Hi, I’m new to Elixir and trying to probe the GraphQL things. I’d like to understand how to use the import_sdl macro with the hydrate function to match resolvers to the imported schema. My sample setup looks like this:
SDL File
type Person {
lastName: String!
firstName: String!
id: String!
phoneNumbers: [String]
}
type Query {
getPersonById(id: String!): Person
getPeople: [Person]!
}
defmodule GqlHydrateWeb.Schema do
@moduledoc false
use Absinthe.Schema.Notation
import_sdl path: "assets/sdl/sample-schema.graphql"
# Where/how do I call the hydrate function provided with the resolver? Or is that defined here?
end
Resolver File
defmodule GqlHydrateWeb.Resolvers.GetPeople do
def resolve_get_people(a,b,c) do
%{
lastName: 'Smith',
firstName: 'Joe',
id: '9ap8sodh'
}
end
# Adapted from the Absinthe Docs
def hydratePeople(%{identifier: :getPeople}, [%{identifier: :query} | _]) do
{:resolve, &__MODULE__.resolve_get_people/3}
end
end
I can write the hydrate function, but I don’t quite know how to integrate that into the schema building process so that this is called within the right context. Is there a sample somewhere that I can look at to see how this pattern can be used?
Your hydate function doesn’t look like ours, so maybe the docs are suggesting a different approach, but our code looks something like this:
defmodule GqlHydrateWeb.Schema do
@moduledoc false
use Absinthe.Schema.Notation
import_sdl path: "assets/sdl/sample-schema.graphql"
def hydrate(%Absinthe.Blueprint{}, _) do
%{query: %{get_people: [resolve: &GqlHydrateWeb.Resolvers.GetPeople.resolve_get_people/2]}}
end
def hydrate(_node, _ancestors), do: []
end
Ok - I think I understand my misunderstanding. I thought that the sample in the docs was a function that I would attach to a lifecycle hook, when, in fact, it’s literally calling the Schema.hydrate function on initialization. Then you have a hydrate function per required resolver that matches against each node in the schema (as Absinthe will iterate through each node calling hydrate on setup).
If you are very new to Elixir, and in particular if you are new to functional programming, I would strongly suggest taking a beat to get comfortable with the language before diving into Absinthe as its docs generally expect a general familiarity with Elixir and Phoenix.
Thanks for the help! I didn’t quite catch the nuance in the examples that the schema.ex file needed to import the top level Absinthe.Schema.
I think the functional aspect of the language is pretty natural for me. However there are some definite quirks - for example, Absinthe’s autoconversion of field names from camel case to snake case definitely got me for a bit. But this has definitely been a fun exploration!
Again, I really appreciate your time and assistance!
