Python Value Ranges

• The following Python methods can be defined in the attribute Wertebereich of all Dataitems.
  • They are used to calculate or process the value of a Dataitem.
• You can use the full spectrum of methods available in the Python-API.

List of Functions

Note:

• PLANTA Server tries to convert the return values of the functions computeOutput() and processInput() to the underlying DI's type.
• When that fails, it issues a message box containing a Python error similar to the following one:

Python error in value range of DI041035 "di_customizing_name": computeOutput

<class 'TypeError'>:
  argument must be string, not None

Note:

• Setting datafield or dataitem values using the Python API will never trigger the checkInput() function of a Python value range, while processInput() will be evaluated.

Information

• The checkInput() function is evaluated before processInput() is called.
• Thus checkInput() will inhibit calling processInput() when it does not accept the input.
• computeOutput() is evaluated whenever the DI's value is read. No evaluation might happen when PLANTA Server is in echo off mode (using ppms.echo_off() or ppms.echo_disabled()), as PLANTA Server refreshes the DI-values during the serialization step (which is skipped in echo off mode).

Dependency Tracking

• Since it is impossible to "auto-detect" all the possible source data references of the respective function, it is necessary to specify them.
  • Every function has an dependency attribute, deps which contains a tuple of DI source data references. PLANTA then can assure that all references are available when ever this DI is calculated.
• Special feature of the computeOutput() function:
  • The function is called whenever a source reference changes, this means that the result of the computeOutput() function is always up to date according to its source references.

Details

• Following functions must have dependencies:
  • computeOutput()
  • processInput()
  • checkInput()
• The tuple of dependencies can contain
  • DI references (DIs from the same record): ‘DI000123'
  • Variable references (@G, @D, @L, @M): ‘@G15','@L1'
  • '*' meaning that the value has to be recalculated in any case. This will have bad influence on the performance,therefor use this feature with caution.
• It is not necessary to add the DI containing the value range to the dependencies.
  • Example: when the computeOutput() is customized on DI123456 it's not necessary to add DI123456 to the dependencies.
• If the DI only interacts with itself, simply add deps = ('',)
• If there's only one DI in the dependency add deps = ('DI012345',)

The tuple is specified in the source code of the python value range like this:

import random
def computeOutput(di):
   list = ppms.uvar_get('@M6')
   return random.choice(list)
computeOutput.deps = ('@M6',) 

• In this case, computeOutput() depends on @M6 variable.

Examples

checkInput

def checkInput(di, oldvalue):
    rec = di.get_dtp_record()
    compl_in_perc=rec.compl_in.get_value() #DI040154
    compl_on=rec.compl_on.get_value()      #DI040155
    compl_by=rec.compl_by.get_value()      #DI040156
       
    if oldvalue == 0:
        if compl_in_perc > 99 and compl_on > 0 and compl_by != "":
            return True
        else:
            return False
    else:
        return True
    
# either:
#checkInput.deps = ('DI040154', 'DI040156', 'DI040155', )
# or:
checkInput.deps = ('compl_in', 'compl_on', 'compl_by', )

def checkInput(di, oldvalue):
    rec = di.get_dtp_record()
    compl_in_perc=rec.compl_in.get_value() #DI040154
    compl_on=rec.compl_on.get_value()      #DI040155
    compl_by=rec.compl_by.get_value()      #DI040156
       
    if oldvalue == 0:
        if compl_in_perc > 99 and compl_on > 0 and compl_by != "":
            return True
        else:
            return False
    else:
        return True
    
checkInput.deps = ('DI040154', 'DI040156', 'DI040155', )

computeOutput

def computeOutput(di): 
    rec = di.get_dtp_record() 
     
    panel_title = rec.get_di_by_id(57816).get_value() 
    mod_title = rec.get_di_by_id(1588).get_value()
     
    if panel_title == None or panel_title == '': 
        return str(mod_title) 
    else: 
        return str(panel_title) 
 
computeOutput.deps = ('DI057816', 'DI001588', )

processInput

def processInput(di, oldvalue):
    dtpRec = di.get_dtp_record()
    diVal = di.get_value()
    name = dtpRec.name.get_value()       #DI001589
    dt_id = dtpRec.dt_title.get_value()  #DI003389
    if name == "":
        dtpRec.name.set_string_value(str(dt_id))
    else:
        dtpRec.name.set_string_value(str(name))
    return str(diVal)

# either:
#processInput.deps = ('DI001589', 'DI003389', )
# or:
processInput.deps = ('name', 'dt_title', )

def processInput(di, oldvalue):
    dtpRec = di.get_dtp_record()
    diVal = di.get_value()
    name = dtpRec.name.get_value()       #DI001589
    dt_id = dtpRec.dt_title.get_value()  #DI003389
    if name == "":
        dtpRec.name.set_string_value(str(dt_id))
    else:
        dtpRec.name.set_string_value(str(name))
    return str(diVal)

processInput.deps = ('DI001589', 'DI003389', )

computeSqlValueRange

def computeSqlValueRange(dt_name):
    """Calculate the number of data area assignments"""
    val = """
                select count(*)
                from DT406
                where di000969={0}.di000198
            """.format(dt_name)
    
    return str(val)