobstate")=="Closed" and this.get("actual_work_time")==None):
   errorText=errorText + "<br/>Please fill in the 'Actual work time' field"
if (errorText != "" ):
   _result=errorText