fix(self-relations): use name for join fields instead of type

Author: marcjulian

__tests__/dbml.test.ts

@@ -3,6 +3,7 @@ import {
   datamodelDbmlComments,
   datamodelDbmlDefaults,
   datamodelDbmlManyToMany,
+  datamodelDbmlManyToManySelfRelation,
   datamodelDbmlRelations,
 } from './fixtures/dbml.datamodel';
 import { generateDMMF } from './utils/generateDMMF';
@@ -170,13 +171,13 @@ Table Book {
 }
 
 Table CategoryToPost {
-  categoryId Int [ref: > Category.id]
-  postId Int [ref: > Post.id]
+  categoriesId Int [ref: > Category.id]
+  postsId Int [ref: > Post.id]
 }
 
 Table AuthorToBook {
-  bookId Int [ref: > Book.id]
-  authorId Int [ref: > Author.id]
+  booksId Int [ref: > Book.id]
+  authorsId Int [ref: > Author.id]
 }`;
 
     const dbml = generateDBMLSchema(dmmf);
@@ -213,4 +214,25 @@ Table Book {
 
     expect(dbml).toEqual(expectedDbml);
   });
+
+  test('generating dbml schema with many-to-many self relationship', async () => {
+    const dmmf = await generateDMMF(datamodelDbmlManyToManySelfRelation);
+
+    const expectedDbml = `${autoGeneratedComment}
+
+Table User {
+  id Int [pk, increment]
+  followers User
+  following User
+}
+
+Table Followers {
+  followersId Int [ref: > User.id]
+  followingId Int [ref: > User.id]
+}`;
+
+    const dbml = generateDBMLSchema(dmmf);
+
+    expect(dbml).toEqual(expectedDbml);
+  });
 });

__tests__/fixtures/dbml.datamodel.ts

@@ -101,3 +101,11 @@ export const datamodelDbmlManyToMany = /* Prisma */ `
     authors Author[]
   }
 `;
+
+export const datamodelDbmlManyToManySelfRelation = /* Prisma */ `
+  model User {
+    id         Int        @id @default(autoincrement())
+    followers User[] @relation("Followers")
+    following User[] @relation("Followers")
+  }
+`;

src/generator/many-to-many-tables.ts

@@ -43,7 +43,7 @@ function generateJoinFields(field: DMMF.Field[], models: DMMF.Model[]): string {
 }
 
 function joinField(field: DMMF.Field, models: DMMF.Model[]): string {
-  return `  ${field.type.toLowerCase()}Id ${getJoinIdType(
+  return `  ${field.name.toLowerCase()}Id ${getJoinIdType(
     field,
     models
   )} [ref: > ${field.type}.${field.relationToFields![0]}]`;