Stuck on an issue?

Lightrun Answers was designed to reduce the constant googling that comes with debugging 3rd party libraries. It collects links to all the places you might be looking at while hunting down a tough bug.

And, if you’re still stuck at the end, we’re happy to hop on a call to see how we can help out.

TypeError: elements.forEach is not a function

See original GitHub issue

Upon creating a basic form:

<td-dynamic-forms [elements]="myElements" #myForm></td-dynamic-forms>

myElements: ITdDynamicElementConfig[] = [{
   name: "field",
   type: TdDynamicElement.Input,
   label: "Field",
   default: "Some Field",
   required: true
},{...},{...}]

@ViewChild('myForm')
_myForm: TdDynamicFormsComponent;

I get the error

FiltersComponent.html:27 ERROR TypeError: elements.forEach is not a function
    at TdDynamicFormsComponent.set [as elements] (dynamic-forms.component.js:38)
    at updateProp (core.es5.js:11102)
    at checkAndUpdateDirectiveInline (core.es5.js:10794)
    at checkAndUpdateNodeInline (core.es5.js:12332)
    at checkAndUpdateNode (core.es5.js:12271)
    at debugCheckAndUpdateNode (core.es5.js:13132)
    at debugCheckDirectivesFn (core.es5.js:13073)
    at Object.eval [as updateDirectives] (FiltersComponent.html:33)
    at Object.debugUpdateDirectives [as updateDirectives] (core.es5.js:13058)
    at checkAndUpdateView (core.es5.js:12238)

The line it’s identifying is the above html.

What’s especially odd is that this issue came up spontaneously. Everything was working fine, I rebuilt, and this happened.

In the debugger, elements starts as an array containing all of my form elements. Looks totally normal. Later, elements becomes a TdDynamicFormsComponent object:

TdDynamicFormsComponent {_formBuilder: FormBuilder, _dynamicFormsService: TdDynamicFormsService, _changeDetectorRef: ViewRef_, dynamicForm: FormGroup}
controls
:
(...)
dynamicForm
:
FormGroup {validator: null, asyncValidator: null, _pristine: true, _touched: false, _onCollectionChange: ƒ, …}
elements
:
(...)
errors
:
(...)
form
:
(...)
valid
:
(...)
value
:
(...)
_changeDetectorRef
:
ViewRef_ {_view: {…}, _viewContainerRef: null, _appRef: null}
_dynamicFormsService
:
TdDynamicFormsService {}
_formBuilder
:
FormBuilder {}
__proto__
:
Object

And this is where it fails. Elements should always be of type ITdDynamicElementConfig[] in my Typescript, but somehow it gets changed.