async_model_to_dict

因为源码有点长，这里只截取重要部分

from peewee import *
from peewee import Alias
import peewee_async
from Main.settings import database
objects = peewee_async.Manager(database)
database.set_allow_sync(False)　 # 异步化

_clone_set = lambda s: set(s) if s else set()


async def async_model_to_dict(model, recurse=True, backrefs=False, only=None,
                  exclude=None, seen=None, extra_attrs=None,
                  fields_from_query=None, max_depth=None):

    max_depth = -1 if max_depth is None else max_depth
    if max_depth == 0:
        recurse = False

    only = _clone_set(only)
    extra_attrs = _clone_set(extra_attrs)

    if fields_from_query is not None:
        for item in fields_from_query._returning:
            if isinstance(item, Field):
                only.add(item)
            elif isinstance(item, Alias):
                extra_attrs.add(item._alias)

    data = {}
    exclude = _clone_set(exclude)   # 记录所有外键
    seen = _clone_set(seen)
    exclude |= seen
    model_class = type(model)
    
###########################################
    此for循环取数据
    for field in model._meta.sorted_fields:
        if field in exclude or (only and (field not in only)):
            continue

        field_data = model.__data__.get(field.name)
        if isinstance(field, ForeignKeyField) and recurse:
            if field_data:
                seen.add(field)
            ################################################
                修改：异步化之后因为关联查询问题，field.name虽然有，但是取不到
                这里直接return data的原因是这里只取一层外键，不再往上取二层
                try:
                    rel_obj = getattr(model, field.name)
                except:
                    return data

                field_data = await async_model_to_dict(
                    rel_obj,
                    recurse=recurse,
                    backrefs=backrefs,
                    only=only,
                    exclude=exclude,
                    seen=seen,
                    max_depth=max_depth - 1)
            else:
                field_data = None

        data[field.name] = field_data

    #################################
    这里是递归反向查询
    if backrefs and recurse:
        for foreign_key, rel_model in model._meta.backrefs.items():
            if foreign_key.backref == '+': continue
            descriptor = getattr(model_class, foreign_key.backref)
            if descriptor in exclude or foreign_key in exclude:
                continue
            if only and (descriptor not in only) and (foreign_key not in only):
                continue

            accum = []
            exclude.add(foreign_key)
            related_query = getattr(model, foreign_key.backref)

            try:
                #########################################
                为什么这里从原来的  for rel_obj in related_query:
                加上了 objects.execute，因为同步的模式使用for循环就可以
                使query对象执行，而异步的模式会出错，因此要手动execute
 
                related_objects = await objects.execute(related_query)
                for rel_obj in related_objects:
                    accum.append(await async_model_to_dict(
                        rel_obj,
                        recurse=recurse,
                        backrefs=backrefs,
                        only=only,
                        exclude=exclude,
                        max_depth=max_depth - 1))
                data[foreign_key.backref] = accum

            except AssertionError:
                recurse = False

    return data

https://www.jianshu.com/p/dea99042f97f