prevent MongoDB aggregate with $match from returning an empty Array

Question

I have an aggregate function like this

 app.get('/feed', (req, res) => {
 TFBlog.aggregate([  
   { $sample: {size: 5} },
   { $match:  {"published": true} },
  
   ]).then((docs)=>{
   res.render('explore',{docs:docs});
 });
});

Now if aggregate finds a document that doesn't satisfy {published: true} it simply returns an empty array

So in many Use cases, I get 4 or 3 documents in return array instead of 5

I want this function to always return 5 random documents with $match criteria no matter what!!

How can I achieve this please explain?

In your case match condition should pass. it simply returns an empty array is wrong. Can you show us the sample documents with necessary fields and expected output — varman
– varman, Commented Aug 24, 2021 at 8:45

YuTing · Accepted Answer · 2021-08-24 09:21:54Z

1

Move $match condition to the top ?

db.collection.aggregate([  
   { $match:  {"published": true} },
   { $sample: {size: 5} }
])

answered Aug 24, 2021 at 9:21

YuTing

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1 Comment

Tejas Shirnalkar Over a year ago

good God it worked!! thanks man I ignored the staging order !!

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