Saša’s article made me wish that every function in Ecto.Repo were overrideable. I’m not really a fan of fetch/transact, so would prefer to override one/get/get_by/transaction instead.
I get that this is largely incompatible with the way things work, but I wish there were some solution that basically allowed me to override parts of Ecto.Repo but keep everything else. The only way I could figure out how to do it was to create a wrapper module.
Wrapping has its problems though - I have to defdelegate all non-overrided functions to the BaseRepo module and reference BaseRepo for configuration.
I wish there were a way to tell Ecto that I’m wrapping a repo so whenever it sees WrappedRepo it would actually use BaseRepo for config and the “private” functions (e.g. Ecto.Repo.Schema.insert(...)).
It’s not really that big of a deal, but Ecto letting us define custom wrappers around the repo would really improve code ergonomics. I’m fine with handling the incompatibility of external libraries expecting the repo to work like a normal non-overrided repo.
If the code police is reading this, I plead the fifth. If you have any ideas about how to do what I’m trying to do, I definitely want to hear them.
bad, illegal, offensive code
defmodule DM.Repo do
alias DM.BaseRepo
def one(queryable, opts \\ []) do
case BaseRepo.one(queryable, opts) do
nil -> {:error, :not_found}
record -> {:ok, record}
end
end
def get(queryable, id, opts \\ []) do
case BaseRepo.get(queryable, id, opts) do
nil -> {:error, :not_found}
record -> {:ok, record}
end
end
def get_by(queryable, clauses, opts \\ []) do
case BaseRepo.get_by(queryable, clauses, opts) do
nil -> {:error, :not_found}
record -> {:ok, record}
end
end
def transaction(fun, opts \\ []) when is_function(fun) do
BaseRepo.transaction(
fn repo ->
result =
case Function.info(fun, :arity) do
{:arity, 0} -> fun.()
{:arity, 1} -> fun.(repo)
end
case result do
{:ok, result} -> result
{:error, reason} -> repo.rollback(reason)
end
end,
opts
)
end
# query API
defdelegate aggregate(queryable, aggregate, opts \\ []), to: BaseRepo
defdelegate aggregate(queryable, aggregate, field, opts), to: BaseRepo
defdelegate all(queryable, opts \\ []), to: BaseRepo
defdelegate delete_all(queryable, opts \\ []), to: BaseRepo
defdelegate exists?(queryable, opts \\ []), to: BaseRepo
defdelegate get!(queryable, id, opts \\ []), to: BaseRepo
defdelegate get_by!(queryable, clauses, opts \\ []), to: BaseRepo
defdelegate one!(queryable, opts \\ []), to: BaseRepo
defdelegate stream(queryable, opts \\ []), to: BaseRepo
defdelegate update_all(queryable, updates, opts \\ []), to: BaseRepo
# schema API
defdelegate delete(struct_or_changeset, opts \\ []), to: BaseRepo
defdelegate delete!(struct_or_changeset, opts \\ []), to: BaseRepo
defdelegate insert(struct_or_changeset, opts \\ []), to: BaseRepo
defdelegate insert!(struct_or_changeset, opts \\ []), to: BaseRepo
defdelegate insert_all(schema_or_source, entries_or_query, opts \\ []), to: BaseRepo
defdelegate insert_or_update(changeset, opts \\ []), to: BaseRepo
defdelegate insert_or_update!(changeset, opts \\[]), to: BaseRepo
defdelegate load(schema_or_map, data), to: BaseRepo
defdelegate preload(structs_or_struct_or_nil, preloads, opts \\ []), to: BaseRepo
defdelegate reload(struct_or_structs, opts \\ []), to: BaseRepo
defdelegate reload!(struct_or_structs, opts \\ []), to: BaseRepo
defdelegate update(changeset, opts \\ []), to: BaseRepo
defdelegate update!(changeset, opts \\ []), to: BaseRepo
# transaction API
defdelegate checked_out?(), to: BaseRepo
defdelegate checkout(function, opts \\ []), to: BaseRepo
defdelegate in_transaction?(), to: BaseRepo
defdelegate rollback(value), to: BaseRepo
# runtime API
defdelegate __adapter__(), to: BaseRepo
defdelegate get_dynamic_repo(), to: BaseRepo
defdelegate put_dynamic_repo(name_or_pid), to: BaseRepo
defdelegate start_link(opts \\ []), to: BaseRepo
defdelegate stop(timeout \\ 5000), to: BaseRepo
defdelegate disconnect_all(interval, opts \\ []), to: BaseRepo
defdelegate explain(type, query, opts \\ []), to: BaseRepo
defdelegate query(sql, params, opts \\ []), to: BaseRepo
defdelegate query!(sql, params, opts \\ []), to: BaseRepo
defdelegate query_many(sql, params, opts \\ []), to: BaseRepo
defdelegate query_many!(sql, params, opts \\ []), to: BaseRepo
defdelegate to_sql(type, query), to: BaseRepo
end
defmodule DM.BaseRepo do
use Ecto.Repo,
otp_app: :dm,
adapter: Ecto.Adapters.Postgres
end
)
