LocaleStructure not compatibility single brackets for namespace

[vechnii2007]

Describe the bug

I faced localeStructure and interpolation problem
my json is for variables with single brackets.
like this
"test": "Why {appName}?",
and i used in code
{t("test", { appName: process.env.NEXT_PUBLIC_APP_NAME })}

in the config it was stated that

localeStructure: "{lng} / {ns}",
    interpolation: {
        prefix: "{",
        suffix: "}",
    },

now such an entry does not work, I looked in the code and found that in
node_modules/next-i18next/dist/commonjs/config/createConfig.js
you are doing a replacement
var defaultLocaleStructure = localeStructure.replace ('{{lng}}', lng) .replace ('{{ns}}', defaultNS);
If you change it to single brackets or add an entry, then everything will work.

Occurs in next-i18next version

8.1.2

Steps to reproduce

like this. Use single brackets in common.json
"test": "Why {appName}?",
and i used in code
{t("test", { appName: process.env.NEXT_PUBLIC_APP_NAME })}

Expected behaviour

Expected result, that i can use single or more brackets for localeStructure and interpolation

OS (please complete the following information)

MacOS
Chrome 89.0.4389.90

[isaachinman]

@vechnii2007 The localeStructure config option is completely separate to what character i18next uses for interpolation.

[zachguo]

I ran into the exact same issue.

A simple config like this would turn t(...) off across the site without warning or error.

module.exports = {
  i18n: {
    locales: ['en'],
    defaultLocale: 'en'
  },
  interpolation: {
    prefix: "{",
    suffix: "}",
  }
}

To make custom prefix and suffix work, I had to change localeStructure to match the new prefix and suffix pattern like the suggestion here #620
However, this broke next-i18next and I had to change the hardcoded replace as @vechnii2007 said. Then everything started to work properly.

[sbekrin]

hey @isaachinman, the underlying issue is that next-i18next validates localeStructure assuming it uses double brackets syntax, however it depends on interpolation config on i18next side. It results in defaultNSExists check to always fail in dev mode with non-standard interpolation.[prefix|suffix].

The only workaround for it at the moment is to create an empty file based on custom [prefix|suffix] options e.g. ./public/locales/%{lng}/%{ns}.json (yes, with literlly that being the filesystem path) to trick it into passing the check.

[isaachinman]

@sbekrin @vechnii2007 Yep, that's correct – I misspoke when first commenting on this issue. The interpolation option for the i18next config is not consumed in localeStructure, but it probably makes sense to do so. A PR would be welcome!

[ahakem]

@sbekrin your workaround worked with me, thank you.

[ahakem]

@zachguo this worked with me as well as you tried, but @sbekrin workaround is nice for now, till we made a PR.