I want to produce this xml file with python and minidom:
<xml vesion="1.0" encoding="utf-8?>
<package name="Operation" xmlns="http://www.modelIL.eu/types-2.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation = "http://www.modelIL.eu/types-2.0 modelIL-package-2.0.xsd">
</package>
I have wrote this:
import xml.dom.minidom as dom
document = dom.Document()
root_xml = document.createElement("package")
root_xml.setAttribute("name", "Operation")
root_xml.setAttributeNS("", "xmlns", "http://www.modelIL.eu/types-2.0")
root_xml.setAttributeNS("xmls", "xsi", "http://www.w3.org/2001/XMLSchema-instance")
root_xml.setAttribute("xsi:schemaLocation", "http://www.modelIL.eu/types-2.0 modelIL-package-2.0.xsd")
root = document.appendChild(root_xml)
print(document.toprettyxml(indent(" "))
But the output I get is this one:
<xml vesion="1.0" ?>
<package name="Operation" xmlns="http://www.modelIL.eu/types-2.0" xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation = "http://www.modelIL.eu/types-2.0 modelIL-package-2.0.xsd">
</package>
Why do I have only xsi and not xmlns:xsi? Did I forget something?
Full disclosure: I do not use minidom for XML, I use lxml and on top of that I do not use XML that often, so I hope my answer will be useful.
One might expect that by setting an attribute with a particular namespace, there would not be any need to explicitly state a prefix to appear before the local name in the final, written XML document - after all, it should be possible to detect that a namespace has been employed and that a prefix is required in the full attribute name so that the attribute is recognised as being associated with that namespace. Unfortunately, we do not seem to have that luxury and must explicitly specify a prefix as part of the qualified name when setting such an attribute
Python and XML: An Introduction (skip to the Atributes part)
This should solve your problem:
root_xml.setAttributeNS("xmls", "xmlns:xsi", "http://www.w3.org/2001/XMLSchema-instance")
As you know the setAttributeNS method takes three arguments: namespaceURI, qualifiedName, value. The attribute is than added if the element has no attribute with the same namespaceURI and localname - we get the localname by doing a split on qualifiedName using the function _nssplit. Otherwise the method tries to update the value of the attribute.
However the name of the attribute is a combination of prefix (the part of the qualifiedName before the colon punctuation) and localname "%s:%s" % (prefix, localName). If no prefix is present the name of the attribute is the same as the qualifiedName argument.
If you do not care for the namespaceURI of your attributes you could achieve the same result using only the setAttribute method like you did with the first and last attribute. In that case the method will look for an attribute with the same attribute name. If it finds one, it will try to overwrite it's value.
I do have one question: why do you bind root = document.appendChild(root_xml)? Is it to avoid the return value in your REPL? That I understand.