relationship

error: 

*** There was an issue. Reason: there is no unique constraint matching given keys for referenced table "_video". Table: null Column: null

_hashtag:

import 'package:vw_serv/model/hashtagging.dart';
import 'package:vw_serv/vw_serv.dart';

class HashTag extends ManagedObject<_HashTag> implements _HashTag {}

class _HashTag {
  @Column(indexed: true, omitByDefault: true, autoincrement: true)
  int id;

  @Column(primaryKey: true)
  String identifier;

  @Column()
  DateTime createdAt;

  ManagedSet<HashTagging> hashtaggings;

  @Column(nullable: false)
  String tag;
}


_video:

import 'package:vw_serv/model/hashtagging.dart';
import 'package:vw_serv/model/like.dart';
import 'package:vw_serv/model/share.dart';
import 'package:vw_serv/model/user.dart';
import 'package:vw_serv/vw_serv.dart';

class Video extends ManagedObject<_Video> implements _Video {
  @Serialize(output: false)
  String userIdentifier;

  @Serialize(output: false)
  List<String> hashes;

  @Serialize(output: false)
  List<String> friends;

  @Serialize(output: false)
  List<String> shareTo;
}

class _Video {
  @Column(indexed: true, omitByDefault: true, autoincrement: true)
  int id;

  @Column(primaryKey: true)
  String identifier;

  @Column()
  DateTime createdAt;

  @Column()
  String createdBy;

  @Relate(#videos)
  User creator;

  ManagedSet<HashTagging> hashtaggings;

  ManagedSet<Like> likes;

  ManagedSet<Share> shares;

  @Column()
  String title;

  @Column(nullable: true)
  String content;

  @Column(defaultValue: "true")
  bool public;

  @Column(nullable: true)
  double latitude;

  @Column(nullable: true)
  double longitude;

  @Column()
  double aspectRatio;

  @Column()
  String appliedFilter;

  @Column()
  String type;

  @Column(nullable: true)
  int startTime;

  @Column()
  String downloadUrl;

  @Column()
  String thumbUrl;
}


_hashTag migration:

import 'dart:async';
import 'package:aqueduct/aqueduct.dart';

class Migration9 extends Migration {
  @override
  Future upgrade() async {
    database.createTable(SchemaTable("_HashTag", [
      SchemaColumn("id", ManagedPropertyType.bigInteger,
          isPrimaryKey: false,
          autoincrement: true,
          isIndexed: true,
          isNullable: false,
          isUnique: false),
      SchemaColumn("identifier", ManagedPropertyType.string,
          isPrimaryKey: true,
          autoincrement: false,
          isIndexed: true,
          isNullable: true,
          isUnique: false),
      SchemaColumn("tag", ManagedPropertyType.string,
          isPrimaryKey: false,
          autoincrement: false,
          isIndexed: false,
          isNullable: false,
          isUnique: false)
    ]));
    database.addColumn(
        "_HashTag",
        SchemaColumn.relationship("video", ManagedPropertyType.bigInteger,
            relatedTableName: "_Video",
            relatedColumnName: "id",
            rule: DeleteRule.nullify,
            isNullable: true,
            isUnique: false));
  }

  @override
  Future downgrade() async {}

  @override
  Future seed() async {}
}