improvement: support default_prefix configuration

Author: zachdaniel

lib/data_layer.ex

@@ -1603,7 +1603,7 @@ defmodule AshPostgres.DataLayer do
             query_tenant) do
       Ecto.Query.put_query_prefix(query, query_tenant || root_tenant)
     else
-      %{query | prefix: "public"}
+      %{query | prefix: repo(relationship.destination).config()[:default_prefix] || "public"}
     end
   end
 
@@ -1631,7 +1631,10 @@ defmodule AshPostgres.DataLayer do
             query_tenant) do
       Ecto.Query.put_query_prefix(query, query_tenant || root_tenant)
     else
-      %{query | prefix: "public"}
+      %{
+        query
+        | prefix: repo(relationship.destination).config()[:default_prefix] || "public"
+      }
     end
   end
 
@@ -2263,9 +2266,12 @@ defmodule AshPostgres.DataLayer do
 
   defp set_join_prefix(join_query, query, resource) do
     if Ash.Resource.Info.multitenancy_strategy(resource) == :context do
-      %{join_query | prefix: query.prefix}
+      %{join_query | prefix: query.prefix || "public"}
     else
-      %{join_query | prefix: "public"}
+      %{
+        join_query
+        | prefix: repo(resource).config()[:default_prefix] || "public"
+      }
     end
   end
 

lib/repo.ex

@@ -33,6 +33,8 @@ defmodule AshPostgres.Repo do
   @callback tenant_migrations_path() :: String.t()
   @doc "The path where your migrations are stored"
   @callback migrations_path() :: String.t()
+  @doc "The default prefix(postgres schema) to use when building queries"
+  @callback default_prefix() :: String.t()
 
   defmacro __using__(opts) do
     quote bind_quoted: [opts: opts] do
@@ -45,6 +47,7 @@ defmodule AshPostgres.Repo do
       def installed_extensions, do: []
       def tenant_migrations_path, do: nil
       def migrations_path, do: nil
+      def default_prefix, do: "public"
 
       def all_tenants do
         raise """
@@ -65,11 +68,16 @@ defmodule AshPostgres.Repo do
           |> Keyword.put(:installed_extensions, installed_extensions())
           |> Keyword.put(:tenant_migrations_path, tenant_migrations_path())
           |> Keyword.put(:migrations_path, migrations_path())
+          |> Keyword.put(:default_prefix, default_prefix())
 
         {:ok, new_config}
       end
 
-      defoverridable init: 2, installed_extensions: 0, all_tenants: 0, tenant_migrations_path: 0
+      defoverridable init: 2,
+                     installed_extensions: 0,
+                     all_tenants: 0,
+                     tenant_migrations_path: 0,
+                     default_prefix: 0
     end
   end
 end