10.1 Time zones

Finding out the Locale

A locale is a set of descriptors for a particular geographical region, and can include specific language habits, text formatting, cultural idioms and a multitude of other settings. A locale's name is usually composed of three parts. First (and mandatory) is the locale's language abbreviation, such as "en" for English or "zh" for Chinese. The second part is an optional country specifier, and follows the first with an underscore. This specifier allows web applications to distinguish between different countries which speak the same language, such as "en_US" for U.S. English, and "en_UK" for British English. The last part is another optional specifier, and is added to the locale with a period. It specifies which character set to use, for instance "zh_CN.gb2312" specifies the gb2312 character set for Chinese.

Go defaults to the "UTF-8" encoding set, so i18n in Go applications do not need to consider the last parameter. Thus, in our examples, we'll only use the first two parts of locale descriptions as our standard i18n locale names.

On Linux and Solaris systems, you can use the locale -a command to get a list of all supported regional names. You can use this list as examples of some common locales. For BSD and other systems, there is no locale command, but the regional information is stored in /usr/share/locale.

Setting the Locale

Now that we've defined what a locale is, we need to be able to set it according to visiting users' information (either from their personal settings, the visited domain name, etc.). Here are some methods we can use to set the user's locale:

Setting the Locale by domain name

We can set a user's locale via the domain name itself when the application uses different domains for different regions. For example, we can use www.asta.com as our default English website, and the domain name www.asta.cn as its Chinese counterpart. By application of this domain name and set up inside the correspondence between the respective locale, you can set up regions. This treatment has several advantages:

Via a URL can be very distinctive identification
Users can be very intuitive to know the domain name will be visiting the site in that language
Go program is implemented in a very simple and convenient, can be achieved through a map
Conducive to search engine crawlers can improve the site's SEO

We can use the following code to implement a corresponding domain name locale:

if r.Host == "www.asta.com" {
	i18n.SetLocale("en")
} else if r.Host == "www.asta.cn" {
	i18n.SetLocale("zh-CN")
} else if r.Host == "www.asta.tw" {
	i18n.SetLocale("zh-TW")
}

Of course, in addition to the entire domain settings outside the region, we can also be set through the sub-domain areas, such as "en.asta.com" for English sites, "cn.asta.com" indicates Chinese site. Realization of the code is as follows:

prefix:= strings.Split(r.Host,".")

if prefix[0] == "en" {
	i18n.SetLocale("en")
} else if prefix[0] == "cn" {
	i18n.SetLocale("zh-CN")
} else if prefix[0] == "tw" {
	i18n.SetLocale("zh-TW")
}

Locale setting by domain name as shown above advantages, but we generally do not develop Web applications, when used in this way, because first of all domain names cost is relatively high, the development of a Locale need a domain name, and often the name of the domain does not necessarily uniform apply to, and secondly we do not want to go to each site localization of a configuration, but more is to use the url method with parameters, see the following description.

Locale parameter settings from the domain name

The most common way is to set the Locale to bring inside in the URL parameters, such www.asta.com/hello?locale=zh or www.asta.com/zh/hello. So that we can set the region: i18n.SetLocale(params["locale"]).

This setup has almost speaking in front of the domain name Locale setting all the advantages, it uses a RESTful way, so we do not need to add additional methods to deal with. However, this approach requires a link inside each one corresponding increase in the parameter locale, this may be a bit complicated and sometimes quite cumbersome. However, we can write a generic function that url, so that all the link addresses are generated through this function, then this function which increases locale = params [" locale "] parameter to alleviate it.

Maybe we want to look more RESTful URL address that, for example: www.asta.com/en/books (English site) and www.asta.com/zh/books (Chinese site), this approach is more conducive to the URL SEO, but also more friendly for the user, can be accessed through the URL of the site that intuitive. Then such a URL address to get through router locale(reference section which describes the router REST plug-in implementation):

mux.Get("/:locale/books", listbook)

From the client settings area

In some special cases, we need the client's information rather than through the URL to set Locale, such information may come from the client to set the preferred language( the browser settings), the user's IP address, the user at the time of registration fill the location information. This approach is more suitable for Web -based applications.

Accept-Language

When a client requests information in the HTTP header there Accept-Language, clients will generally set this information, the following is the Go language to achieve a simple Accept-Language under implementation sets the region code:

AL := r.Header.Get("Accept-Language")
if AL == "en" {
	i18n.SetLocale("en")
} else if AL == "zh-CN" {
	i18n.SetLocale("zh-CN")
} else if AL == "zh-TW" {
	i18n.SetLocale("zh-TW")
}

Of course, in practical applications, it may require more rigorous judgment to be set area

IP Address

Another set of the client area is the user access IP, we according to the corresponding IP library, corresponding to the IP access to areas of the world that is more commonly used GeoIP Lite Country this library. This setting regional mechanism is very simple, we only need to check the user's IP IP database and then return to the country regions, according to the results returned by setting the corresponding regions.

User profile

Of course, you can also let users provide you with drop-down menus or whatever way set the appropriate locale, then we have the information entered by the user, it is saved to the account associated with the profile, when the user login again, this time to set up replicated to the locale setting, so that you can guarantee that every time the user accesses are based on their previously set locale to get the page.

Summary

Through the above description shows that you can set the Locale There are many ways that we should be selected according to the different needs of different settings Locale way to allow a user to its most familiar way to get the services we provide, improve application user friendliness.

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