Hey, 

I am implementing simple workflow engine and i have a concept of a workflow and a workflow instance. Workflow can operate on a selected model, therefore the workflow instances of that workflow will contain the reference to an instance of that model.

I am trying to use the reference field to select any model in the database with some constraints.

class eaxpl_workflow(models.Model):

    _name = 'eaxpl.workflow'

    document_model_id = fields.Many2one('ir.model',)

class eaxpl_workflow_instance(models.Model):

    _name = 'eaxpl.workflow_instance'

    workflow_id = fields.Many2one('eaxpl.workflow', string="Workflow", required=True)

    document_model_id = fields.Many2one('ir.model', related='workflow_id.document_model_id')

    document_reference = fields.Reference(selection=?????)

The question is what to put in the place of the question marks to limit the selection of the models to the model loaded to the document_model_id field?

I have found the following snippet but it seems not to have the context of the current record and simply does not work:

    @api.model

    def _reference_models(self):

        models = self.env['ir.model'].sudo().search(

            [('state', '!=', 'manual')])

        return [(model.model, model.name)

                for model in models

                if not model.model.startswith('ir.')]

Also, when used as a selection attribute, the function seems to be called only once, so I see no way of updating this.

How would you approach this?