i18n via t.bind fails to clear translated string when key becomes undefined

[peitschie]

I'm submitting a bug report

• Library Version:
  aurelia-i18n 3.0.0-beta.7

• Webpack AND Version
  webpack 4.27.0
  webpack-cli 3.3.5

• Browser:
  all

• Language:
  TypeScript 3.1.2

Current behavior:
When using the t.bind syntax, translations will not be correctly cleared when bound value becomes undefined. Reproduction at: https://github.com/peitschie/bug-repro-aurelia-i18n-bind.

On initial load, model A is populated, which contains a valid i18n key for both line 1 and 2:

Clicking the Load model B button then causes the bound values to be replaced with a new model that only has the line 1 property defined:

Note that when using the t.bind syntax, the Model A line 2 translation cell is left bound.

This behaviour differs when the key is fed via the t value converter (see the last column in the table), which does correctly clear the translation of line 2 when the second model is loaded.

Expected/desired behavior:
I am expecting the behaviour of t.bind to match the behaviour seen for ${ key & t}. It seems logical to me that if the bound value is set to undefined or cleared, the translation should also be cleared to reflect the new model.

[zewa666]

The reason why it happens is simple, the problem is I can't recall why that was added ;) I'll need to dig up a bit

[zewa666]

PR is the works lets see this shouldn't hopefully take long to fix @peitschie. Love your nickname btw ;)