stack-overflow/53972854

gistfile1.txt

const mongoose = require( "mongoose" );

mongoose.connect( "mongodb://localhost:27017/test", { useNewUrlParser : true } );

const Item = mongoose.model( "Item", {
    inv : {
        type : Object,
        default : {}
    }
} );

const item = new Item( { inv : { foo : "bar" } } );

item.save().then( item => {
    console.log( item );
    delete item.inv.foo;
    item.save().then( item => {
        console.log( item );
    } );
} );