async pipe works different with .? operator after upgrade to RC.5

I’m submitting a … (check one with “x”)

[x ] bug report
[ ] feature request
[ ] support request => Please do not submit support request here, instead see https://github.com/angular/angular/blob/master/CONTRIBUTING.md#question

In templates where value is Observable

{{(value|async)?.number}}

Current behavior Cannot read property ‘number’ of null

But when I wrote Pipe with simple value && value.number and changed template

{{value|async|customPipe}}

All works as expected. Sad but I can’t reproduce it in generic project

Expected/desired behavior No error, but when data come then value updated

Please tell us about your environment:

• Angular version: 2.0.0-rc.5
• Browser: Chrome 53
• Language: TypeScript 2.0

[smyth64]

@ericcarraway oh yeah I see… Thanks so much!

[chuckjaz]

The issue is the assumption that generating an expression twice will generate the same expression producing the same value. The generated code looks like:

var currVal_0 = jit_interpolate7(1,'Async value: ',
  ((valUnwrapper.unwrap(self._pipe_async_0.transform(self.context.observable)) == null)? 
    null: 
    valUnwrapper.unwrap(self._pipe_async_1.transform(self.context.observable)).value),'')

This observes two values coming from the pipe instead of just the first one. It checks the first for null then assumes the second will be non-null. The solution is to introduce a temporary storing the result of the first invocation. The would result in code like,

var tmp_0;
var currVal_0 = jit_interpolate7(1,'Async value: ',
    ((tmp_0 = valUnwrapper.unwrap(self._pipe_async_0.transform(self.context.observable)) == null)?
      null: 
      tmp_0.value),'')

I will work on introducing the temporary variable.