Generating Migration on ManyToOne/OneToMany + Primary enum column results in missing enum type in migration output

[koheiio]

Issue Description

Expected Behavior

Generating a migration between two tables, one having a enum primary column and a one-to-many / many-to-one relation between them should generate valid SQL, with corrrect enum typing on the table B column statements that reference the primary column of table A

Actual Behavior

The migration contains column statements that reference a "NULL" type enum. It should be ('msGraph', 'atlassian') etc

query: ALTER TABLE `access_event` ADD `employeeProvider` enum NULL
query failed: ALTER TABLE `access_event` ADD `employeeProvider` enum NULL
error: Error: ER_PARSE_ERROR: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'NOT NULL' at line 1

Steps to Reproduce

1. Create a simple entity setup like below
2. Generate a migration
3. Run said migration

enum Providers { 
  MS_GRAPH = 'msGraph'
  ATLASSIAN = 'atlassian'
}

@Entity()
export class Employee extends BaseEntity {
  @PrimaryColumn({ type: 'enum', enum: Providers })
  provider!: Providers
  
  @OneToMany(() => AccessEvent, (accessEvent) => accessEvent.employee)
  accessEvents!: AccessEvent[]
}

@Entity()
export class AccessEvent extends BaseEntity {
  @PrimaryColumn({ type: 'varchar', length: 128 })
  id!: string

  @ManyToOne(() => Employee, (employee) => employee.accessEvents)
  employee!: Employee
}

Generating a migration from this results in it creating a line like this in the migration:

`ALTER TABLE `access_event` ADD `employeeProvider` enum NULL`

It somehow is unable to retrieve the enum values. If I change Employee's primary column to @PrimaryColumn({ type: 'varchar', length: 128 }) it generates a migration with the correct typing, but not when I use enum.

My Environment

I'm running this in my Next.js application

Dependency	Version
Operating System	Ubuntu 20.04
Node.js version	v14.13.0`
Typescript version	v4.0.5
TypeORM version	v0.2.30

Additional Context

The enum is actually stored elsewhere, and verified to be valid. The location has no effect on it

Relevant Database Driver(s)

• aurora-data-api
• aurora-data-api-pg
• better-sqlite3
• cockroachdb
• cordova
• expo
• mongodb
• mysql
• nativescript
• oracle
• postgres
• react-native
• sap
• sqlite
• sqlite-abstract
• sqljs
• sqlserver

Are you willing to resolve this issue by submitting a Pull Request?

• Yes, I have the time, and I know how to start.
• Yes, I have the time, but I don't know how to start. I would need guidance.
• No, I don't have the time, although I believe I could do it if I had the time...
• No, I don't have the time and I wouldn't even know how to start.

Give me guidance! I might be able to do if the problem is identified

[koheiio]

Same issue here #6047