How to allow circular relation with nullable: false? - typeorm

Question

I want to store who is the "creator" and "updater" of every record as a reference to the "User" table in my database. This applies to every table, including the "User" table itself. This is because it can happen that a record is created either by the user that is registering or by some other already existing user.
On the "User" table I have a DB trigger that fills the "creator" and "updater" fields to the same value as the newly generated "id" by default, hence I would like to use a NOT NULL constraint on my "creator" and "updater" column. Unfortunately, this results in the following error: "Circular relations detected: User -> User. To resolve this issue you need to set nullable: false somewhere in this dependency structure."
Is there a way for me to have a circular relation with a not null constraint using TypeORM?

Answer 1

I was actually able to make it work. I'm going to share my solution in case anyone is looking for an answer.
Before I was trying to auto generate the "created_by" column in the following way:
#ManyToOne(type => User, { onUpdate: 'CASCADE', onDelete: 'CASCADE', nullable: false })
#JoinColumn({ name: 'created_by' })
creator: User
All I had to do to make it work was to remove the nullable: false from there and move it to a new #Column field so that in total I would have:
#Column({ nullable: false })
created_by: number
#ManyToOne(type => User, { onUpdate: 'CASCADE', onDelete: 'CASCADE' })
#JoinColumn({ name: 'created_by' })
creator: User

Answer 2

I had a similar issue. I have a scenario where I have foreign key in the same table.
If I explain my scenario a bit more. I was working on storing conditional statements in an application.
condition#1 a > 4
condition#2 a + b < 0
Now I wanted to give user the ability to put a logical operator in b/w condition#1 and condition#2 . Let say user selected OR operator in b/w.
That would look like
(condition#1 OR condition#2)
Now comes the interesting part where I felt the need to have FK in the same. What if user wants to add another condition with OR operator before or after #1 and #2.
condition#3 OR (condition#1 OR condition#2)
So for storing these conditions I created relationships.
I stored 2 records for this scenario
1st for storing (condition#1 OR condition#2) and 2nd record for storing
condition#3 OR (condition#1 OR condition#2)
Now come to the point how I fixed it.
Previously it was something like :
export class ConditionLogicalOperator {
#PrimaryGeneratedColumn({
type: "int",
name: "ConditionLogicalOperatorID"
})
ConditionLogicalOperatorID: number;
#Column("int", {
nullable: false,
name: "LogicalOperatorID"
})
LogicalOperatorID: number;
#ManyToOne(() => ConditionLogicalOperator, (ConditionLogicalOperator: ConditionLogicalOperator) => ConditionLogicalOperator.conditionLogicalOperators)
#JoinColumn({ name: 'ConditionID1' })
conditionLogicalOperator1: ConditionLogicalOperator | null;
#ManyToOne(() => ConditionLogicalOperator, (ConditionLogicalOperator: ConditionLogicalOperator) => ConditionLogicalOperator.conditionLogicalOperators2)
#JoinColumn({ name: 'ConditionID2' })
conditionLogicalOperator2: ConditionLogicalOperator | null;
....
....
}
The trick was to add an empty object { } to Relationship. Please notice { } at the end of #ManyToOne line in each property. It worked for me.
export class ConditionLogicalOperator {
#PrimaryGeneratedColumn({
type: "int",
name: "ConditionLogicalOperatorID"
})
ConditionLogicalOperatorID: number;
#Column("int", {
nullable: false,
name: "LogicalOperatorID"
})
LogicalOperatorID: number;
#ManyToOne(() => ConditionLogicalOperator, (ConditionLogicalOperator: ConditionLogicalOperator) => ConditionLogicalOperator.conditionLogicalOperators, { })
#JoinColumn({ name: 'ConditionID1' })
conditionLogicalOperator1: ConditionLogicalOperator | null;
#ManyToOne(() => ConditionLogicalOperator, (ConditionLogicalOperator: ConditionLogicalOperator) => ConditionLogicalOperator.conditionLogicalOperators2, { })
#JoinColumn({ name: 'ConditionID2' })
conditionLogicalOperator2: ConditionLogicalOperator | null;
....
....
}