Parameter and XML

Within PyMoDAQ, Parameter state are often saved or transferred (for instance when using TCP/IP) as a XML string whose Tree structure is well adapted to represent the Parameter tree structure. Below are all the functions used to convert from a Parameter to a XML string (or file) and vice-versa.

pymodaq.daq_utils.parameter.ioxml.walk_parameters_to_xml(parent_elt=None, param=None)[source]

To convert a parameter object (and children) to xml data tree.

Parameters Type Description
parent_elt XML element the root element
param instance of pyqtgraph parameter Parameter object to be converted
Returns:XML element – XML element with subelements from Parameter object
Return type:parent_elt
pymodaq.daq_utils.parameter.ioxml.walk_xml_to_parameter(params=[], XML_elt=None)[source]

To convert an XML element (and children) to list of dict enabling creation of parameter object.

Parameters Type Description
params dictionnary list the list to create parameter object
XML_elt XML object the XML object to be converted
Returns:params – list of dict to create parameter object
Return type:dictionnary list


>>> from pyqtgraph.parametertree import Parameter, ParameterItem
>>> import xml.etree.ElementTree as ET
>>> tree = ET.parse('text_bis.xml')
>>> root = tree.getroot()
>>> params=walk_xml_to_parameter(XML_elt=root)
>>> settings_xml=Parameter.create(name='Settings XML', type='group', children=params)
>>> settings=Parameter.create(name='Settings', type='group', children=params)
pymodaq.daq_utils.parameter.ioxml.add_text_to_elt(elt, param)[source]

Add a text filed in a xml element corresponding to the parameter value

  • elt (XML elt) –
  • param (Parameter) –
pymodaq.daq_utils.parameter.ioxml.set_txt_from_elt(el, param_dict)[source]

get the value of the parameter from the text value of the xml element :param el: :type el: xml element :param param_dict: :type param_dict: dictionnary from which the parameter will be constructed


Get Parameter properties as a dictionary

Parameters:param (Parameter) –
Return type:dict

Convert xml element attributes to a dictionnary


Convert a Parameter to a XML string.

Parameters:param (Parameter) –
Return type:XMl string


>>> from pyqtgraph.parametertree import Parameter
>>>    #Create an instance of Parameter
>>> settings=Parameter(name='settings')
>>> converted_xml=parameter_to_xml_string(settings)
>>>    # The converted Parameter
>>> print(converted_xml)
b'<settings title="settings" type="None" />'
pymodaq.daq_utils.parameter.ioxml.parameter_to_xml_file(param, filename)[source]

Convert the given parameter to XML element and update the given XML file.

Parameters Type Description
param instance of pyqtgraph parameter the parameter to be added
filename string the filename of the XML file



Convert a xml file into pyqtgraph parameter object.

Parameters Type Description
file_name string the file name of the XML file to be converted
Returns:params – a parameter list of dictionnary to init a parameter
Return type:dictionnary list



Convert a xml string into a list of dict for initialize pyqtgraph parameter object.

Parameters Type Description
xml_string string the xml string to be converted
Return type:a parameter list of dict to init a parameter