From 8f79fcb59ddaef5a9542cec24f374a6e21ea5f3f Mon Sep 17 00:00:00 2001
From: Jesse Williams <jesse@albert.io>
Date: Thu, 18 Jul 2024 13:37:31 -0700
Subject: [PATCH] fix: allow non-unique has_many source_attributes (#355)

* fix: allow non-unique has_many source_attributes

* fix composite primary key case
---
 lib/data_layer.ex | 36 +++++++++++++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/lib/data_layer.ex b/lib/data_layer.ex
index 1602df4..b0676b6 100644
--- a/lib/data_layer.ex
+++ b/lib/data_layer.ex
@@ -1044,9 +1044,43 @@ defmodule AshPostgres.DataLayer do
       {:ok, data_layer_query} ->
         source_values = Enum.map(root_data, &Map.get(&1, source_attribute))
 
+        source_filter =
+          case source_pkey do
+            [] ->
+              Ecto.Query.dynamic([source], field(source, ^source_attribute) in ^source_values)
+
+            [field] ->
+              values = Enum.map(root_data, &Map.get(&1, field))
+              Ecto.Query.dynamic([source], field(source, ^field) in ^values)
+
+            fields ->
+              Enum.reduce(root_data, nil, fn record, acc ->
+                row_match =
+                  Enum.reduce(fields, nil, fn field, acc ->
+                    if is_nil(acc) do
+                      Ecto.Query.dynamic(
+                        [source],
+                        field(source, ^field) == ^Map.get(record, field)
+                      )
+                    else
+                      Ecto.Query.dynamic(
+                        [source],
+                        field(source, ^field) == ^Map.get(record, field) and ^acc
+                      )
+                    end
+                  end)
+
+                if is_nil(acc) do
+                  row_match
+                else
+                  Ecto.Query.dynamic(^row_match or ^acc)
+                end
+              end)
+          end
+
         data_layer_query =
           from(source in data_layer_query,
-            where: field(source, ^source_attribute) in ^source_values
+            where: ^source_filter
           )
 
         if query.__ash_bindings__[:__order__?] do