Safe navigation operator with bracket property accesor

问题

I've run into a case where I can't use the dot notation to access a property, because the property's name contains a dot.

I have an object called translations whose properties contain string translations, for example the Tooltip.O2 property contains the translation for the tooltip of an image:

<img [matTooltip]="translations?.Tooltip.O2" [src]="bed.additionalO2 ? medO2 : noO2">

When I do this, it thinks I'm trying to access a Tooltip object inside translations with an O2 property. I'm aware that I can use the bracket notation to access it:

[matTooltip]="translations['Tooltip.O2']"

However, it does not seem like the safe navigation operator ? can be used with the bracket notation. I've tried to write translations?['Tooltip.O2'], but it caused errors.

I would like to know if there is there a way to access the property using the dot notation, or if there is a way to use the safe navigtaion operator with the bracket notation?

回答1:

Can you initialize the translations obj? It would avoid any error.

translations = {}

回答2:

What I did was the following:

[matTooltip]="translations ? translations['Tooltip.O2'] : null"

回答3:

You can use conditional operator for null check

[matTooltip]="translations ? translations['Tooltip.O2'] : null"

来源：https://stackoverflow.com/questions/48350245/safe-navigation-operator-with-bracket-property-accesor