How to push object in empty array

Question

My code looks like this :

  router.put('/stories/:story', function(req,res,next){
  Story.findById(req.story._id, function(err, story) {
        if (err) {
            res.send(err);
        }

        story.scenarios.push(req.body); 
        story.save(function(err,story) {
            if (err) {
                res.send(err);
            }
            res.json(story);
        })

    });
});

The req.body contains an object with an image and an audio. I want to be able to update this array with new objects. How do I push new objects to story.scenario (who is null in the beginning).

Now I get an error : 'cannot read property push of null'

Somebody who knows the solution?

Just initialize story.scenarios to an empty array before calling the push() method on it. — IAmDranged
– IAmDranged, Commented Dec 16, 2016 at 2:19

Ping.Goblue · Accepted Answer · 2016-12-16 02:53:33Z

4

The story.scenarios is null at the very beginning so you need to initialize it as [] but you don't want to do it all the time since story.scenarios may already has data.

story.scenarios = story.scenarios || [];
story.scenarios.push(req.body);

answered Dec 16, 2016 at 2:53

Ping.Goblue

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Comments

Meliodas · Accepted Answer · 2016-12-16 04:24:41Z

2

i am assuming story in the parameter is an object and it has _id present it. But still there lies a problem in your code.

You cant just use req.story to access ths passed object. All such objects are accessed using req.params.

Change your code to this, and it should work.

Story.findById(req.params.story._id, function(err, story) {
...
});

Also, i am assuming, in your Story Schema you have declared scenarios as an array, and req.body matches the type you defined in the schema.

answered Dec 16, 2016 at 4:24

Meliodas

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Comments

Sathyanarayanan · Accepted Answer · 2016-12-16 04:51:16Z

2

Just initialize story.scenarios to be an empty array. Then it calling the push() funciton.

ex

story.scenarios = []; story.scanarios.push(someData);

answered Dec 16, 2016 at 4:51

Sathyanarayanan

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