I'm using mongoose schemas for node.js along with express-validator (which has node-validator santiziations and validators).
What's a good way to store price for an item?
I currently have
var ItemSchema = new Schema({
name : { type: String, required: true, trim: true }
, price : Number
});
Price is optional, so I have:
if ( req.body.price ) {
req.sanitize('price').toFloat();
req.assert('price', 'Enter a price (number only)').isFloat();
}
express-validator gives me isNumeric (allows 0 padding), isDecimal, and isInt...I'd rather just convert to decimal and strip all characters, so I'm always inserting 42.00 into db.
I want to allow them to enter $42.00, $42, 42, 42.00 and just store 42.00. How can I accomplish this? and still validate that I'm seeing something resembling a number, for example if they enter 'abc' I want to throw an error back to the form using req.assert.
Also, I suppose currency will eventually become an issue...
Update, I found this post which says to store price as integer in cents, so 4200 http://dba.stackexchange.com/questions/15729/storing-prices-in-sqlite-what-data-type-to-use
I just need a way to convert 4200 to $42.00 when I call item.price and also sanitize and convert the input into 4200.
This is what I ended up doing...
I stored price as cents in database, so it is 4999 for 49.99 as described here: http://dba.stackexchange.com/questions/15729/storing-prices-in-sqlite-what-data-type-to-use
the getPrice will convert it back to readable format, so I can use item.price in my views w/o modifying it.
the setPrice converts it to cents.
model:
var ItemSchema = new Schema({
name : { type: String, required: true, trim: true }
, price : {type: Number, get: getPrice, set: setPrice }
});
function getPrice(num){
return (num/100).toFixed(2);
}
function setPrice(num){
return num*100;
}
I opted to only allow digits and decimal in price field, without $. So they can enter 49, 49.99, 49.00, but not 49.0 or $49
validation using regex:
if ( req.body.price ) {
req.assert('price', 'Enter a price (numbers only)').regex(/^\d+(\.\d{2})?$/);
}
I wish there was a way to allow the $ because I think its a usability issue, just let the user enter it, but strip it off. I'm not sure how to do that and still validate that we have a price and not a bunch of letters for example.
I've been researching for a while on this topic, because I want to store not only price, but version, which both may have trailing 0s that get chopped off when stored as a number. As far as I know, Mongoose/MongoDB can't save a number with trailing zeroes.
Unless you save the number as a string.
Aside from storing numbers in tens or thousands and dividing or parsing, you can also store it as a string. This means, you can always just print it out when you need to show "1.0" or "1.00" by just using the variable without any conversion. Due to JavaScript being untyped, you can still compare it to numbers (make sure it's on the left hand side). Var < 10, for example, will return the right evaluation, even when var is a string. If you're comparing two variables, you'd need to make sure that they're both numbers, though. When you need a number, you can multiply the string by one (var * 1 < var2 * 1), which will ensure that JavaScript treats the var as a number, although it will lose the trailing zeros.
On the one hand, storing it as a string means you need to do a conversion every time you want to use the variable as a number. On the other hand, you would presumably be doing a numeric conversion anyway (var / 100) every time you want to use a cents number as a dollar amount. This option would depend on how frequently you need to your value as a number. Also it may cause bigger bugs if you forget that your variable is a string than if you forget that your variable is in cents.
(However, it's a great fit for version numbers that would only ever be used for display and comparison.)
The numeral module will accomplish that: http://numeraljs.com/ https://www.npmjs.com/package/numeral