Params:

参数：

 {
        "TableName": "xxxxxxx",
        "Key": {
            "userId": {
                "S": "test"
            }
        },
        "UpdateExpression": "SET sent.#assignmentType = :newHomeworks",
        "ExpressionAttributeNames": {
            "#assignmentType": "books"
        },
        "ExpressionAttributeValues": {
            ":newHomeworks": [
                {
                    "M": {
                        "homeworkId": {
                            "S": "homework"
                        },
                        "userIds": {
                            "L": [
                                {
                                    "S": "test1"
                                },
                                {
                                    "S": "test2"
                                }
                            ]
                        }
                    }
                }
            ]
        },
        "ReturnValues": "UPDATED_NEW"
    }

do you know why I'm getting this error? It is when I'm trying to update the item like that.
newHomeworks ormat is wrong? it should be an array of objects.Thank you!

你知道我为什么会犯这个错误吗？这是当我试图像那样更新项目时。newHomeworks格式错误？它应该是一个对象数组。非常感谢。

I have inserted only the broken code,It's breaking after the "Update params" log, I tried to send the params in many ways but I cannot find an explanation, I don't know why I get this error.
I don't think it's something wrong in updateHomeworkTable because it's working in other cases, only here it is breaking.
code:

我只插入了损坏的代码，在“更新params”日志之后它就坏了，我试图通过多种方式发送params，但我找不到解释，我不知道为什么我会出现这个错误。我不认为updateHomeworkTable有什么问题，因为它在其他情况下也能工作，只是在这里它坏了。代码：

async assignedHomework(
    userId: string,
    studentIds: any,
    homework: any,
    assignmentType: string
  ) {
    const userHomeworks = await this.reader.getUserFromDb(userId);
    if (userHomeworks?.sent) {
      if (userHomeworks.sent[assignmentType]) {
        for (const homeworkObj of userHomeworks.sent[assignmentType]) {
          if (homeworkObj.homeworkId === homework) {
            homeworkObj.userIds = Array.from(
              new Set([...homeworkObj.userIds, ...studentIds])
            );

            const updateExpression = "SET sent.#assignmentType = :newHomeworks";

            // Define attribute names and values
            const expressionAttributeNames = {
              "#assignmentType": assignmentType,
            };
            this.logger.debug("parameters", userHomeworks.sent[assignmentType]);

            // AICI NEW HOMEWORKS NU ARE TREBUII SA FIE ALTFEL?
            const expressionAttributeValues = {
              ":newHomeworks": marshall(userHomeworks.sent[assignmentType]),
            };
            this.logger.debug(
              "parameters after update",
              marshall(userHomeworks.sent[assignmentType])
            );
            return await updateHomeworkTable(
              this.tableName,
              userId.toString(),
              updateExpression,
              expressionAttributeNames,
              expressionAttributeValues,
              this.instance,
              this.logger
            );
          }
        }
        const updateExpression =
          "SET sent.#assignmentType = list_append(if_not_exists(sent.#assignmentType, :emptyList), :newHomework)";

        // Define attribute names and values
        const expressionAttributeNames = {
          "#assignmentType": assignmentType,
        };

        const expressionAttributeValues = {
          ":newHomework": {
            L: [
              {
                M: {
                  homeworkId: { S: homework },
                  userIds: { L: studentIds.map((id: string) => ({ S: id })) },
                },
              },
            ],
          },
          ":emptyList": { L: [] },
        };
        return await updateHomeworkTable(
          this.tableName,
          userId.toString(),
          updateExpression,
          expressionAttributeNames,
          expressionAttributeValues,
          this.instance,
          this.logger
        );
      } else {
  }
}
const updateHomeworkTable = async (
  tableName: string,
  userId: string,
  updateExpression: string,
  expressionAttributeNames: any,
  expressionAttributeValues: any,
  instance: any,
  logger: any
) => {
  // Create UpdateItem command input
  const params: UpdateItemCommandInput = {
    TableName: tableName,
    Key: {
      userId: { S: userId },
    },
    UpdateExpression: updateExpression,
    ExpressionAttributeNames: expressionAttributeNames,
    ExpressionAttributeValues: expressionAttributeValues,
    ReturnValues: "UPDATED_NEW",
  };

  logger.debug("Update params", params);
  await instance.send(new UpdateItemCommand(params));
  logger.debug("Update finished");
};

Update...
it shouldn't be something here ?
Like ":newHomeworks":{L:[]}?

使现代化这不应该是什么东西吗？像“：newHomeworks”：｛L:[]｝？