DynamoDB查询报TypeError：无法读取undefined的'0'属性，求排查

我有一个名为AllowListedItems的DynamoDB表，包含Id、name和ignoreNoTraffic字段，且在name字段上创建了名为name-index的GSI。尝试通过name查询ignoreNoTraffic的值时，AWS SDK V3的TypeScript代码报错，但AWS SDK V2的JavaScript代码可正常执行。

AWS SDK V3 TypeScript代码 #

业务逻辑代码 #

import { DynamoDB, GetItemCommand, ScanCommand, QueryCommand } from "@aws-sdk/client-dynamodb";
import { unmarshall } from "@aws-sdk/util-dynamodb";

private async getIgnoreNoTraffic(): Promise<boolean> {
    const params = {
        TableName: Tables.ALLOW_LISTED_ITEMS,
        IndexName: "name-index",
        KeyConditionExpression: "#nameAttr = :nameValue",
        ExpressionAttributeNames: {
            "#nameAttr": "name" 
        },
        ExpressionAttributeValues: {
            ":nameValue": this.name,
        },
    };

    try {
        const items = await dynamodbUtils.queryValuesFromDB(params);

        if (items.length > 0) {
            const item = items[0];
            console.log("Received item:", item);

            if (item. ignoreNoTraffic !== undefined) {
                return item. ignoreNoTraffic.BOOL || false;  
            } else {
                return false;
            }
        } else {
            console.log("Item could not be fetched from the table using name");
            return false;
        }
    } catch (error) {
        console.error("Error fetching ignoreNoTraffic by name:", error);
        throw error;
    }
}

DynamoDB工具函数 #

export async function queryValuesFromDB(params: any) {
console.log("Querying DynamoDB with params2:", JSON.stringify(params, null, 2));

try {
    const data = await client.send(new QueryCommand(params));

    if (!data) {
        console.error("DynamoDB returned undefined or null data.");
        throw new Error("DynamoDB returned undefined or null data.");
    }

    console.log("Received raw data from DynamoDB:", JSON.stringify(data, null, 2));

    if (!data.Items) {
        console.log("Items field is missing from the data.");
        throw new Error("DynamoDB response does not contain 'Items'.");
    }

    if (data.Items.length > 0) {
        console.log("Successfully retrieved items:", data.Items);
        return data.Items; // Directly return the items as JSON
    } else {
        console.log("No items found for the query.");
        return [];
    }
} catch (error) {
    console.error("Error executing DynamoDB query:", error);

    if (error instanceof Error) {
        console.error("Error message:", error.message);
        throw new Error(`DynamoDB Query Error: ${error.message}`);
    } else {
        console.error("Unknown error occurred:", JSON.stringify(error));
        throw new Error("An unknown error occurred during DynamoDB query.");
    }
}

错误信息 #

ERROR   Error while sending query command to DynamoDB: TypeError: Cannot read properties of undefined (reading '0')

日志信息 #

INFO    Querying DynamoDB with params3: 
{
"TableName": "AllowListedItems",
"IndexName": "name-index",
"KeyConditionExpression": "#nameAttr = :nameValue",
"ExpressionAttributeNames": {
    "#nameAttr": "name"
},
"ExpressionAttributeValues": {
    ":nameValue": "development"
}
}

可正常运行的AWS SDK V2 JavaScript代码 #

const AWS = require('aws-sdk');
const dynamodb = new AWS.DynamoDB();
const docClient = new AWS.DynamoDB.DocumentClient();

async function queryValuesFromDB(params) {
    console.log("Querying DynamoDB with params:", JSON.stringify(params, null, 2));

    try {
        const data = await docClient.query(params).promise();
        console.log("Received raw data from DynamoDB:", JSON.stringify(data, null, 2));

        if (data && data.Items && data.Items.length > 0) {
            console.log("Successfully retrieved items:", data.Items);
            return data.Items; 
        } else {
            console.log("No items found for the query.");
            return [];
        }
    } catch (error) {
        console.error("Error executing DynamoDB query:", error.message || error);
        throw new Error(`DynamoDB Query Error: ${error.message || error}`);
    }
}

async function getIgnoreNoTraffic(name) {
    const params = {
        TableName: 'AllowListedItems', 
        IndexName: 'name-index', 
        KeyConditionExpression: "#nameAttr = :nameValue",
        ExpressionAttributeNames: {
            "#nameAttr": "name" 
        },
        ExpressionAttributeValues: {
            ":nameValue": name, 
        },
    };

    try {
        const items = await queryValuesFromDB(params);
        if (items.length > 0) {
            const item = items[0];
            if (item. ignoreNoTraffic !== undefined) {
                return item. ignoreNoTraffic;
            } else {
                return false;
            }
        } else {
            console.log("Item could not be fetched from the table using name");
            return false;
        }
    } catch (error) {
        console.error("Error fetching ignoreNoTraffic by name:", error);
        throw error;
    }
}

exports.handler = async (event) => {
    const name = event.name || "test-name"; 
    try {
        const ignoreNoTraffic = await getIgnoreNoTraffic(name);
        console.log("Ignore result:", ignoreNoTraffic);
        return {
            statusCode: 200,
            body: JSON.stringify({
                message: "Success",
                ignoreNoTraffic: ignoreNoTraffic
            }),
        };
    } catch (error) {
        return {
            statusCode: 500,
            body: JSON.stringify({
                message: "Error",
                error: error.message,
            }),
        };
    }
};

1. SDK数据格式不兼容：V3使用的是低阶DynamoDB客户端，要求ExpressionAttributeValues必须传入带类型标识的DynamoDB原生格式（如{ S: "value" }），但你直接传入了字符串，导致查询失败，工具函数返回的items异常。而V2使用的DocumentClient会自动处理格式转换，所以可正常运行。
2. 代码语法错误：业务代码中item. ignoreNoTraffic的点后多了空格，实际访问的是带前导空格的属性名，与表中实际字段ignoreNoTraffic不匹配，导致读取属性时返回undefined，进而触发读取.BOOL的错误。
3. GSI投影属性缺失（潜在风险）：如果name-index的投影属性未包含ignoreNoTraffic，即使查询成功，也不会返回该字段，同样会导致属性读取失败。

方案1：改用DynamoDBDocumentClient（推荐） #

使用V3高阶客户端DynamoDBDocumentClient，自动处理数据格式转换，和V2的DocumentClient逻辑一致：

修改工具函数 #

import { DynamoDBDocumentClient, QueryCommand } from "@aws-sdk/lib-dynamodb";
import { DynamoDB } from "@aws-sdk/client-dynamodb";

const client = new DynamoDB({});
const docClient = DynamoDBDocumentClient.from(client);

export async function queryValuesFromDB(params: any) {
    console.log("Querying DynamoDB with params:", JSON.stringify(params, null, 2));

    try {
        const data = await docClient.send(new QueryCommand(params));
        return data.Items || [];
    } catch (error) {
        console.error("Error executing DynamoDB query:", error);
        if (error instanceof Error) {
            throw new Error(`DynamoDB Query Error: ${error.message}`);
        } else {
            throw new Error("An unknown error occurred during DynamoDB query.");
        }
    }
}

修正业务代码的语法错误 #

if (items.length > 0) {
    const item = items[0];
    console.log("Received item:", item);

    if (item.ignoreNoTraffic !== undefined) {
        return item.ignoreNoTraffic || false;  
    } else {
        return false;
    }
}

方案2：手动处理数据格式（不推荐） #

若坚持使用低阶DynamoDB客户端，需手动处理参数格式和数据转换：

修改查询参数的格式 #

const params = {
    TableName: Tables.ALLOW_LISTED_ITEMS,
    IndexName: "name-index",
    KeyConditionExpression: "#nameAttr = :nameValue",
    ExpressionAttributeNames: {
        "#nameAttr": "name" 
    },
    ExpressionAttributeValues: {
        ":nameValue": { S: this.name }, // 字符串类型需用S标识
    },
};

工具函数中添加数据转换 #

import { unmarshall } from "@aws-sdk/util-dynamodb";

// ...其他代码
if (data.Items.length > 0) {
    return data.Items.map(item => unmarshall(item)); // 转换为普通JSON对象
} else {
    return [];
}

同样修正业务代码的空格问题 #

和方案1中的修正一致，确保访问正确的字段名。

额外检查 #

• 确认name-index的投影属性包含ignoreNoTraffic，可在AWS控制台DynamoDB表的GSI设置中查看修改。
• 验证DynamoDB客户端已正确初始化，且Lambda角色或执行账号具有访问该表和GSI的权限。

内容的提问来源于stack exchange，提问作者AnOldSoul