Comments for Delete a Note

From @jayair on Fri Apr 20 2018 17:30:31 GMT+0000 (UTC)

@alex-romanov A couple of things to check. Check the CORS config we set in this chapter - And make sure the IAM policy in the chapter is set properly - There are also some tips on debugging the IAM policy here -

Added a delete function to aws-libs. It works but how can I get information out of the promise I get from delete a file? I want to know if the delete was succesfull e.g. if the file existed. The docs says: * Promise resolves upon successful removal of the object but I don’t know what that means.

 export async function s3Delete(filename) {
     const promise = await Storage.vault.remove(filename);
     //how do I check if object was successfully removed?
     return true;

I’m not entirely sure for this case but for promises with async/await you want to use the try/catch pattern. So wrap it in a try/catch and it should throw an error if it failed to remove it.

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Hey @namelesswc can you help me? I think Storage.remove() needs the key of the file right? How did you get it? I can only get the URL

EDIT: the request doesn’t throw an error, I tried to construct the key myself, it worked, but S3 responds with a 204 and doesn’t delete the file!

I think you just need the key of the file. This is the same as the one we used while uploading the file. If you have the URL strip the rest of the URL info to just get the filename.

@jayair Yeah got it just now reading again! Since the key on the AWS console includes stuff like “private/…” I thought we needed that here as well. Thanks

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Love the tutorial so far. Only I can’t get the delete function to work. The function works when i try

serverless invoke local --function delete --path mocks/delete-event.json

But within the react app I get:

Access to XMLHttpRequest at '' 
from origin 'http://localhost:3000' has been blocked by CORS policy: 
Method DELETE is not allowed by Access-Control-Allow-Methods in preflight response.

POST, PUT works fine…

I also tried to update the response-lib.js to:

function buildReponse(statusCode, body) {
    return {
        statusCode: statusCode,
        headers: {
            "Access-Control-Allow-Origin": "*",
            "Access-Control-Allow-Credentials": true,
            "Access-Control-Allow-Methods": "OPTIONS,POST,GET,PUT,DELETE"
        body: JSON.stringify(body)

with no effect

Can you check the CORS flag in your serverless.yml for this function?

    handler: delete.main
      - http:
          path: notes/{id}
          method: delete
          cors: true
          authorizer: aws_iam

Not sure what is happening. When I call delete using the aws-amplifiy API.del() method, I get a response of 200, but the row is not getting deleted in the dynamoDb table. I have already checked the serverless.yml, Cloudwatch doesn’t seem to have anything, the delete.js api is correct, I am really confused on this one. My CORS configuration is fine too I double checked that.

Nevermind, I forgot an await keyword in the delete.js file. Not really sure why this makes the diffference tho, is it because the function is returning before the async call to the database fires off?

I’m having trouble getting the delete note API endpoint to work. Whenever I try to access it, I end up with a “The Provided Key does not match schema error”, and this is because the userid is null, and I believe this is probably because for some reason the request-context is not getting populated. I don’t know why this is the case, as this is only happening with my delete function, and not my other functions, and I haven’t noticed any differences between them.

Was the await keyword on the call to DynamoDB? If so, then that makes sense. You want to make sure that call completes before returning.

One way to work with these issues is to compare your code to the one in the repo. Let me know if that helps.

I figured out the problem. It was in my serverless.yml, I had not properly indent

 - http:
          path: notes/{id}
          method: put
          cors: true
          authorizer: aws_iam

On any on the functions after my get function. I did not notice because all the other functions were still working despite this.