fix: better reduce logic

Author: Mateus Garcia

libs/json-api-nestjs/src/lib/mixin/service/transform/transform.mixin.ts

@@ -186,17 +186,21 @@ export class TransformMixinService<T> {
         const propsData = data[field];
         const typeName = getEntityName(this.relationTarget.get(field));
         if (Array.isArray(propsData)) {
-          builtData.data = propsData
-            .map((i) => ({
-              type: camelToKebab(typeName),
-              id: i[this.relationPrimaryField.get(field)].toString(),
-            }))
-            .reduce((acum, i) => {
-              if (acum.find((a) => a.id === i.id)) {
-                return acum;
-              }
-              return [...acum, i];
-            }, []);
+          const tmp = propsData.reduce((acum, item) => {
+            const key = `${camelToKebab(typeName)}:${item[
+              this.relationPrimaryField.get(field)
+            ].toString()}`;
+
+            if (!acum.has(key)) {
+              acum.set(key, {
+                type: camelToKebab(typeName),
+                id: item[this.relationPrimaryField.get(field)].toString(),
+              });
+            }
+
+            return acum;
+          }, new Map());
+          builtData.data = [...tmp.values()];
         }
 
         if (!Array.isArray(data[field]) && typeof data[field] !== 'undefined') {