GraphQL Ariadne python Getting“无法为不可为null的字段返回null”，尽管值不是null

Question

我得到了关于为success字段返回null的错误信息，但它包含在我的返回负载中。 返回有效载荷如下所示

{'success': True, 'GeneratedKeywords': [{'id': 1, 'file_id': 1, 'keywords': 'keyword', 'generated_date': '11-01-2021'}, {'id': 2, 'file_id': 1, 'keywords': 'keyword', 'generated_date': '11-01-2021'}]}

模式

type DocumentKeywords {
    id: ID!
    file_id: Int!
    keywords: String!
    generated_date: String!
}
type GetAllKeyowrdsResult {
    success: Boolean
    errors: [String]
    GeneratedKeywords: [DocumentKeywords]
}
type Query {
    GetAllKeywords: [GetAllKeyowrdsResult]
}

解析器代码

def resolve_AllKeywords(obj, info):
    try:
        #print(GeneratedKeywords.query.all(), file=sys.stderr)
        #GKs = [genKeys.to_dict() for genKeys in GeneratedKeywords.query.all()]
        GKs = []
        for genKeys in GeneratedKeywords.query.all():
            print(genKeys, file=sys.stderr)
            GKs.append(genKeys.to_dict())
        print(GKs, file=sys.stderr)
        payload = {
            "success": True,
            "GeneratedKeywords": GKs
        }
        print(payload, file=sys.stderr)
    except Exception as error:
        payload = {
            "success": False,
            "errors": [str(error)]
        }
    return payload
    ```