Function as model column in Flask Admin

I like the idea about separation of business logic from models and views into services. There are more details in these slides from the EuroPython talk.

Usually in Flask-Admin for a new column a new method with @property decorator is added and the model becomes fat. Also it’s not good to put something with queries in property. Another way is to put this function to the services and use column formatter in Flask-Admin.

def get_some_data(model_id)
    """Function in services."""
    return RelatedModel.objects(model=model_id).count()

class MyModelView(ModelView):
    column_formatters = {
        'related_model_count': lambda view, context, model, name: get_some_data(

    column_list = [..., 'related_model_count']
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