Angular2 AoT - Expression form not supported

问题:

I'm trying to use ngc to compile angular 2.4.4:

Error: Error encountered resolving symbol values statically. Expression form not supported (position 52:9 in the original .ts file), resolving symbol DEFAULT_APP_STATE in... 

It looks like it is complaining about how i'm exporting a constant for @ngrx/store.

I tried changing the constant into an exported function... as well as all of the properties.

Previously:

export const DEFAULT_APP_STATE = {         Offline: DEFAULT_APP_OFFLINE_STATE,         Initialized: DEFAULT_APP_INITIALIZED_STATE,         Console: DEFAULT_CONSOLE_DICTIONARY,         Identity: DEFAULT_IDENTITY,         HamburgerState: DEFAULT_HAMBURGER_STATE,         Customers: DEFAULT_CUSTOMER_STATE,         UserMenuVisibility: DEFAULT_USER_MENU_VISIBILITY,         StreamViewMultiple: DEFAULT_STREAM_VIEW_MULTIPLE_STATE,         StreamViewSingle: DEFAULT_STREAM_VIEW_SINGLE_STATE,         Streams: DEFAULT_STREAM_DICTIONARY,         Destinations: DEFAULT_DESTINATION_DICTIONARY,         DestinationList: DEFAULT_DESTINATION_LIST_STATE,         IDestinationTranscodeModal: DEFAULT_DESTINATION_TRANSCODE_MODAL_STATE     } as IAppState; 

Presently:

export function DEFAULT_APP_STATE() {     return {         Offline: DEFAULT_APP_OFFLINE_STATE(),         Initialized: DEFAULT_APP_INITIALIZED_STATE(),         Console: DEFAULT_CONSOLE_DICTIONARY(),         Identity: DEFAULT_IDENTITY(),         HamburgerState: DEFAULT_HAMBURGER_STATE(),         Customers: DEFAULT_CUSTOMER_STATE(),         UserMenuVisibility: DEFAULT_USER_MENU_VISIBILITY(),         StreamViewMultiple: DEFAULT_STREAM_VIEW_MULTIPLE_STATE(),         StreamViewSingle: DEFAULT_STREAM_VIEW_SINGLE_STATE(),         Streams: DEFAULT_STREAM_DICTIONARY(),         Destinations: DEFAULT_DESTINATION_DICTIONARY(),         DestinationList: DEFAULT_DESTINATION_LIST_STATE(),         IDestinationTranscodeModal: DEFAULT_DESTINATION_TRANSCODE_MODAL_STATE()     } as IAppState; };  

I'm using this in my imports[] as such:

... imports: [     ...,     StoreModule.provideStore({                 Offline: APP_OFFLINE_REDUCER,                 Initialized: APP_INITIALIZED_REDUCER,                 Console: CONSOLE_REDUCER,                 Identity: IDENTITY_REDUCER,                 Customers: CUSTOMER_REDUCER,                 Hamburger: HAMBURGER_REDUCER,                 UserMenuVisibility: USER_MENU_VISIBILITY_REDUCER,                 StreamViewSingle: STREAM_VIEW_SINGLE_REDUCER,                 StreamViewMultiple: STREAM_VIEW_MULTIPLE_REDUCER,                 Streams: STREAM_REDUCER,                 Destinations: DESTINATION_REDUCER,                 DestinationList: DESTINATION_LIST_REDUCER,                 DestinationTranscodeModal: DESTINATION_TRANSCODE_MODAL_REDUCER             }, DEFAULT_APP_STATE()),     ... ],... 

Each reducer has already been changed from a constant lambda declaration to an exported function

old

export const reducer = () => { ...}  

new

export function reducer() { ... } 

Can anyone make sense of what the ngc compiler is complaining about?

回答1:

In this specific instance, the ngc compliation stopped complaining once I modified the original constant declaration to not us the "... as IAppState" clause.

Didn't work:

export const DEFAULT_APP_STATE = {         Offline: DEFAULT_APP_OFFLINE_STATE,         Initialized: DEFAULT_APP_INITIALIZED_STATE,         Console: DEFAULT_CONSOLE_DICTIONARY,         Identity: DEFAULT_IDENTITY,         HamburgerState: DEFAULT_HAMBURGER_STATE,         Customers: DEFAULT_CUSTOMER_STATE,         UserMenuVisibility: DEFAULT_USER_MENU_VISIBILITY,         StreamViewMultiple: DEFAULT_STREAM_VIEW_MULTIPLE_STATE,         StreamViewSingle: DEFAULT_STREAM_VIEW_SINGLE_STATE,         Streams: DEFAULT_STREAM_DICTIONARY,         Destinations: DEFAULT_DESTINATION_DICTIONARY,         DestinationList: DEFAULT_DESTINATION_LIST_STATE,         IDestinationTranscodeModal: DEFAULT_DESTINATION_TRANSCODE_MODAL_STATE     } as IAppState; 

Worked:

export const DEFAULT_APP_STATE: IAppState = {         Offline: DEFAULT_APP_OFFLINE_STATE,         Initialized: DEFAULT_APP_INITIALIZED_STATE,         Console: DEFAULT_CONSOLE_DICTIONARY,         Identity: DEFAULT_IDENTITY,         HamburgerState: DEFAULT_HAMBURGER_STATE,         Customers: DEFAULT_CUSTOMER_STATE,         UserMenuVisibility: DEFAULT_USER_MENU_VISIBILITY,         StreamViewMultiple: DEFAULT_STREAM_VIEW_MULTIPLE_STATE,         StreamViewSingle: DEFAULT_STREAM_VIEW_SINGLE_STATE,         Streams: DEFAULT_STREAM_DICTIONARY,         Destinations: DEFAULT_DESTINATION_DICTIONARY,         DestinationList: DEFAULT_DESTINATION_LIST_STATE,         IDestinationTranscodeModal: DEFAULT_DESTINATION_TRANSCODE_MODAL_STATE     }; 

回答2:

AoT needs to evaluate some code statically and it currently can't evaluate function content.

https://github.com/rangle/angular-2-aot-sandbox#current-status

This might work

export const MY_APP_STATE = DEFAULT_APP_STATE(); imports: [     ...,     StoreModule.provideStore({                 Offline: APP_OFFLINE_REDUCER,                 Initialized: APP_INITIALIZED_REDUCER,                 Console: CONSOLE_REDUCER,                 Identity: IDENTITY_REDUCER,                 Customers: CUSTOMER_REDUCER,                 Hamburger: HAMBURGER_REDUCER,                 UserMenuVisibility: USER_MENU_VISIBILITY_REDUCER,                 StreamViewSingle: STREAM_VIEW_SINGLE_REDUCER,                 StreamViewMultiple: STREAM_VIEW_MULTIPLE_REDUCER,                 Streams: STREAM_REDUCER,                 Destinations: DESTINATION_REDUCER,                 DestinationList: DESTINATION_LIST_REDUCER,                 DestinationTranscodeModal: DESTINATION_TRANSCODE_MODAL_REDUCER             }, MY_APP_STATE),     ... ],... 

Just move function calls out and reference a value instead.

文章来源: Angular2 AoT - Expression form not supported