Just a quick troubleshooting gotcha:

AOT, Angular2 compile error:

Error: Error encountered resolving symbol values statically. Expression form not supported (position 28:20 in the original .ts file), resolving symbol ToolsModule in C:/Workspaces/.../app/tools/tools.module.ts

leading comma in array values


declarations: [
   , MainComponent  <<<< Issue.
  , SubComponent
  ]

The equivalent to lambda expressions in Angular TypeScript (Javascript)

For filtering a list in C# we have :

var filteredList = List.Where(l => l.active);]

JS equivalent :

var filteredList = list.filter((l) => { return l.active == true; });

C# - Test for list values

var isListPopulated = List.Any( l => l.amount >= 0);

JS - Test for list values

var isListPopulated = list.filter((l) => { return l.amount >= 0; }).length > 0;

C# - Get first list item

var topItem = List.First( l => l.amount >= 0);

JS - Get first list item

var topItem = list.filter((l) => { return l.amount >= 0; })[0];

NB C# First() throws an exception if there is no match. As does the JS equivalent.

C# - Get first list item or null if none exist

var topItem = List.FirstOrDefault( l => l.amount >= 0);

JS - Get first list item or null if none exist (combo of the Any + First)

var filteredList = list.filter((l) => { return l.amount >= 0; });

var topItem = filteredList.length > 0 ? filteredList[0] : null;

Resolving "Invalid column name" Exception

"System.Data.SqlClient.SqlException: Invalid column name 'Client_ClientId'."

A valid relationship to the Client entity model could not be determined. In our case, there were duplicate virtual references in the Client model (table) to the Document model (table).

The Document model had the following properties:

        public Nullable ClientId { get; set; }
        public virtual Client Client { get; set; }

However, the Client model had the following duplicate properties:

        public virtual ICollection ClientDocuments { get; set; }
        public virtual ICollection Documents { get; set; }

Removal of the duplicate eliminated the exception message.

Angular2 rollup project errors

Receiving the following error message in the Task Runner Explorer window when rolling up an Angular2 app using Gulp (VisualStudio 2015) 

To fix the following error,

Unhandled promise rejection (rejection id: 1): Error: 'ChartsModule' is not exported by node_modules\ng2-charts\ng2-charts.js

Add the following lines: 

var charts_module_2 = require('./components/charts/charts');
exports.ChartsModule = charts_module_2.ChartsModule;

Inside of

\node_modules\ng2-charts\ng2-charts.js



To fix the following error,

Unhandled promise rejection (rejection id: 1): Error: 'MapsAPILoader' is not exported by node_modules\angular2-google-maps\core\index.js

Add the following lines:

var core_module_2 = require('./core.umd');
exports.MapsAPILoader = core_module_2.MapsAPILoader;

Inside of

node_modules/angular2-google-maps/core/index.js

For help fixing this error see https://github.com/rollup/rollup/wiki/Troubleshooting#name-is-not-exported-by-module 



To fix the following error,

Unhandled promise rejection (rejection id: 1): Error: 'FileUploader' is not exported by node_modules\ng2-file-upload\index.js

Add the following lines: 

var file_uploader_module_2 = require('./components/file-upload/file-uploader.class');
exports.FileUploader = file_uploader_module_2.FileUploader;
Inside of

\ node_modules\ng2-file-upload\ng2-file-upload.js (2.2.1)

Angular2 issues with Vaadin Combo box. Using [ngModel] and (selected-item-changed) to set selected id value. not using [(ngModel)] selected-item-changed fires 3 times: 1) with 1st item in list - no matter what selection 2) same value as first 3) null value result: no selection is made. findings: item-value-path has wrong path. selected-item-changed fires 2 times: 1) with correctly selected value 2) null value result: no selection is made. findings: selected-item-changed handler was (re)setting the selected value to an invalid property, resulting in value being null a.selected-item-changed fires 2 times: 1.a) with correctly selected value 2.a) with 1st item in list result: wrong selection is made. b.selected-item-changed fires 2 times: 1.b) with previous selection 2.b) with correct value result: correct selection is made. c.selected-item-changed fires 1 time: 1.c) with correct value findings: item-value-path was using a key that could be null for selected item. selected-item-changed handler was (re)setting the selected value to correct value again, resulting in second change event firing. If key was valid and unique, selection was made correctly.