query multiple entities in Google Datastore with a clean syntax - google-app-engine

Question

I'm using node.js with Google App Engine for a class project. My code works fine so I'm not asking how to solve this, but this is ugly beyond reason and I'm assuming there has to be a better way for making this look clean. That isn't part of my grade, just want to know the better way. Also less round trips is always desired so
I have built a basic forum backend but part of creating a forum thread is I need to check that the thread has a unique name and that the user exists. Plan on adding authentication later, but for now just querying the name.
Is there a way to use a single query to get 2 entities by key if they are of different 'kinds'? Nesting queries like this seems bad all around. Not finding a lot of documentation on this subject, or my google-fu is a bit weak. Do something like this in a couple places so would really like to improve on this in particular.
Basic code
router.post('/', function (req, res) {
if (req.body["Name"] == null || typeof req.body["Name"] !== "string")
{
res.json({ success: false, data: "Name was not a valid string." });
return;
}
if (req.body["Creator"] == null || typeof req.body["Creator"] !== "string")
{
res.json({ success: false, data: "Invalid creator submitted for thread creation." });
return;
}
//See if thread is unique
var query = datastore.createQuery('Thread')
.filter('__key__', '=', datastore.key(['Thread', req.body["Name"]]));
datastore.runQuery(query, function (err, entities, nextQuery) {
//
if (err == null && entities.length == 0) {
var query2 = datastore.createQuery('User')
.filter('__key__', '=', datastore.key(['User', req.body["Creator"]]));
datastore.runQuery(query2, function (err2, entities2, nextQuery) {
if (err2 == null && entities2.length >= 1)
{
var threadKey =
{
name: req.body["Name"],
kind: "Thread",
path: ["Thread", req.body["Name"]]
}
var threadData =
{
Creator: req.body["Creator"],
DateCreated: new Date(),
LastUpdated: new Date()
}
datastore.upsert({
key: threadKey,
data: threadData
}, function (err) {
if (err) {
res.json({ success: false, data: "Was unable to add value to datastore for unknown reason." });
return;
}
else {
res.json({ success: true, data: "Was able to add thread to datastore." });
return;
}
});
}
else
{
res.json({ success: false, data: "Cannot create thread because a valid user was not submitted." });
return;
}
});
}
else {
res.json({ success: false, data: "Cannot create thread because a matching name already exists." });
return;
}
});
});

Answer 1

Since queries are on a Kind, you cannot run a single query across Kinds. However, if one Kind is an ancestor of the other, then a single query can get both. For example, if creator were a property of Thread, as the User who created it, then a query on the thread can also contain properties of the creator.
More at: https://cloud.google.com/datastore/docs/concepts/entities#ancestor_paths