empty attributes are removed in generated XML

[gjvc]

Hello,
First of all, thank you for a wonderful project. It's a great leap forward over walking XML trees via ElementTree findall() and such.

I am using it to generate a configuration for a system. This is a legacy application and as such has many quirks. One such quirk is that it needs to see an empty attribute in an element like this

<element something="hello" else="there" amount="" symbol="ABC" />

The problem I'm having is that amount="" is getting removed and does not appear in the generated XML, even when I set it to "". I would expect it to be removed if it were set to None in Python, but i'm setting it to the empty string and that is what I would like to see in the XML. I'm using xsdata version 20.7 on python 3.8.5.

[tefra]

You are right the serializer is ignoring empty strings as well, that doesn't sound right.

Let me run a few tests to see if we can change this default behavior or if we need to add some sort of configuration there.

Same behavior for v20.8 as well

[tefra]

Out of curiosity @gjvc are you working with a schema definition or do you write the models yourself? Also did you encounter an issue with v20.8 and didn't upgrade?

[gjvc]

Out of curiosity @gjvc are you working with a schema definition or do you write the models yourself? Also did you encounter an issue with v20.8 and didn't upgrade?

Thank you very much for the quick response! I am using an XSD generated from a RelaxNG grammar via the "trang" tool.

I tried v20.8 to see if it fixed this problem (which it didn't)[1], but held off making this problem report until I'd gone through the documentation one more time :-)

[1] I will try the latest version

[tefra]

Can you share how that attribute is defined in the xsd?

[gjvc]

Currently it is defined in the XSD as

   <xs:attribute name="orderQty" type="xs:integer"/>

I am able (and might need) to change this to "xs:string", because in some cases the value is of the format "1000|2000|3000" (as I said, legacy system :-))

[gjvc]

I have just tried your fix via this in my etc/pip/requirements.txt file

-xsdata==20.7
+git+https://github.com/tefra/xsdata.git@issue-230

...and it looks like it works great. Thank you very much for the amazingly quick fix. :-)

[tefra]

awesome man, I also confirmed with the w3c-test-suite that the updated behavior still produces valid xml instances.

I am going to merge it to master, and it will be included in the next release v20.9, make sure you switch to the master branch till then.