fix(rest): multiple relation id filter values are not properly split

fixes #2061

Author: ymc9

packages/server/src/api/rest/index.ts

@@ -1750,7 +1750,12 @@ class RequestHandler extends APIHandlerBase {
                         : this.makePrismaIdFilter(info.idFields, value, false);
                 return { some: filterValue };
             } else {
-                return { is: this.makePrismaIdFilter(info.idFields, value, false) };
+                const values = value.split(',').filter((i) => i);
+                if (values.length > 1) {
+                    return { OR: values.map((v) => this.makePrismaIdFilter(info.idFields, v, false)) };
+                } else {
+                    return { is: this.makePrismaIdFilter(info.idFields, value, false) };
+                }
             }
         } else {
             const coerced = this.coerce(fieldInfo.type, value);

packages/server/tests/api/rest.test.ts

@@ -664,6 +664,15 @@ describe('REST server tests', () => {
                     expect(r.body.data).toHaveLength(1);
                     expect(r.body.data[0]).toMatchObject({ id: 1 });
 
+                    // relation filter with multiple values
+                    r = await handler({
+                        method: 'get',
+                        path: '/post',
+                        query: { ['filter[author]']: 'user1,user2' },
+                        prisma,
+                    });
+                    expect(r.body.data).toHaveLength(2);
+
                     // invalid filter field
                     r = await handler({
                         method: 'get',