Gorm bug: FirstOrCreate's does not return Assign result into struct

GORM Playground Link

https://github.com/go-gorm/playground/pull/829

Description

with a valid record at age 19, i would expect adding 1 to return 20 into the resultant struct with

DB.Where("name = ?", "jinzhu").Assign("age", gorm.Expr("age + ?", 1)).FirstOrCreate(&update20)

unfortunately this does not happen compared to if I used an absolute value .Assign("age", 20)

thus the gorm.Expr breaks the handlng

luckily you can throw a returning clause to restore expected behaviour

DB.Clauses(clause.Returning{}).Where("name = ?", "jinzhu").Assign("age", gorm.Expr("age + ?", 5)).FirstOrCreate(&update2)

this should be fixed; documentation can solve the issue as a stop gap

GORM_DIALECT=postgres go test -v
2025/09/17 17:34:49 testing postgres...
=== RUN   TestGORM

2025/09/17 17:34:49 /Users/allen/dev/playground/main_test.go:17
[0.484ms] [rows:0] SELECT * FROM "users" WHERE "users"."deleted_at" IS NULL ORDER BY "users"."id" LIMIT 1

2025/09/17 17:34:49 /Users/allen/dev/playground/main_test.go:17
[0.929ms] [rows:1] INSERT INTO "users" ("created_at","updated_at","deleted_at","name","age","birthday","company_id","manager_id","active") VALUES ('2025-09-17 17:34:49.47','2025-09-17 17:34:49.47',NULL,'jinzhu',18,NULL,NULL,NULL,false) RETURNING "id"
    main_test.go:23: Success, got user name: jinzhu, expected: jinzhu

2025/09/17 17:34:49 /Users/allen/dev/playground/main_test.go:30
[0.361ms] [rows:1] SELECT * FROM "users" WHERE name = 'jinzhu' AND "users"."deleted_at" IS NULL ORDER BY "users"."id" LIMIT 1

2025/09/17 17:34:49 /Users/allen/dev/playground/main_test.go:30
[0.695ms] [rows:1] UPDATE "users" SET "age"=19,"updated_at"='2025-09-17 17:34:49.471' WHERE name = 'jinzhu' AND "users"."deleted_at" IS NULL AND "id" = 1
    main_test.go:36: Success, got user age: 19, expected: 19

2025/09/17 17:34:49 /Users/allen/dev/playground/main_test.go:43
[0.186ms] [rows:1] SELECT * FROM "users" WHERE name = 'jinzhu' AND "users"."deleted_at" IS NULL ORDER BY "users"."id" LIMIT 1

2025/09/17 17:34:49 /Users/allen/dev/playground/main_test.go:43
[0.680ms] [rows:1] UPDATE "users" SET "age"=age + 1,"updated_at"='2025-09-17 17:34:49.472' WHERE name = 'jinzhu' AND "users"."deleted_at" IS NULL AND "id" = 1
    main_test.go:47: Failed, got user age: 19, expected: 20

2025/09/17 17:34:49 /Users/allen/dev/playground/main_test.go:55
[0.188ms] [rows:1] SELECT * FROM "users" WHERE name = 'jinzhu' AND "users"."deleted_at" IS NULL ORDER BY "users"."id" LIMIT 1
    main_test.go:61: Success, got user 1 with age 20

2025/09/17 17:34:49 /Users/allen/dev/playground/main_test.go:67
[0.181ms] [rows:1] SELECT * FROM "users" WHERE name = 'jinzhu' AND "users"."deleted_at" IS NULL ORDER BY "users"."id" LIMIT 1

2025/09/17 17:34:49 /Users/allen/dev/playground/main_test.go:67
[0.723ms] [rows:1] UPDATE "users" SET "age"=age + 5,"updated_at"='2025-09-17 17:34:49.473' WHERE name = 'jinzhu' AND "users"."deleted_at" IS NULL AND "id" = 1 RETURNING *
    main_test.go:73: Success, got user age: 25, expected: 25
--- FAIL: TestGORM (0.00s)
FAIL