add custom mixin classes

[leo-b]

Hi!

First of all thanks for providing such cool XML bindings!
Generating code using python dataclasses really produces the most beautiful and clearly arranged representations of my bloated XML structures.

In my project I'd like to enrich the data container object hierarchy generated by xsdata (which is based on a externally provided xsd schema) by my own methods that add some custom logic.

My idea is to extend the dataclass output by automatically adding mixin classes from a custom module that is specified during model generation.
Those custom classes should be automatically added to my generated dataclasses as additional base classes.

Do you think this could make sense and would be possible with reasonable effort?
Could you give some hints how to implement this? Are class extensions the correct place to add the mixins?

Example:

• code generated by xsdata without custom mixins:

@dataclass
class AddressList:
    class Meta:
        name = "addressList"

    adresse: List[Address] = field(
        default_factory=list,
        metadata={
            "type": "Element",
            "min_occurs": 1,
        }
    )

• my custom_mixin_classes.py:

class MyAddressList:
    class Meta:
        name = "addressList"

    def get_primary_addr(self):
       # custom code to compute primary address

• code generated by xsdata with custom mixins:

from custom_mixin_classes import MyAddressList

@dataclass
class AddressList(MyAddressList):
    class Meta:
        name = "addressList"

    adresse: List[Address] = field(
        default_factory=list,
        metadata={
            "type": "Element",
            "min_occurs": 1,
        }
    )

Cheers,
--leo

[tefra]

Something like an output configuration something like this?

  <Modifications>
    <Class qualname="generated.models.AddressList">
      <AddBaseClass qualname="custom.mixins.MyAddressList"/>
    </Class>
  </Modifications>

[rvalyi]

We would be interested in this too, like to plug custom Python validators...
cc @renatonlima

BTW, may be I did it wrong, but in my xsdata-odoo plugin (inspired from your xsdata-plantuml plugin, I tried to have custom configuration options and that didn't seem easy because from what I remember it would load the default GeneratorConfig class before even loading my plugin and in GeneratorConfig the attributes seem fixed. So if you touch the GeneratorConfig and have some idea to make this easier...

[leo-b]

Something like an output configuration something like this?

Or maybe just configure a python module name, enumerate over the classes in that module and use class Meta info to connect them to the superclass? (Just like the parser finds the correct class for the root node if no clazz argument is specified.) This would reduce the config overhead if there are many mixins to attach.

[tefra]

Hey @leo-b

I added the ability to extend generated models with base classes and custom decorators
https://xsdata.readthedocs.io/en/latest/examples/extending-models.html

The update is on master wave