[RFC] egg-validate support i18n and auto load rule file

[atian25]

Background

Currently, egg-validate don't support i18n:

• 框架本身以及官方插件国际化问题 #589
• 如何修改validate插件错误提示为中文？ #1064
• feat: support i18n and rules config egg-validate#7

Proposal

i18n

• egg-validate will use egg-i18n as optionalDependencies
• change Parameter's translate to ctx.gettext which provide by egg-i8n

rule file

• auto load app/validate/**/*.js, and register to app.validator.addRule(type, fn)

[atian25]

Parameter.addRule(type, check) don't support check to be arrow-function is you want to use this.t(), so maybe it's better to pass translate to rule, that is:

addRule('json', (rule, value, obj) => {
  return rule.__('error message');
});

[atian25]

thinking about drop Parameter dependency, copy it's logic inside

[runfan]

推荐一下 property-validator
https://github.com/nettofarah/property-validator

[atian25]

https://github.com/ianstormtaylor/superstruct

[atian25]

Parameter seems hard to pass a context-level translate fn

@dead-horse any suggest ?

[Ailein]

这个好了？急需多语言支持

[monkeym4ster]

In enterprise-level development, data validation is very necessary and we hope to do so as soon as possible.

[atian25]

@monkeym4ster new version of egg-validate now support custom paramter constructor

https://github.com/eggjs/egg-validate/blob/master/app.js#L27

[JoaoCnh]

@atian25 So how can I translate error messages using gettext or __ method?

// in config.[env].js

exports.validate = {
  translate: error => {
    // something here but I cannot use ctx.__
  }
};

Or do I need to configure a brand new app.validator on my app.js file?

[atian25]

@JoaoCnh you could config it by https://github.com/eggjs/egg-validate#configurations

cc @dead-horse

[JoaoCnh]

@atian25 I realised that and I know that Parameter as a translate method.

My problem is actually the translation. We should translate according to the locale from the request and in said method we have no access to context. So we can't even use gettext.

EDIT:
It's hard to grasp because the messages already come translated from english to the translate method. So a functional translating method is not as straight forward as it should be.

I know yup as very good schema validating lib and it even lets you define labels for each property.

See [here] an example of yup for egg (https://github.com/seekcx/egg-yup)