AWS node.js lambda request dynamodb but no response (no err, no return data)

Question

I am playing the aws mobilehub with react-native and I was hoping that it can speed up the backend hosting for me.

However, I cannot get its backend API working. After a long run with their docs, I pin down the problem between its lambda function and dynamodb service.

Any thoughts are greatly appreciated!

Problem#1

As the titled says: my aws lambda functions can request its dynamodb but has no response. What went wrong here? Or how can I get debug info from AWS dynamodb? (I gg and enabled Cloudtrial but it doesn't seem to have operation logs of the dynamodb too.)

Lambda side

Here I have the simplest node.js 6.10 codes:

const AWS = require('aws-sdk');
AWS.config.update({region: 'us-east-2'});
const dynamodb = new AWS.DynamoDB.DocumentClient();

exports.handler = function(event, context, callback) {
    var responseCode = 200;
    var requestBody, httpMethod, res;
    console.log("request: " + JSON.stringify(event));

    // Request Body
    requestBody = event.body;

    /*testing dynamodb with put*/

    console.log("PUT begins");
    let putItemParams2 = {
        TableName: "xxxx-mobilehub-xxxx-Test",//tableName
        Item: {businessId:'putItemParams2r3',test:'yooo', hmm:'hhhh'}
    };
    console.log("putItemParams2: ",putItemParams2);
    dynamodb.put(putItemParams2, (err, data) => {
        console.log("putItemParams2");
        if (err) console.log("dynamodb err: ",err, err.stack); // an error occurred
        else     console.log("dynamodb data: ",data);           // successful response
    });
    console.log("PUT end");

    var response = {
        statusCode: responseCode
        //....
    };

    ...
    //comment out context.succeed here to avoid program termination before intended. 
    //console.log("response: " + JSON.stringify(response))
    //context.succeed(response);
};

Logs

When the previouse codes are triggered, from AWS CloudWatch I can see logs:

START RequestId: 3d7c5f7f-1b98-11e8-ad00-93a6d10c8f4e Version: $LATEST
[timestamp] PUT begins
[timestamp] putItemParams2: { TableName: 'xxx-mobilehub-xxxx-Test',
Item: { businessId: 'putItemParams2r3', test: 'yooo', hmm: 'hhhh'}}
[timestamp] put end
END RequestId: 3d7c5f7f-1b98-11e8-ad00-93a6d10c8f4e

So no err, no data, no response. I checked my dynamodb and there is nothing insert.

Extra info

condition#1: this dynamodb table has public access since I want to rule out the auth problem.

condition#2: I ensure that my lambda function has access to these tables. e.g. arn:aws:dynamodb::xxxx:table/xxxx-mobilehub-xxxx- allow everything

condition#3: I build myself a simple node.js to execute the (aws-sdk)and this server works perfectly fine with the same code.. I am able to "get" &"put" items int & out from my dynamodb table.

Problem#2

my react-native code use 'aws-amplify-react-native'. Which the API.put is fine and the lambda function is at least receiving the api call (from problem#1).

However, API.get returns me 403 error, and the lambda function doesn't even has log for this operation..

async function getBusiness(){
    const path = "/Test";
    const api = "TestCRUD";
    let queryGetBusiness = {body: {userId: "hmmm"}};

    try {
        let apiResponse = await API.get(api, path, queryGetBusiness)//.then((data)=>{console.log(data)});
        let apiResponseJson = await JSON.stringify(apiResponse);
        console.log("response from saving Business: " + apiResponseJson);
    }
    catch (e) {console.log(e);}
} 

P.S.(AWS could do much better with this mobilehub.. their documentation is lacking details and awsmobile cloud-api invoke has some problems I guess.)

Bilbao

Answer 1

const AWS = require('aws-sdk');
AWS.config.update({ region: 'us-east-2' });
const dynamodb = new AWS.DynamoDB.DocumentClient();

exports.handler = function (event, context, callback) {
    var responseCode = 200;
    var requestBody, httpMethod, res;
    console.log("request: " + JSON.stringify(event));

    // Request Body
    requestBody = event.body;

    /*testing dynamodb with put*/
    console.log("PUT begins");
    let putItemParams2 = {
        TableName: "xxxx-mobilehub-xxxx-Test",//tableName
        Item: { businessId: 'putItemParams2r3', test: 'yooo', hmm: 'hhhh' }
    };
    console.log("putItemParams2: ", putItemParams2);
    dynamodb.put(putItemParams2, (err, data) => {
        console.log("putItemParams2");
        if (err) console.log("dynamodb err: ", err, err.stack); // an error occurred
        else {
            console.log("dynamodb data: ", data);
            context.succeed(response);
        }
        // Call these here
        console.log("PUT end");
    });

    //console.log("response: " + JSON.stringify(response))
};

Make sure you call context.succeed inside the callback function. Like above.

You can also just use the third argument to handler function - callback instead of context.succeed like callback(null, response);

Jahncke

Thx for the reply! I tried your suggestion by adding context.succeed(data); inside the dynamodb.put() 's callback function, but problem remains. Maybe I'm missing something.. Why would you think this should help though? – Bilbao

403 would mean Forbidden. So, something must be off with your credentials. Are you sure the read and write are public? – Jahncke

yeah, that’s what I thought at first.. I ensured the lambda function has access to use get&query&put& of the table. And I changed the table to public through mobilehub too.. And it show 403 to API.get() but not API.put(), so weird.. – Bilbao