error ReferenceError: ObjectID is not defined

Not directly a solution but a small typo wasted 10 minutes of my time:

var ObjectId = require('mongodb').ObjectID;

I declared a variable ObjectId with small d but when using the variable, I tried ObjectID with capital D.

node.js angularjs mongodb

ObjectID is not a global variable, it is defined by mongoose (see the documentation):

var fileId = mongoose.Types.ObjectId();

node.js angularjs mongodb

Try This. It'll work in your code properly.

var ObjectId = require('mongodb').ObjectID;

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