No alias field

[LasseGravesen]

An alias mapping defines an alternate name for a field in the index. The alias can be used in place of the target field in search requests.
https://www.elastic.co/guide/en/elasticsearch/reference/master/alias.html

It seems that this field is not included in elasticsearch-dsl currently.
I wanted to ask if anyone was working on adding this already, and if not could I open a PR as it would be simple to add.

[sandeshnaroju]

any update on this?

[Zacharis278]

+1 I also have a need for this. Currently have a service doing a search with an alias target and as a result it won't map back to the correct python type due to strict matching on the returned _index. That index wouldn't match the index field (which is really the alias) on my Document.

[LasseGravesen]

Here's what I did:
in helpers.py

from elasticsearch7_dsl import Field

class Alias(Field):
    """Alias field.
    https://www.elastic.co/guide/en/elasticsearch/reference/master/alias.html
    """

    name = "alias"
    _coerce = True

    def to_dict(self):
        """Return as dict."""
        d = super(Alias, self).to_dict()
        d["type"] = "alias"
        return d

Then in the template file, template.py

from helpers import Alias
from elasticsearch7_dsl import Document, InnerDoc, Integer, MetaField, Object

class Test(InnerDoc):
    """Test inner document type."""

    xyz = Alias(path="test.abc")
    abc = Integer()

class TestDoc(Document):
    """TestDoc Document class."""

    test = Object(doc_class=Test)

    class Index:
        """Specify the index meta information."""

        name = "test-docs-*"

    class Meta:
        """Add strictness to schema, new fields cannot be arbitrarily added."""

        dynamic = MetaField("strict")

When can then be used to instantiate templates on the cluster:

from template import TestDoc

def create_template():
    """Create template."""
    mentions = TestDoc._index.as_template(
        "test-docs-template", order=0
    )


def main():
    """Runnable entry point."""
    connections.create_connection(
        hosts=["https://my-es-cluster:443/"],
        alias="default",
        timeout=20,
        http_auth="abc:def",
        ssl=True,
    )
    create_template()


if __name__ == "__main__":
    main()