What's the proper way to check if GetItem didn't found record?

[arvenil]

What's the proper way to check if GetItem found item? Checking for resp.Item length?

    if len(resp.Item) == 0 {
        return nil, fmt.Errorf("Item not found")
    }

Full example

    params := &dynamodb.GetItemInput{
        Key: map[string]*dynamodb.AttributeValue{
            "token": {
                S: aws.String(token),
            },
        },
        ProjectionExpression: aws.String("json"),
        TableName:            aws.String("tokens"),
    }

    resp, err := self.db.GetItem(params)
    if err != nil {
        return nil, err
    }

    if len(resp.Item) == 0 {
        return nil, fmt.Errorf("Item not found")
    }

[jasdel]

Correct, checking the length of resp.Item is the best way to know if a GetItem request returned a result. Are you seeing in issues where an empty map for Item causes conflicts?

[arvenil]

The only issue I had was that I first didn't had the check if len(resp.Item) == 0 and so my code was panicking when I tried to get data with resp.Item["json"].
I think this a bit unusual approach, I would rather expect GetItem() returning a package defined error like ErrNotFound (example from sql world https://golang.org/pkg/database/sql/#pkg-variables). Harder to make mistake and end up with panic.

Thanks for answer!

[jasdel]

Thanks for the feedback @arvenil I'll make sure to forward that along to the DynamoDB team. Glad to help. Let us know if you have any other questions, feedback, or ideas/features to improve the SDK.

[0xdevalias]

Just ran into this.. strangest behaviour, would not have expected it. At the very least some extra documentation somewhere on the function would be useful, it seems ambiguous at best:

If there is no matching item, GetItem does not return any data
// and there will be no Item element in the response.

ErrCodeResourceNotFoundException "ResourceNotFoundException"
The operation tried to access a nonexistent table or index. The resource
might not be specified correctly, or its status might not be ACTIVE.

Thanks for this post existing though.