Ash Elixir•3y ago

Better way to do this query?

I have a simple search action for an autocomplete, and I want to have it skip the filter if the search term is "" in order to just return the top sorted options. I have a pretty simple solution, but was wondering if there's a cleaner/more idiomatic way of doing it:

    read :autocomplete do
      argument :search, :ci_string

      prepare fn query, _ ->
        search_string = Ash.Query.get_argument(query, :search)

        query
        |> Ash.Query.filter(
          if ^search_string != "", do: contains(name_email, ^search_string), else: true
        )
        |> Ash.Query.load(:name_email)
        |> Ash.Query.sort(:name_email)
        |> Ash.Query.limit(10)
      end
    end

    read :autocomplete do
      argument :search, :ci_string

      prepare fn query, _ ->
        search_string = Ash.Query.get_argument(query, :search)

        query
        |> Ash.Query.filter(
          if ^search_string != "", do: contains(name_email, ^search_string), else: true
        )
        |> Ash.Query.load(:name_email)
        |> Ash.Query.sort(:name_email)
        |> Ash.Query.limit(10)
      end
    end

If not, no problem, this works fine. 🙂

11 Replies

ZachDaniel•3y ago

🤔 Can search_string ever be ""? IIRC we trim strings by default

frankdugan3OP•3y ago

Seems to work as expected. When I empty the search field, I get the top 10, when I enter any character it starts filtering. Trim can produce an empty string, right? That's what I'm matching on.

ZachDaniel•3y ago

Sorry, its actually allow_empty? which defaults to false and should be doing "" -> nil if its not then something weird is going on TBH

frankdugan3OP•3y ago

Oh, interesting... When I inspect the search term, it is nil. :thinkinghard: Is it because of the interpolation?

ZachDaniel•3y ago

oh, lol search_string != "" is false when search_string is NULL

frankdugan3OP•3y ago

iex(46)> nil != ""
true
iex(47)> "#{nil}" != ""
false

iex(46)> nil != ""
true
iex(47)> "#{nil}" != ""
false

ZachDaniel•3y ago

because ash expressions are SQL-ish

frankdugan3OP•3y ago

Yeah, that makes sense. Which is all good, that's the behavior I'm looking for.

ZachDaniel•3y ago

well, technically it evalutest to NULL but yeah it causes the else branch to run

frankdugan3OP•3y ago

I'm just wondering if there's a better abstraction for this sort of "don't filter empty search strings" idea. I'll be writing a lot of these kinds of actions. And some of them will have much more complex filtering.

ZachDaniel•3y ago

Hm…maybe a custom helper macro like filter_if(predicate, …)

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Better way to do this query?

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