fix persisting of many to many entity

app/src/data/relations/ManyToManyRelation.ts

@@ -105,13 +105,13 @@ export class ManyToManyRelation extends EntityRelation<typeof ManyToManyRelation
    }
 
    override getReferenceQuery(entity: Entity, id: number): Partial<RepoQuery> {
-      const conn = this.connectionEntity;
+      const { other, otherRef } = this.getQueryInfo(entity);
 
       return {
          where: {
-            [`${conn.name}.${entity.name}_${entity.getPrimaryField().name}`]: id
+            [otherRef]: id
          },
-         join: [this.target.reference]
+         join: [other.reference]
       };
    }
 
@@ -160,47 +160,27 @@ export class ManyToManyRelation extends EntityRelation<typeof ManyToManyRelation
             .whereRef(entityRef, "=", otherRef)
             .innerJoin(...join)
             .limit(limit);
-
-      /*return qb.select((eb) => {
-         const select: any[] = other.entity.getSelect(other.entity.name);
-         // @todo: also add to find by references
-         if (additionalFields.length > 0) {
-            const conn = this.connectionEntity.name;
-            select.push(
-               jsonBuildObject(
-                  Object.fromEntries(
-                     additionalFields.map((f) => [f.name, eb.ref(`${conn}.${f.name}`)])
-                  )
-               ).as(this.connectionTableMappedName)
-            );
-         }
-
-         return jsonFrom(
-            eb
-               .selectFrom(other.entity.name)
-               .select(select)
-               .whereRef(entityRef, "=", otherRef)
-               .innerJoin(...join)
-               .limit(limit)
-         ).as(other.reference);
-      });*/
    }
 
    initialize(em: EntityManager<any>) {
       this.em = em;
 
-      //this.connectionEntity.addField(new RelationField(this.source.entity));
-      //this.connectionEntity.addField(new RelationField(this.target.entity));
-      this.connectionEntity.addField(RelationField.create(this, this.source));
-      this.connectionEntity.addField(RelationField.create(this, this.target));
+      const sourceField = RelationField.create(this, this.source);
+      const targetField = RelationField.create(this, this.target);
 
-      // @todo: check this
-      for (const field of this.additionalFields) {
-         this.source.entity.addField(new VirtualField(this.connectionTableMappedName));
-         this.target.entity.addField(new VirtualField(this.connectionTableMappedName));
+      if (em.hasEntity(this.connectionEntity)) {
+         // @todo: also check for correct signatures of field
+         if (!this.connectionEntity.hasField(sourceField)) {
+            this.connectionEntity.addField(sourceField);
+         }
+         if (!this.connectionEntity.hasField(targetField)) {
+            this.connectionEntity.addField(targetField);
+         }
+      } else {
+         this.connectionEntity.addField(sourceField);
+         this.connectionEntity.addField(targetField);
+         em.addEntity(this.connectionEntity);
       }
-
-      em.addEntity(this.connectionEntity);
    }
 
    override getName(): string {

app/src/data/relations/RelationField.ts

@@ -88,7 +88,7 @@ export class RelationField extends Field<RelationFieldConfig> {
    }
 
    override async transformPersist(value: any, em: EntityManager<any>): Promise<any> {
-      throw new Error("This function should not be called");
+      throw new Error("RelationField: This function should not be called");
    }
 
    override toJsonSchema() {

app/src/data/relations/RelationMutator.ts

@@ -2,6 +2,7 @@ import type { PrimaryFieldType } from "core";
 import type { Entity, EntityManager } from "../entities";
 import {
    type EntityRelation,
+   ManyToManyRelation,
    type MutationOperation,
    MutationOperations,
    RelationField
@@ -26,11 +27,26 @@ export class RelationMutator {
     */
    getRelationalKeys(): string[] {
       const references: string[] = [];
+
+      // if persisting a manytomany connection table
+      // @todo: improve later
+      if (this.entity.type === "generated") {
+         const relation = this.em.relations.all.find(
+            (r) => r instanceof ManyToManyRelation && r.connectionEntity.name === this.entity.name
+         );
+         if (relation instanceof ManyToManyRelation) {
+            references.push(
+               ...this.entity.fields.filter((f) => f.type === "relation").map((f) => f.name)
+            );
+         }
+      }
+
       this.em.relationsOf(this.entity.name).map((r) => {
          const info = r.helper(this.entity.name).getMutationInfo();
          references.push(info.reference);
          info.local_field && references.push(info.local_field);
       });
+
       return references;
    }