The Decorators must come directly before an exported class for example:

    @Component({
        ...
    })
    export class someComponent{}

this goes the same for `@Pipe` `@Directive` `@Injectable` and `@NgModule`

This error came to me when I used angular routing and defined routes after `@NgModule` decorator. 

We need to define routes or any other decorater before the `@NgModule` decorator.

    const appRoutes: Routes = [    // define this before @NgModule 
     { path: &#39;&#39;,
       redirectTo: &#39;/home&#39;,
       pathMatch: &#39;full&#39;
     },
     { path: &#39;home&#39;, component: HomeComponent },
    ];


    @NgModule({            // This Decorator should be just before an exported class 
    declarations: [
     AppComponent,
     HeaderComponent,
     HomeComponent
    ],
    imports: [
     BrowserModule,
     RouterModule.forRoot(
       appRoutes,
       { enableTracing: true } // &lt;-- debugging purposes only
     )
    ],
    providers: [],
    bootstrap: [AppComponent]
    })
    export class AppModule { }


How do you iterate over a Pandas Series generated from a `.groupby(&#39;...&#39;).size()` command and get both the group name and count.

As an example if I have:

    foo
    -1     7
     0    85
     1    14
     2     5

how can I loop over them so that in each iteration I would have -1 &amp; 7, 0 &amp; 85, 1 &amp; 14 and 2 &amp; 5 in variables?  

I tried the enumerate option but it doesn&#39;t quite work.  Example:

    for i, row in enumerate(df.groupby([&#39;foo&#39;]).size()):
    	print(i, row)

it doesn&#39;t return -1, 0, 1, and 2 for `i` but rather 0, 1, 2, 3.

How to iterate over Pandas Series generated from groupby().size()

Suppose I have the following module:

    var modulesReq = require.context(&#39;.&#39;, false, /\.js$/);
    modulesReq.keys().forEach(function(module) {
      modulesReq(module);
    });

Jest complains because it doesn&#39;t know about `require.context`:

     FAIL  /foo/bar.spec.js (0s)
    ● Runtime Error
      - TypeError: require.context is not a function

How can I mock it? I tried using [`setupTestFrameworkScriptFile`](http://facebook.github.io/jest/docs/api.html#setuptestframeworkscriptfile-string) Jest configuration but the tests can&#39;t see any changes that I&#39;ve made in `require`.

How can I mock Webpack&#39;s require.context in Jest?

I started to program Angular 2 and I stuck with an error: 

&gt; ts1206 decorators are not valid here


    @Component({   //  ts1206 decorators are not valid here
      selector: &#39;my-app&#39;,
      moduleId: module.id,
      templateUrl: &#39;app.component.html&#39;,
      styleUrls: [&#39;app.component.css&#39;]
    })

**Update:**

My tsconfig.json:

     {
      &quot;compilerOptions&quot;: {
        &quot;target&quot;: &quot;es5&quot;,
        &quot;module&quot;: &quot;commonjs&quot;,
        &quot;moduleResolution&quot;: &quot;node&quot;,
        &quot;sourceMap&quot;: true,
        &quot;emitDecoratorMetadata&quot;: true,
        &quot;experimentalDecorators&quot;: true,
        &quot;removeComments&quot;: false,
        &quot;noImplicitAny&quot;: true,
        &quot;suppressImplicitAnyIndexErrors&quot;: true
      }
    }

what can I do with it? 

    


ts1206 decorators are not valid here, Angular 2

I started to program Angular 2 and I stuck with an error:
> ts1206 decorators are not valid here
<pre><code class="hljs language-less">@Component({ // ts1206 decorators are not valid here
 selector: 'my-app',
 moduleId: module.id,
 templateUrl: 'app.component.html',
 styleUrls: ['app.component.css']
})
</code></pre>
Update:
My tsconfig.json:
<pre><code class="hljs language-json"> {
 "compilerOptions": {
 "target": "es5",
 "module": "commonjs",
 "moduleResolution": "node",
 "sourceMap": true,
 "emitDecoratorMetadata": true,
 "experimentalDecorators": true,
 "removeComments": false,
 "noImplicitAny": true,
 "suppressImplicitAnyIndexErrors": true
 }
}
</code></pre>
what can I do with it?

I am just learning angular2. At the time of applying something at input changes, I am getting the error.

app.ts:

    
    export class AppComponent {
        form: ControlGroup;
    
        constructor(fb: FormBuilder) {
            this.form = fb.group({
                search: []
            });
    
            var search = this.form.find(&#39;search&#39;);
            search.valueChanges
                .debounceTime(400)
                .map(str =&gt; (&lt;string&gt;str).replace(&#39; &#39;,&#39;‐&#39;))
                .subscribe(x =&gt; console.log(x));
        };
    
     }

Error:

[![enter image description here][1]][1]

How to solve this? Am I missing something?

&lt;a href=&quot;http://plnkr.co/edit/MQIQvFYAvsPv9Pu8xZap?p=preview&quot;&gt;Plunker Demo&lt;/a&gt;

**N.B.** I cannot produce anything at plunker as I am writing angular2 first time at plunker now. I have written only my app.ts code at plunker. I have showed the screenshot of error from my local pc. I will be grateful too if you tell me the way of running angular2 project at plunker.


  [1]: http://i.stack.imgur.com/N5Enw.jpg

TypeError: search.valueChanges.debounceTime is not a function

I&#39;m creating an Angular 2 simple CRUD application that allows me to CRUD products. I&#39;m trying to implement the post method so I can create a product. My backend is an ASP.NET Web API. I&#39;m having some trouble because when transforming my Product object to JSON it is not doing it correctly. The 
expected JSON should be like this:

    {
      &quot;ID&quot;: 1,
      &quot;Name&quot;: &quot;Laptop&quot;,
      &quot;Price&quot;: 2000
    }

However, the JSON sent from my application is this:

    {  
       &quot;product&quot;:{  
          &quot;Name&quot;:&quot;Laptop&quot;,
          &quot;Price&quot;:2000
       }
    }

Why is it adding a &quot;product&quot; in the beginning of the JSON? What can I do to fix this? My code:

product.ts

    export class Product {
    
        constructor(
            public ID: number,
            public Name: string,
            public Price: number
        ) { }   
    }

product.service.ts

    import {Injectable}   from &#39;@angular/core&#39;;
    import {Http, Response} from &#39;@angular/http&#39;;
    import { Headers, RequestOptions } from &#39;@angular/http&#39;;
    import {Observable} from &#39;rxjs/Observable&#39;;
    
    import {Product} from &#39;./product&#39;;
    
    @Injectable()
    export class ProductService {
    
        private productsUrl = &#39;http://localhost:58875/api/products&#39;;
    
        constructor(private http: Http) { }
    
        getProducts(): Observable&lt;Product[]&gt; {
            return this.http.get(this.productsUrl)
                .map((response: Response) =&gt; &lt;Product[]&gt;response.json())
                .catch(this.handleError);
        }
    
        addProduct(product: Product) {                
            let body = JSON.stringify({ product });            
            let headers = new Headers({ &#39;Content-Type&#39;: &#39;application/json&#39; });
            let options = new RequestOptions({ headers: headers });
    
            return this.http.post(this.productsUrl, body, options)
                .map(this.extractData)
                .catch(this.handleError);
        }
    
        private extractData(res: Response) {
            let body = res.json();
            return body.data || {};
        }
    
        private handleError(error: Response) {
            console.error(error);
            return Observable.throw(error.json().error || &#39;Server Error&#39;);
        }
    }

create-product.component.ts

    import { Component, OnInit }  from &#39;@angular/core&#39;;
    import { ROUTER_DIRECTIVES } from &#39;@angular/router&#39;;
    
    import { Product } from &#39;../product&#39;
    import { ProductService } from &#39;../product.service&#39;
    
    @Component({
        moduleId: module.id,
        selector: &#39;app-create-product&#39;,
        templateUrl: &#39;create-product.html&#39;,
        styleUrls: [&#39;create-product.css&#39;],
    })
    export class CreateProductComponent {
    
        product = new Product(undefined, &#39;&#39;, undefined);
        errorMessage: string;
    
        constructor(private productService: ProductService) { }
    
        addProduct() {            
            if (!this.product) { return; }
            this.productService.addProduct(this.product)
                .subscribe(
                product =&gt; this.product,
                error =&gt; this.errorMessage = &lt;any&gt;error);
        }
    }

create-product.html

    &lt;div class=&quot;container&quot;&gt;
        &lt;h1&gt;Create Product&lt;/h1&gt;
        &lt;form (ngSubmit)=&quot;addProduct()&quot;&gt;
            &lt;div class=&quot;form-group&quot;&gt;
                &lt;label for=&quot;name&quot;&gt;Name&lt;/label&gt;
                &lt;input type=&quot;text&quot; class=&quot;form-control&quot; required [(ngModel)]=&quot;product.Name&quot; name=&quot;Name&quot;  #name=&quot;ngModel&quot;&gt;
            &lt;/div&gt;
            &lt;div class=&quot;form-group&quot;&gt;
                &lt;label for=&quot;Price&quot;&gt;Price&lt;/label&gt;
                &lt;input type=&quot;text&quot; class=&quot;form-control&quot; required [(ngModel)]=&quot;product.Price&quot; name=&quot;Price&quot;&gt;
            &lt;/div&gt;
            &lt;button type=&quot;submit&quot; class=&quot;btn btn-default&quot; (click)=&quot;addProduct&quot;&gt;Add Product&lt;/button&gt;
        &lt;/form&gt;
    &lt;/div&gt;

How to convert an object to JSON correctly in Angular 2 with TypeScript

I am new to Angular 2 and TypeScript and I&#39;m trying to follow best practices.

Instead of using a simple JavaScript model ({ }), I&#39;m attempting to create a TypeScript class.

However, Angular 2 doesn&#39;t seem to like it.

My code is:

    import { Component, Input } from &quot;@angular/core&quot;;
    
    @Component({
    	selector: &quot;testWidget&quot;,
    	template: &quot;&lt;div&gt;This is a test and {{model.param1}} is my param.&lt;/div&gt;&quot;
    })
    
    export class testWidget {
    	constructor(private model: Model) {}
    }
    
    class Model {
    	param1: string;
    }

and I&#39;m using it as:

    import { testWidget} from &quot;lib/testWidget&quot;;
    
    @Component({
    	selector: &quot;myComponent&quot;,
    	template: &quot;&lt;testWidget&gt;&lt;/testWidget&gt;&quot;,
    	directives: [testWidget]
    })

I&#39;m getting an error from Angular:

&gt; EXCEPTION: Can&#39;t resolve all parameters for testWidget: (?).

So I thought, Model isn&#39;t defined yet... I&#39;ll move it to the top!

Except now I get the exception:

&gt; ORIGINAL EXCEPTION: No provider for Model!

How do I accomplish this??

Edit: Thanks to all for the answer.  It led me to the right path.

In order to inject this into the constructor, I need to add it to the providers on the component. 

This appears to work:

    import { Component, Input } from &quot;@angular/core&quot;;

    class Model {
        param1: string;
    }

    @Component({
        selector: &quot;testWidget&quot;,
        template: &quot;&lt;div&gt;This is a test and {{model.param1}} is my param.&lt;/div&gt;&quot;,
        providers: [Model]
    })
    
    export class testWidget {
        constructor(private model: Model) {}
    }
    


How do I declare a model class in my Angular 2 component using TypeScript?

I am trying to use Angular2 router guards to restrict access to some pages in my app.  I am using Firebase Authentication.  In order to check if a user is logged in with Firebase, I have to call `.subscribe()` on the `FirebaseAuth` object with a callback.  This is the code for the guard:

&lt;!-- language: ts --&gt;

    import { CanActivate, Router, ActivatedRouteSnapshot, RouterStateSnapshot } from &#39;@angular/router&#39;;
    import { AngularFireAuth } from &quot;angularfire2/angularfire2&quot;;
    import { Injectable } from &quot;@angular/core&quot;;
    import { Observable } from &quot;rxjs/Rx&quot;;
    
    @Injectable()
    export class AuthGuard implements CanActivate {
    
        constructor(private auth: AngularFireAuth, private router: Router) {}
        
        canActivate(route:ActivatedRouteSnapshot, state:RouterStateSnapshot):Observable&lt;boolean&gt;|boolean {
            this.auth.subscribe((auth) =&gt; {
                if (auth) {
                    console.log(&#39;authenticated&#39;);
                    return true;
                }
                console.log(&#39;not authenticated&#39;);
                this.router.navigateByUrl(&#39;/login&#39;);
                return false;
            });
        }
    }

When a navigate to a page that has the guard on it, either `authenticated`, or `not authenticated` is printed to the console (after some delay waiting for the response from firebase).  However, the navigation is never completed.  Also, if I am not logged in I am redirected to the `/login` route.  So, the issue I am having is `return true` doesn&#39;t display the requested page to the user.  I&#39;m assuming this is because I am using a callback, but I am unable to figure out how to do it otherwise.  Any thoughts?

Angular2 canActivate() calling async function

So far we are used to **tsd** or (The better version of it) **typings**

But now that TypeScript 2 offers the new `@types` feature, how should I convert my current project to work with @types?

I have tsd.json (typings.json is some cases) with all the dependencies, what are the steps to do the move to TypeScript 2?

What are the *new* best practices?
Does @types support specific versions?



How should I use @types with TypeScript 2

I&#39;m using react/es6/webpack. I want to show the date of the build and git hash somewhere in my app. What&#39;s the best approach?

Including git commit hash and date in webpack build

I am new to Angular 2. I have seen in every project there is plugin called `platform-browser`. 

    &quot;@angular/platform-browser&quot;: &quot;2.0.0-rc.4&quot;,
    &quot;@angular/platform-browser-dynamic&quot;: &quot;2.0.0-rc.4&quot;,

I don&#39;t really know what is the usage of it. Someone can please explain me
- What is the usage of `platform-browser`?
- What is the problem if we not use `platform-browser`?

Content Type	Original Author	Original Content on Stackoverflow
Question	Elior Sastiel	View Question on Stackoverflow
Solution 1 - Typescript	Jarod Moser	View Answer on Stackoverflow
Solution 2 - Typescript	Shubham Jain	View Answer on Stackoverflow

ts1206 decorators are not valid here, Angular 2

Typescript Problem Overview

Typescript Solutions

Solution 1 - Typescript

Solution 2 - Typescript

How can I mock Webpack's require.context in Jest?

How to iterate over Pandas Series generated from groupby().size()

Attributions