In my first Phoenix app, I have an action which serves an XML phonebook to a certain SIP handset. The handset has two ways of calling this action:
/gigaset?reqsrc=user&ln=foo # Search for a contact with the name 'foo'
/gigaset?reqsrc=auto&hm=12345 # Search for a contact with caller ID 12345
Since both have different queries I decided to pattern match based on the reqsrc parameter. But both action have some shared logic as well, so I put that in a separate method with the same name but different arity to apply limit and offset and render the view/template. It works, but is this the right way of doing things?
# User quering phonebook from Gigaset base
def gigaset(conn, params = %{"reqsrc" => "user"}) do
name = String.replace(params["ln"], "*", "%")
query = from e in Entry, where: ilike(e.name, ^name)
gigaset conn, query, params
end
# Caller ID from Gigaset base
def gigaset(conn, params = %{"reqsrc" => "auto"}) do
number = params["hm"]
query = from e in Entry, where: e.work == ^number or e.home == ^number or e.mobile == ^number
gigaset conn, query
end
# Finish query, render output
def gigaset(conn, query, params) do
limit = String.to_integer(params["count"])
offset = String.to_integer(params["first"]) - 1
query = from e in query, limit: ^limit, offset: ^offset
entries = Repo.all(query)
render conn, entries: entries
end
I know the difference in the query is trivial, but imagine they would be vastly different. Does it make sense to do it like this?
Waitā¦ after testing it again it seems to not work as expected
Requesting /gigaset?reqsrc=auto yields a āno matching action clause to process requestā error on the definition of the first method. Is there a way to do this, at all?
I ended up rewriting into this long method (with some more changes):
def gigaset(conn, params = %{ "reqsrc" => reqsrc, "count" => limit, "first" => offset }) do
query = case reqsrc do
# User quering phonebook from Gigaset base
"user" ->
name = String.replace(params["ln"], "*", "%")
from e in Entry, where: ilike(e.name, ^name)
# Caller ID from Gigaset base
"auto" ->
number = params["hm"]
from e in Entry, where: e.work == ^number or e.home == ^number or e.mobile == ^number
end
# Total before pagination
total = Repo.one(from e in query, select: count(e.id))
# Paginated entries
offset = String.to_integer(offset) - 1
query = from e in query, limit: ^limit, offset: ^offset
entries = Repo.all(query)
render conn, entries: entries, total: total, offset: offset
end
All feedback is welcome! I realise some of this belongs in the model probably.
I donāt think thereās any problem in using pattern matching in controller methods. Iāve done this in one of my projects myself and it works great:
def insert_attachment(conn, %{"ticket_message" => ticket_message,
"ticket_id" => ticket_id}) do
ticket = Repo.get(Ticket, ticket_id)
upload = Map.get(ticket_message, "file")
TicketAttachmentController.insert(conn, ticket, upload)
end
def insert_attachment(conn, %{"ticket_id" => ticket_id}) do
conn
|> put_flash(:error, "No file was selected.")
|> redirect(to: ticket_path(conn, :show, ticket_id))
end
Your match does only āfireā when you have all the parameters "reqsrc", "count", and "first" available. In the requested āpathā /gigaset?reqsrc=auto" there is only "reqsrc" available, so you need to add another clause after your current one, which needs to be like this: