I am using mongoose Schemas to create models for my mongodb, and I am wondering wether or not to use default values. I understand that using default values are good for createdAt and similar values, but what about in my case, where I have schemas with a bunch of properties, which potentially could lead to a lot of null pointers in the client. Should I solve this using default values on my mongoose schemas, or should I deal with this issue on the client side, or even nodejs?
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Is it a problem when they are missing/null? If so, why?Thomas Bormans– Thomas Bormans2017-01-25 20:27:25 +00:00Commented Jan 25, 2017 at 20:27
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Well, if it is not dealt with, accessing a property e.g obj['someProperty'] will throw an error.mrlarssen– mrlarssen2017-01-25 21:01:17 +00:00Commented Jan 25, 2017 at 21:01
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Obviously. If it really bothers you writing checks both in the FE & BE, I would use default values...Thomas Bormans– Thomas Bormans2017-01-26 07:08:21 +00:00Commented Jan 26, 2017 at 7:08
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My answer would be simply to avoid using default values if a schema field is unused. In my production Node/Mongo/Mongoose app, there are a number of points that help make this a good strategy:
- Mongoose does not save unused fields i.e. those that don't have a default in the schema and are not set during the create operation. This saves a lot of Mongo disk space since every Mongo document stores the field name and values in a JSON document. I've seen as much as a 60% gain in disk space from using short field names and avoiding un-necessary defaults.
- When you are writing code in NodeJS that deals with the database via Mongoose queries, you get Mongoose-decorated objects that can deal with presence / absence of schema properties, even if not set. Note that this is the default behavior if you do a model.find() operation. As far as the back-end code, you don't need to worry about dealing with Javascript undefined exceptions. Mongoose will help set any properties that are declared in the schema and it will also conversely ignore (and not serialize to the DB) any properties you add that are not declared.
- Note that the above functionality is expensive for queries. Bottom line: if you are writing code in NodeJS to get/set props while performing create or update methods, using the Mongoose-decorated objects will deal with schema defaults etc. If you are just querying to send data back to the front-end (as is), you should use the .lean() method on your Mongoose queries - they are significantly faster.
In the front-end, fields that have no values but need defaults can be dealt with easy enough - attributes that are 1-level deep:
var someField = myMongoDoc.attrWithoutDefault || 'default value';Attributes that are nested (e.g. myMongoDoc.attr1.subAttr1) can be tested using a library like lodash (see https://lodash.com/docs#get)
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mrlarssen
Perfect! Thank you