Fix 3120

[Saniol]

Description of change

Fixes #3120 by adding a new relation option "createForeignKeyConstraints". That's updated version of #7112 PR by @alpharder, with fixes suggested by @nebkat and updated tests & docs.

Pull-Request Checklist

• Code is up-to-date with the master branch
• npm run lint passes with this change
• npm run test passes with this change (there are some linter errors not related to those changes - mainly in exxisting test cases)
• This pull request links relevant issues as Fixes #0000
• There are new or updated unit tests validating the change
• Documentation has been updated to reflect this change
• The new commits follow conventions explained in CONTRIBUTING.md

[nebkat]

Shouldn't joinColumns and inverseJoinColumns still be set here, even if there are no foreign keys?

typeorm/src/metadata/RelationMetadata.ts

Lines 490 to 500 in c4a36da

	registerForeignKeys(...foreignKeys: ForeignKeyMetadata[]) {
	this.foreignKeys.push(...foreignKeys);
	this.joinColumns = this.foreignKeys[0] ? this.foreignKeys[0].columns : [];
	this.inverseJoinColumns = this.foreignKeys[1] ? this.foreignKeys[1].columns : [];
	this.isOwning = this.isManyToOne || ((this.isManyToMany || this.isOneToOne) && this.joinColumns.length > 0);
	this.isOneToOneOwner = this.isOneToOne && this.isOwning;
	this.isOneToOneNotOwner = this.isOneToOne && !this.isOwning;
	this.isManyToManyOwner = this.isManyToMany && this.isOwning;
	this.isManyToManyNotOwner = this.isManyToMany && !this.isOwning;
	this.isWithJoinColumn = this.isManyToOne || this.isOneToOneOwner;
	}

If so, last paragraph of my comment describes the necessary changes.

[Saniol]

@nebkat you're right, I missed that... PR updated

[nebkat]

Looks good now!

[nebkat]

Maybe just rename this field to joinColumns?

[Saniol]

I thought about it - and I'm worried that it might be confusing, as this function already takes joinColumns (JoinColumnMetadataArgs type) as argument, but in the result columns type is ColumnMetadata[] - so I've decided to follow same naming as for types. Please let me know, if you have another idea how to resolve that naming conflict

[pleerock]

what do you think if we just call it constraint: false ?

[nebkat]

Could there be confusion with unique constraints? I think there is some driver that requires a unique on foreign keys.

[pleerock]

Thank you for contribution! 🎉