[jira] [Commented] (TINKERPOP-2167) Gremlin Javascript Traversal as async iterable

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TINKERPOP-2167?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16776139#comment-16776139 ] 

ASF GitHub Bot commented on TINKERPOP-2167:
-------------------------------------------

joestrouth1 commented on pull request #1071: TINKERPOP-2167 Traversals as async iterables in gremlin-javascript
URL: https://github.com/apache/tinkerpop/pull/1071
 
 
   https://issues.apache.org/jira/browse/TINKERPOP-2167
   
   Summary of changes:
   - Added `[Symbol.asyncIterator]` member to the Traversal class to support `for await ... of` loops (async iterables)
   
   Change was tested by modifying the latest published version of `gremlin` on npm. Reviewed current tests for `gremlin-javascript` and saw none that might conflict.
 
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> Gremlin Javascript Traversal as async iterable
> ----------------------------------------------
>
>                 Key: TINKERPOP-2167
>                 URL: https://issues.apache.org/jira/browse/TINKERPOP-2167
>             Project: TinkerPop
>          Issue Type: Improvement
>          Components: javascript
>    Affects Versions: 3.4.0
>         Environment: Node v10.15.0
>            Reporter: Joe Strouth
>            Priority: Minor
>   Original Estimate: 24h
>  Remaining Estimate: 24h
>
> Traversals in Gremlin javascript are async iterators, as they implement a {{next()}} method that returns a Promise, which resolves to an object with {{value}} and {{done}} properties. It would be helpful if they were also async iterables - traversable via {{for await ... of}} loops.
> {code:javascript}
> (async function() {
>   for await (const continent of g.V().hasLabel('continent').values('desc')) {
>     console.log(continent)
>   }
> })()
> {code}
> Expected output:
> {noformat}
> > Africa
> Antarctica
> North America
> Asia
> Oceania
> Europe
> South America
> {noformat}
> Current output: (Node v10.15.0)
> {noformat}
> > (node:14698) UnhandledPromiseRejectionWarning: TypeError: g.V(...).hasLabel(...).values(...) is not a function or its return value is not async iterable
>     at repl:1:78
>     at repl:1:122
>     at Script.runInThisContext (vm.js:96:20)
>     at REPLServer.defaultEval (repl.js:332:29)
>     at bound (domain.js:395:14)
>     at REPLServer.runBound [as eval] (domain.js:408:12)
>     at REPLServer.onLine (repl.js:639:10)
>     at REPLServer.emit (events.js:187:15)
>     at REPLServer.EventEmitter.emit (domain.js:441:20)
>     at REPLServer.Interface._onLine (readline.js:290:10)
> (node:14698) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
> (node:14698) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
> {noformat}
> This can be achieved by adding a {{[Symbol.asyncIterator]}} method to the Traversal class.



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