TypeORM why is my relationship column undefined? foreign-key is undefined - foreign-keys

Question

I just use TypeORM and find the relationship column is undefined
#Entity({name: 'person'})
export class Person {
#PrimaryGeneratedColumn('uuid')
id!: string;
#OneToOne( () => User)
#JoinColumn()
user!: User;
#Column({
type: "enum",
enum: PersonTitle,
default: PersonTitle.Blank
})
title?: string;
#Column({type: 'varchar', default: ''})
first_name!: string;
#Column('varchar')
last_name!: string;
#ManyToOne(() => Organization, org => org.people, { nullable: true})
belong_organization!: Organization;
and I also have Organization entity:
export class Organization {
#PrimaryGeneratedColumn('uuid')
id!: string;
...
}
when I use Repository like:
const db = await getDatabaseConnection()
const prep = db.getRepository<Person>('person')
presult = await prep.findOne({where: {id}})
console.log(result)
my result is:
Person {
id: '75c37eb9-1d88-4d0c-a927-1f9e3d909aef',
user: undefined,
title: 'Mr.',
first_name: 'ss',
last_name: 'ls',
belong_organization: undefined, // I just want to know why is undefined? even I can find in database the column
expertise: [],
introduction: 'input introduction',
COVID_19: false,
contact: undefined
}
the database table like:
"id" "title" "first_name" "last_name" "expertise" "COVID_19" "userId" "belongOrganizationId" "introduction"
"75c37eb9-1d88-4d0c-a927-1f9e3d909aef" "Mr." "test" "tester" "nothing" "0" "be426167-f471-4092-80dc-7aef67f13bac" "8fc50c9e-b598-483e-a00b-1d401c1b3d61" "input introduction"
I want to show organization id, how typeORM do it? Foreign-Key is present undefined?

Answer 1

You need to either lazy load the relation or you need to specify the relation in the find
Lazy:
#Entity({name: 'person'})
class Person {
...
#ManyToOne(() => Organization, org => org.people, { nullable: true})
belong_organization!: Organization;
...
}
...
async logOrganization() {
const db = await getDatabaseConnection()
const prep = db.getRepository<Person>('person')
presult = await prep.findOne({where: {id}})
console.log(await result.belong_organization)
}
Find
const prep = db.getRepository<Person>('person')
presult = await prep.findOne({
where: { id },
relations: ["belong_organization"]
})
You could also always do an eager load, but i'd advise against this since then it would always do the join when it fetches a person.
If you want to query the belong_organizationId you need to add its field to the person entity. This field is usual something like belongOrganizationId
That would make
#Entity({name: 'person'})
class Person {
...
#Column()
belongOrganizationId:number
#ManyToOne(() => Organization, org => org.people, { nullable: true})
belong_organization!: Organization;
...
}
This would make it possible to query for its id too.
You could also query it more directly but this leaves you with some pretty ugly and unmaintainable code:
const findOptions: {
where :{
id,
'belong_organization.id': belong_organizationId
}
}