lkananowicz
Custom column names in fragment
Is there a way to use custom/varying column names in fragment? I mean the situation where I have 2 almost similar tables coming from different databases. Only couple of columns are different for historical reasons and I use those column names inside fragment(s). I want to unify Ecto queries to both of those tables as they were executed separately before.
Using simple questionmark notation fragment("?", column_name) causes column name to be appended into fragment however column ends up wrapped into double-quotes which is not desired.
Here is an example:
{:ok, datetime} = DateEx.convert_date_to_datetime(date)
CheapestConnection
|> where([cc], cc.kind == "round_trip_recent")
|> order_by([cc], fragment("abs(date_part('day', departure_date - ?)), price", type(^datetime, :utc_datetime)))
|> CheapestConnectionsRepo.all()
The column I would like to choose depending on certain conditions (like DB/Repo is used) is departure_date. That column name is different in another database. As a side note this query basically orders records by closest date relative to datetime.
Most Liked
fuelen
You can solve this by defining the same field with different sources in schemas
defmodule Schema1 do
schema "table1" do
field(:custom_column_name, :utc_datetime, source: :column_name1
end
end
defmodule Schema2 do
schema "table2" do
field(:custom_column_name, :utc_datetime, source: :column_name2
end
end
schema_module
|> where([cc], cc.kind == "round_trip_recent")
|> order_by([cc], fragment("abs(date_part('day', ? - ?)), price", cс.custom_column_name, type(^datetime, :utc_datetime)))
|> CheapestConnectionsRepo.all()
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