Inserting subdocuments into an existing Collection

my model schema

    const mongoose = require('mongoose')

    const GeoSchema = mongoose.Schema({
        type: {
            type: String,
            enum: ['Point', 'LineString', 'Polygon'],
            default: "Point"
        },
        coordinates: {
            type: [Number],
            index: "2dsphere"
        }
    })

    const EventSchema = mongoose.Schema({
        eventDate: {
            type: Date
        },
        eventTitle: {
            type: String,
            required: true,
            minlength: 3
        },
        eventDescription: {
            type: String,
            minlength: 3
        },
        eventImageUrl: {
            type: String
        },
        eventLink: {
            type: String
        },
        eventAudio: {
            type: String
        },
        eventLocation: GeoSchema,
    })

    const StorySchema = mongoose.Schema({
        storyTitle: {
            type: String,
            minlength: 5,
            required: true
        },
        storySummary: {
            type: String
        },
        storyImageUrl: {
            type: String,
            required: true
        },
        storyStatus: {
            type: String,
            default: 'public',
            enum: ['public', 'private']
        },
        storyCreator: {
            type: mongoose.Types.ObjectId,
            // required: true,
            ref: 'User'
        },
        storyReferences: [String],
        storyTags: [String],
        storyMapStyle: {
            type: String,
            default: 'mapbox://styles/mapbox/light-v9',
        },
        likes: [{
            type: mongoose.Types.ObjectId,
            ref: 'User'
        }],
        event: [ EventSchema ]
    }, {timestamps: true})

    module.exports = mongoose.model('Story', StorySchema)

routes

router.put('/:story_id/update', (req, res) => {
    const {
        eventDate,
        eventTitle,
        eventDescription,
        eventImageUrl,
        eventLink,
        eventAudio } = req.body

    console.log('eventDate',eventDate)

    Story.findByIdAndUpdate(
        { _id: req.params.story_id},
        {
            $push:
            { event: 
                {
                eventDate,
                eventTitle,
                eventDescription,
                eventImageUrl,
                eventLink,
                eventAudio
            }}
        })
})