Elasticsearch-dsl-py: How to set default values for document fields

[thephysicsriot]

Hello,

I have a simple class that looks like the following:

class Person(DocType):

    name = Text(fields={
        'keyword': Keyword(),
        })
    date_created = Date()
    seen_count = Integer()
    ...

I would like to default the date_created field to now and the seen_count field to 1 and set other defaults for fields not listed here.

I found this test that shows a default being set by using the clean function of an intermediate class. https://github.com/elastic/elasticsearch-dsl-py/blob/master/test_elasticsearch_dsl/test_validation.py#L27

Since the commit is from 2 years ago, I'm wonder if this is still the easiest/best/proper way to do field defaults. Thanks for the help!

[HonzaKral]

Hi, that is definitely one way to do it, but I would recommend more for a field that you then wish to reuse. If you have a document that you wish to have some default values for, I'd personally just override .save() and set the values there if they are not set.

Hope this helps!

[serain]

I'm also looking at setting some default values on object creation.

@HonzaKral what if you want to reference the default values before .save() has been called?

class Thing(DocType):
    uuid = Keyword()

    # your suggestion
    def save(self, **kwargs):
        self.uuid = uuid.uuid4()
        return super().save(**kwargs)


thing = Thing()

# but what if I want to access the generated UUID before I've called .save()?
print(thing.uuid)

thing.save()

A use case would be, for example, initializing other fields that depend on a field being set to datetime.now() or a UUID or some other default value.

I'm currently defining my own init() method and using that after instantiating the object. Just wondering if there's a recommended way to do it?