Unable to pass default value using $t()

Reporting a bug?

There’s a very high probability of me simply misunderstanding how it’s supposed to work but after some debugging I was not able to find a way to do that.

Based on the documentation we should be able to call:

$t("translation.key", "default value")

However the “default value” is always interpreted as a locale key. Next I tried:

$t("translation.key", null, {default: "default value")})

But options object is never taken into consideration.

After some debugging I was able to find what (I believe) is the culprit: in t(...args) {:

                else if (isPlainObject(arg2)) {
                    named = arg2;
                }
                if (isArray(arg3)) {
                    list = arg3;
                }
                else if (isPlainObject(arg3)) {
                    named = arg3;
                }

Shouldn’t it be:

                else if (isPlainObject(arg3)) {
                    assign(options, arg3);
                }

Since named interpolation object is expected as arg2?

This is sort of further confirmed by looking at $rt which passes options object as the third argument further down and after calling $rt with the options object as the third argument i can confirm that options are passed down the line.

Expected behavior

I expect to be able to pass options object or default value when using $t function

Reproduction

To reproduce try passing default value to the $t function

System Info

Using vue-i18n v9.1.6 with vue 3 in the browser context

Screenshot

No response

Additional context

No response

Validations

• Read the Contributing Guidelines
• Read the Documentation
• Check that there isn’t already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion

[kkyryl]

@kazupon thank you so much for clarifying. I do hope you can update the documentation because this was not an easy discovery 😃

[kazupon]

Unfortunately, $t default value passing doesn’t support in Legacy API (legacy: true). for this reason, it’s kept compatible for vue-i18n@v8.x API.

I think I understand it better now, looks like it’s legacy: true by default and $t is only available in legacy mode ($t is undefined if I set legacy: false).

In Composition API (legacy: false), You can use $t. so you need to set up globalInjection: true in creaetI18n. https://vue-i18n.intlify.dev/guide/advanced/composition.html#implicit-with-injected-properties-and-functions