NativeScript/NativeScript

Can not use nested object method in expression for binding

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#6,727 opened on Dec 19, 2018

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 (6 comments) (0 reactions) (0 assignees)TypeScript (1,634 forks)batch import
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Description

Environment

  • CLI: 5.0.1
  • Cross-platform modules: 5.0.5
  • Android Runtime: 5.0.0
  • iOS Runtime: not installed

To Reproduce

class ViewModel extends Observable {
    public obj = {
        fun: function () {
            return "It's fun()"
        }
    }
}

const vm = new ViewModel();

<Label text="{{ obj.fun() }}"/>

Binding: Run-time error occured in file: undefined at line: undefined and column: undefined

Same result if it used, as ListView item bindingContext.

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Contributor guide

Research direction
Trace the binding expression evaluation code to identify why method calls on nested objects fail. Focus on the expression parser and the source where `obj.fun()` is evaluated. Look at the way property access is handled before the method call.
Tech stack
javascripttypescript
Domain
mobile
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
JavaScriptTypeScriptGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65