Rails 4 的价格验证 [英] Price Validation for Rails 4

问题描述

我的 rails 应用程序中有一个 pieces 模型，每个部分都有一个名为 :price 的小数.我想验证这个价格是两位小数，大于 0，并且小于一百万美元.我查看了许多关于堆栈溢出的来源，每当我为这些验证输入小数时，例如 4.99 ，价格就会变成 4.990000000000000213162820728030055761.我查过的所有验证都发生了这种情况.这是因为我需要在我的数据库中指定小数的精度吗?我该如何解决这个问题?

I have a pieces model in my rails app, and each piece has a decimal called :price. I want to validate that this price is two decimal places, greater than 0, and is less than a million dollars. I have looked at numerous sources on Stack overflow, and whenever I type a decimal for these validations, for example, 4.99 , the price becomes 4.990000000000000213162820728030055761. This has happened for all the validations I have looked up. Is this because I need to specify my precision for the decimal in my database? How can I fix this?

我目前的验证:

validates :price, :presence => true, :format => { :with => /\A(\$)?(\d+)(\.|,)?\d{0,2}?\z/ }

谢谢各位！

推荐答案

我不知道您使用的是哪个数据库，但您可以像这样在迁移中定义精度，

I dont know which database you are using but you can define precision in your migration like this,

add_column :pieces, :price, :decimal, precision: 8, scale: 2

它会给你总共 8 位数字，小数点后有 2 位.

It will give you a total of 8 digits, with 2 after the decimal point.

关于验证，
如果你希望 :price 应该总是有两位小数(即:4.99)，你可以试试这个，

About the validation,
If you want that the :price should always have two decimal place (i.e: 4.99) you can try this,

 validates :price, presence: true, format: { with: /\A\d+(?:\.\d{2})?\z/ }, numericality: { greater_than: 0, less_than: 1000000 }

如果您希望 :price 最多有两位小数或更少(即:4、4.9、4.99)，您可以试试这个，

If you want that the :price should have at most two decimal or less (i.e: 4, 4.9, 4.99) you can try this,

validates :price, presence: true, format: { with: /\A\d+(?:\.\d{0,2})?\z/ }, numericality: { greater_than: 0, less_than: 1000000 }

或者，如果您不想验证精度而只想在将精度四舍五入到数据库之前，您可以使用 round_with_precision.

Or if you dont want to validate precision and just want to round up the precision before you save it to the database you can use round_with_precision.

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