Mongo.Ecto.Helpers.change_map

You're seeing just the function change_map, go back to Mongo.Ecto.Helpers module for more information.
Link to this function

change_map(field, value)

View Source

Specs

change_map(String.t(), term()) :: Mongo.Ecto.ChangeMap.t()

Allows updating only a fragment of a nested document

Usage in queries

MyRepo.update_all(Post,
  set: [meta: change_map("author.name", "NewName")])