Angular HTTP GET with TypeScript error http get map is not a function in null

Question

I have a problem with HTTP in Angular    I just want to GET a JSON list and show it in the view    Service class  import  Injectable  from  angular2 core   import  Hall  from    hall   import  Http  from  angular2 http    Injectable   export class HallService       public http Http      public static PATH string    app backend            constructor http Http            this http http             getHalls                return this http get HallService PATH    hall json   map  res Response    gt  res json               And in the HallListComponent I call the getHalls method from the service   export class HallListComponent implements OnInit       public halls Hall        public  selectedId number       constructor private  router Router                  private  routeParams RouteParams                  private  service HallService            this  selectedId     routeParams get  id               ngOnInit             this  service getHalls   subscribe  halls Hall     gt                this halls halls                        However  I got an exception       TypeError  this http get      map is not a function in  null    hall-center component  import  Component  from  angular2 core   import  RouterOutlet  from  angular2 router   import  HallService  from    hall service   import  RouteConfig  from  angular2 router   import  HallListComponent  from    hall-list component   import  HallDetailComponent  from    hall-detail component    Component       template            lt h2 gt my app lt  h2 gt           lt router-outlet gt  lt  router-outlet gt             directives   RouterOutlet       providers   HallService       RouteConfig        path               name   HallCenter   component HallListComponent  useAsDefault true        path    hall-list   name   HallList   component HallListComponent      export class HallCenterComponent     app component  import  Component  from  angular2 core   import  ROUTER DIRECTIVES  from  angular2 router   import  RouteConfig  from  angular2 router   import  HallCenterComponent  from    hall hall-center component    Component       selector   my-app       template             lt h1 gt Examenopdracht Factory lt  h1 gt           lt a  routerLink     HallCenter    gt Hall overview lt  a gt           lt router-outlet gt  lt  router-outlet gt             directives   ROUTER DIRECTIVES       RouteConfig        path    hall-center       name  HallCenter  component HallCenterComponent useAsDefault true     export class AppComponent       tsconfig json       compilerOptions          target    ES5        module    system        moduleResolution    node        sourceMap   true       emitDecoratorMetadata   true       experimentalDecorators   true       removeComments   false       noImplicitAny   false         exclude          node modules

User · Answer

import  rxjs add operator map     will resolve your problem  I tested it in angular 5 2 0 and rxjs 5 5 2

User · Answer

Plus what  mlc-mlapis commented  you re mixing lettable operators and the prototype patching method  Use one or the other   For your case it should be  import   Injectable   from   angular core   import   HttpClient   from   angular common http   import   Observable   from  rxjs   import  rxjs add operator map     Injectable   export class SwPeopleService       people    this http get  https   swapi co api people           map  res any    gt  res results        constructor private http  HttpClient          https   stackblitz com edit angular-http-observables-9nchvz file app 2Fsw-people service ts

User · Answer

With Angular 5 the RxJS import is improved    Instead of  import  rxjs add operator map     We can now  import   map   from  rxjs operators

User · Answer

this is happening because you are using the rxjs and in rxjs function are not static which means you can t call them directly you have to call the methods inside the pipe and import that function from the rxjs library   But if you are using rxjs-compat then you just need to import the rxjs-compat operators

User · Answer

Angular version 6  0 6 8   rxjs version 6   6 0 0   this solution is  for        angular-devkit core    0 6 8      rxjs     6 0 0    as we all know angular is being developed every day so there are lots of changes every day and this solution is for angular 6 and rxjs 6 first to work with http yo should import it from     after all you have to declare the HttpModule in app module ts  import   Http   from   angular http     and you have to add HttpModule to Ngmodule -  imports     imports        HttpModule      BrowserModule      FormsModule      RouterModule forRoot appRoutes         second  to work with map you should first import pipe     import   pipe   from  rxjs     third you need the map function  import from     import   map   from  rxjs operators     you have to use map inside pipe like this exemple      constructor public http Http           getusersGET            return this http get  http   jsonplaceholder typicode com users   pipe           map res   gt  res json                  that works perfectly good luck

User · Answer

Using Observable subscribe directly should work    Injectable   export class HallService       public http Http      public static PATH string    app backend            constructor http Http            this http http             getHalls                        No map            return this http get HallService PATH    hall json              export class HallListComponent implements OnInit       public halls Hall                    ngOnInit             this  service getHalls               subscribe halls   gt  this halls   halls json         lt  lt --

User · Answer

True  RxJs has separated its map operator in a separate module and now you need to explicity import it like any other operator   import rxjs add operator map   and you will be fine

User · Answer

Global import is safe to go with   import  rxjs Rx

User · Answer

For Angular versions 5 and above  the updated importing line looks like    import   map   from  rxjs operators     OR   import   map   from  rxjs operators     Also these versions totally supports Pipable Operators so you can easily use  pipe   and  subscribe     If you are using Angular version 2  then the following line should work absolutely fine    import  rxjs add operator map     OR   import  rxjs add operators map     If you still encounter a problem then you must go with     import  rxjs Rx     I won t prefer you to use it directly bcoz it boosts the Load time  as it has a large number of operators in it  useful and un-useful ones  which is not a good practice according to the industry norms  so make sure you try using the above mentioned importing lines first  and if that not works then you should go for rxjs Rx

User · Answer

I have a solution of this problem    Install this package   npm install rxjs 6 rxjs-compat 6 --save   then import this library    import  rxjs add operator map    finally restart your ionic project then     ionic serve -l

User · Answer

I think that you need to import this   import  rxjs add operator map    Or more generally this if you want to have more methods for observables  WARNING  This will import all 50  operators and add them to your application  thus affecting your bundle size and load times   import  rxjs Rx     See this issue for more details

User · Answer

I tried below commands and it gets fixed   npm install rxjs 6 rxjs-compat 6 --save   import  rxjs Rx

User · Answer

Just some background    The newly minted Server Communication dev guide  finally  discusses mentions explains this   The RxJS library is quite large  Size matters when we build a production application and deploy it to mobile devices  We should include only those features that we actually need  Accordingly  Angular exposes a stripped down version of Observable in the rxjs Observable module  a version that lacks almost all operators including the ones we d like to use here such as the map method  It s up to us to add the operators we need  We could add each operator  one-by-one  until we had a custom Observable implementation tuned precisely to our requirements   So as  Thierry already answered  we can just pull in the operators we need  import  rxjs add operator map   import  rxjs operator delay   import  rxjs operator mergeMap   import  rxjs operator switchMap    Or  if we re lazy we can pull in the full set of operators  WARNING  this will add all 50  operators to your app bundle  and will effect load times import  rxjs Rx

User · Answer

Since Http service in angular2 returns an Observable type  From your Angular2 installation directory  node modules  in my case  We need to import map function of the Observable in your component using http service as   import  rxjs add operator map

User · Answer

Just add the line in you file   import  rxjs Rx    It will import bunch of dependencies Tested in angular 5

User · Answer

From rxjs 5 5 onwards  you can use the pipeable operators   import   map   from  rxjs operators     What is wrong with the import  rxjs add operator map    When we use this approach map operator will be patched to observable prototype  and becomes a part of this object    If later on  you decide to remove map operator from the code that handles the observable stream but fail to remove the corresponding import statement  the code that implements map remains a part of the Observable prototype   When the bundlers tries to eliminate the unused code  a k a  tree shaking   they may decide to keep the code of the  map operator in the Observable even though it   s not being used in the application   Solution - Pipeable operators  Pipeable operators are pure functions and do not patch the Observable  You can import operators using the ES6 import syntax import   map   from  rxjs operators  and then wrap them into a function pipe   that takes a variable number of parameters  i e  chainable operators   Something like this   getHalls         return this http get HallService PATH    hall json        pipe          map  res  Response    gt  res json

User · Answer

The map you using here  is not the  map   in javascript  it s Rxjs map function which working on Observables in Angular     So in that case you need to import it if you d like to use map on the result data        map project  function value  T  index  number   R  thisArg  any     Observable lt R gt  Applies a given project function to each value emitted   by the source Observable  and emits the resulting values as an   Observable    So simply import it like this   import  rxjs add operator map

User · Answer

Angular 6 - only import  rxjs Rx  did the trick for me

User · Answer

import   map   from  rxjs operators    this works for me in angular 8

[angular] Angular HTTP GET with TypeScript error http.get(...).map is not a function in [null]

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