beremiz

Proper fix for error 'object has no attribute 'getSlave' in EtherCAT extension

2018-08-24, Andrey Skvortsov
96ca6b056c55
file isExecutable
Proper fix for error 'object has no attribute 'getSlave' in EtherCAT extension

traceback:
File "/home/developer/WorkData/PLC/beremiz/beremiz/IDEFrame.py", line 1433, in OnPouSelectedChanged
window.RefreshView()
File "/home/developer/WorkData/PLC/beremiz/beremiz/etherlab/ConfigEditor.py", line 837, in RefreshView
self.RefreshProcessVariables()
File "/home/developer/WorkData/PLC/beremiz/beremiz/etherlab/ConfigEditor.py", line 886, in RefreshProcessVariables
slaves = self.Controler.GetSlaves(**self.CurrentNodesFilter)
File "/home/developer/WorkData/PLC/beremiz/beremiz/etherlab/EthercatMaster.py", line 341, in GetSlaves
for slave in self.Config.getConfig().getSlave():
:_'lxml.etree._Element'_object_has_no_attribute_'getSlave'

Steps to reproduce problem:

- Add new EtherCAT master
- Add new EthercatNode to the master
- double click on


Revert commit "Dirty fix for error '_object_has_no_attribute_'getSlave' in EtherCAT extension"
[a3ac46366b86a0b237dac93be6b2281ac70b98a8].

The problem was that XML elements (proxy object) in some cases were created using custom XML
classes constructors and lxml.etree.Element() call and live python
patching. This causes that lxml backend doesn't know that custom python class
should be used for these XML elements.
Proxy object can be move/deleted and recreated by lxml
backend at any point in time or this can be done in python by copy/deepcopy operations.
If this happens, then newly created
proxy elements are using default class lxml.etree._Element. And all
custom functionality is lost.

All created XML elements should be always created through corresponding
parser and class lookup callback done by lxml backend.
It's described in more details in lxml documentation:
https://lxml.de/element_classes.html
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<fileHeader companyName="beremiz" productName="Beremiz" productVersion="0.0" creationDateTime="2008-12-14T16:21:19"/>
<contentHeader name="Beremiz SVGUI Test" modificationDateTime="2018-08-24T13:19:27">
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<INT/>
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<type>
<derived name="Button"/>
</type>
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<variable name="Counter_TextCtrl">
<type>
<derived name="TextCtrl"/>
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</variable>
<variable name="State_LedCtrl">
<type>
<derived name="Led"/>
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<comment localId="101" height="164" width="977">
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<content>
<xhtml:p><![CDATA[This example shows how IEC program in PLC can interact with web interface.
svgui is extensions to build web interface to PLC. It has *integrated* web-server. So it's NOT necessary to install Apache, lighttpd or nginx for that!!!
As the program is running in PLC, web UI will be available at http://localhost:8009/.
Web interface is build as SVG file in Inkscape. To edit SVG file click 'Inkscape' button in 0x: svgui extension.
Inkscape is a free and open-source vector graphics editor. It's not part of Beremiz and needs to be installed separately.
]]></xhtml:p>
</content>
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<content>
<xhtml:p><![CDATA[In this example basic elements like 'Button', 'Led' and 'Text' are used.
Back_id and sele_id inputs of these blocks are IDs of graphic primitives in SVG file.
This is the way how elements in SVG are bound to elements in PLC program.
You can find out or edit these IDs in Inkscape.]]></xhtml:p>
</content>
</comment>
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<resource name="res_pytest">
<task name="pytest_task" interval="t#100ms" priority="0"/>
<pouInstance name="pytest_instance" typeName="main_pytest"/>
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