无法查询属性为空的DynamoDB记录

var AWS = require("aws-sdk");
var dynamodb = new AWS.DynamoDB();

var params = {
    TableName: "YourTableName",
    FilterExpression: "attribute_not_exists(AttributeName) OR AttributeName = :nullValue",
    ExpressionAttributeValues: {
        ":nullValue": { "NULL": true }
    }
};

dynamodb.scan(params, function(err, data) {
    if (err) {
        console.log("Error", err);
    } else {
        console.log("Success", data.Items);
    }
});

var AWS = require("aws-sdk");
var dynamodb = new AWS.DynamoDB();

var params = {
    TableName: "YourTableName",
    KeyConditionExpression: "PartitionKey = :pkValue",
    FilterExpression: "attribute_not_exists(AttributeName) OR AttributeName = :nullValue",
    ExpressionAttributeValues: {
        ":pkValue": { "S": "PartitionKeyValue" },
        ":nullValue": { "NULL": true }
    }
};

dynamodb.query(params, function(err, data) {
    if (err) {
        console.log("Error", err);
    } else {
        console.log("Success", data.Items);
    }
});