Get columns names with ActiveRecord
Is there a way to get the actual columns name with ActiveRecord?
When I call find_by_sql or select_all with a join, if there are columns with the same name, the first one get overridden:
select locations.*, s3_images.* from locations left join s3_images on s3_images.imageable_id = locations.id and s3_images.imageable_type = 'Location' limit 1
In the example above, I get the following:
#<Location id: 22, name: ...
>
Where id is that of the last s3_image. select_rows is the only thing that worked as expected:
Model.connection.select_rows("SELECT id,name FROM users") => [["1","amy"],["2","bob"],["3","cam"]]
I need to get the field names for the rows above. This post gets close to what I want but looks outdated (fetch_fields doesn't seem to exist anymore How do you get the rows and the columns in the result of a query with ActiveRecord? )
The ActiveRecord join method creates multiple objects. I'm trying to achieve the same result "includes" would return but with a left join.
I am attempting to return a whole lot of results (and sometimes whole tables) this is why includes does not suit my needs.
Active Record provides a #column_names method that returns an array of column names.
Usage example: User.column_names
two options
Model.column_names
or
Model.columns.map(&:name)
Example Model named Rabbit with columns name, age, on_facebook
Rabbit.column_names
Rabbit.columns.map(&:name)
returns
["id", "name", "age", "on_facebook", "created_at", "updated_at"]
This is just way active record's inspect method works: it only lists the column's from the model's table. The attributes are still there though
record.blah
will return the blah attribute, even if it is from another table. You can also use
record.attributes
to get a hash with all the attributes.
However, if you have multiple columns with the same name (e.g. both tables have an id column) then active record just mashes things together, ignoring the table name.You'll have to alias the column names to make them unique.