TypeError:在Django数据迁移期间，Decimal类型的对象不可JSON序列化

我在模型中添加了一个

postgres

JsonField

，并为其创建了

数据迁移

new_column=pg_fields.JSONField（默认值=dict，编码器=DjangoJSONEncoder）

相同的逻辑用于未来数据（在模型的
save（）
中）和历史数据（数据迁移）

这是我试图保存的数据格式

data = {
        'premium': obj.amount * obj.persons,
    }
proposal.new_column = data
proposal.save()

这里，
obj
是其他一些模型的实例，
amount
是该模型的
DecimalField

该逻辑在model类的
save（）
方法中运行良好。
但是在运行数据迁移时，我遇到了这个错误
TypeError:Decimal类型的对象不可JSON序列化

Stacktrace

Traceback (most recent call last):
  File "./manage.py", line 21, in <module>
    execute_from_command_line(sys.argv)
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/core/management/__init__.py", line 381, in execute_from_command_line
    utility.execute()
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/core/management/__init__.py", line 375, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/core/management/base.py", line 323, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/core/management/base.py", line 364, in execute
    output = self.handle(*args, **options)
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/core/management/base.py", line 83, in wrapped
    res = handle_func(*args, **kwargs)
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/core/management/commands/migrate.py", line 234, in handle
    fake_initial=fake_initial,
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/db/migrations/executor.py", line 117, in migrate
    state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/db/migrations/executor.py", line 147, in _migrate_all_forwards
    state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/db/migrations/executor.py", line 245, in apply_migration
    state = migration.apply(state, schema_editor)
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/db/migrations/migration.py", line 124, in apply
    operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/db/migrations/operations/special.py", line 190, in database_forwards
    self.code(from_state.apps, schema_editor)
  File "/home/simarpreet/Aegon/jarvis/insurance/travel/proposal/migrations/0006_auto_20191111_1943.py", line 34, in repopulate_slab_in_proposals
    proposal.save()
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/db/models/base.py", line 741, in save
    force_update=force_update, update_fields=update_fields)
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/db/models/base.py", line 779, in save_base
    force_update, using, update_fields,
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/db/models/base.py", line 851, in _save_table
    forced_update)
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/db/models/base.py", line 900, in _do_update
    return filtered._update(values) > 0
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/db/models/query.py", line 760, in _update
    return query.get_compiler(self.db).execute_sql(CURSOR)
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/db/models/sql/compiler.py", line 1429, in execute_sql
    cursor = super().execute_sql(result_type)
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/db/models/sql/compiler.py", line 1100, in execute_sql
    cursor.execute(sql, params)
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/db/backends/utils.py", line 99, in execute
    return super().execute(sql, params)
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/db/backends/utils.py", line 67, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/db/backends/utils.py", line 76, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/psycopg2/_json.py", line 78, in getquoted
    s = self.dumps(self.adapted)
  File "/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/contrib/postgres/fields/jsonb.py", line 27, in dumps
    return json.dumps(obj, **options)
  File "/usr/lib/python3.7/json/__init__.py", line 231, in dumps
    return _default_encoder.encode(obj)
  File "/usr/lib/python3.7/json/encoder.py", line 199, in encode
    chunks = self.iterencode(o, _one_shot=True)
  File "/usr/lib/python3.7/json/encoder.py", line 257, in iterencode
    return _iterencode(o, 0)
  File "/usr/lib/python3.7/json/encoder.py", line 179, in default
    raise TypeError(f'Object of type {o.__class__.__name__} '
TypeError: Object of type Decimal is not JSON serializable

回溯（最近一次呼叫最后一次）：
文件“/manage.py”，第21行，在
从命令行（sys.argv）执行命令
文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/django/core/management/_init__.py”，第381行，从命令行执行
utility.execute（）
文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/django/core/management/_init__.py”，执行中第375行
self.fetch_命令（子命令）。从_argv（self.argv）运行_
文件“/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/core/management/base.py”，第323行，运行于
self.execute（*args，**cmd_选项）
文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/django/core/management/base.py”，第364行，在execute中
输出=self.handle（*args，**选项）
文件“/home/simarpreet/Envs/j/lib/python3.7/site-packages/django/core/management/base.py”，第83行，包装
res=句柄函数（*args，**kwargs）
handle中的文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/django/core/management/commands/migrate.py”，第234行
假首字母=假首字母，
文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/django/db/migrations/executor.py”，migrate中的第117行
状态=self.\u迁移\u所有\u转发（状态，计划，完整计划，假=假，假首字母=假首字母）
文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/django/db/migrations/executor.py”，第147行，全部向前迁移
state=self.apply\u迁移（state，migration，false=false，false\u initial=false\u initial）
文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/django/db/migrations/executor.py”，第245行，在apply_migration中
state=migration.apply（状态，模式编辑器）
文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/django/db/migrations/migration.py”，第124行，在apply中
操作。数据库转发（self.app\u标签、模式编辑器、旧状态、项目状态）
数据库中的文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/django/db/migrations/operations/special.py”，第190行
self.code（来自_state.apps，模式编辑器）
文件“/home/simarpreet/Aegon/jarvis/insurance/travel/proposal/migrations/0006_auto_20191111_1943.py”，第34行，在重新填充板中
建议保存（）
文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/django/db/models/base.py”，第741行，保存
强制更新=强制更新，更新字段=更新字段）
文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/django/db/models/base.py”，第779行，在save_base中
强制更新，使用，更新字段，
文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/django/db/models/base.py”，第851行，在保存表格中
强制更新）
文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/django/db/models/base.py”，第900行，在更新中
返回已筛选的。\u更新（值）>0
文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/django/db/models/query.py”，第760行，在更新中
返回query.get_编译器（self.db）。执行_sql（游标）
文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/django/db/models/sql/compiler.py”，第1429行，在execute_sql中
cursor=super（）。执行sql（结果类型）
文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/django/db/models/sql/compiler.py”，第1100行，在execute_sql中
cursor.execute（sql，params）
文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/django/db/backends/utils.py”，执行中的第99行
return super（）.execute（sql，params）
文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/django/db/backends/utils.py”，执行中第67行
返回self.\u使用包装器执行（sql，params，many=False，executor=self.\u execute）
文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/django/db/backends/utils.py”，第76行，使用包装器执行
返回执行器（sql、参数、多个、上下文）
文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/django/db/backends/utils.py”，第84行，在
返回self.cursor.execute（sql，params）
文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/psycopg2/_json.py”，第78行，在getquoted中
s=自转储（自适应）
文件“/home/simarpreet/Envs/j/lib/python3.7/site packages/django/contrib/postgres/fields/jsonb.py”，第27行，转储
返回json.dumps（obj，**选项）
文件“/usr/lib/python3.7/json/_init__.py”，第231行，转储
返回默认编码器编码（obj）
文件“/usr/lib/python3.7/json/encoder.py”，第199行，在encode中
chunks=self.iterencode（o，\u one\u shot=True）
iterencode中的文件“/usr/lib/python3.7/json/encoder.py”，第257行
返回_iterencode（o，0）
默认情况下，文件“/usr/lib/python3.7/json/encoder.py”第179行
raise TypeError（f'类型为{o.\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\的对象'
TypeError:Decimal类型的对象不可JSON序列化

但是根据Django data migration（）的文档，Django可以序列化decimal.decimal值。

有人能告诉我为什么会出现此错误吗？
我之所以会遇到此问题，是因为我在添加编码器后忘记运行迁移

new_column=pg_fields.JSONField（de