passing optional query string parameters to http service call

Question

i need to make an API call which allows me to pass through optional query sting params

 retrieveConts(param1:string,param2?:string):Observable<IContracts> {  
  this.basePath =  "/myConts"; 
      return http.get(this.basePath,{ 
      params: {  
       arg1:param1,
       arg2:param2,
      },
      withCredentials: false
    }) 
     .catch(this._errorHandler); 
  }

With the above code spinet, i have declared param2 as an optional parameter which can or cannot be passed through to the service call, however if param2 gets no value, it then returns undefined for which its understandable.

How do i make the service call to ignore the "arg2" parameter if no value was returned from the param2 variable?

Milos Kovacevic · Accepted Answer · 2018-05-28 11:01:16Z

6

You can do something like this:

retrieveConts(param1:string,param2?:string):Observable<IContracts> {  
    this.basePath =  "/myConts"; 
    let params = {arg1: param1};
    if (param2)
        params = {arg1: param1, arg2: param2};

    return http.get(this.basePath, { 
        params: params,
        withCredentials: false
    }) 
    .catch(this._errorHandler); 
}

Hope this will be helpful!

answered May 28, 2018 at 11:01

Milos Kovacevic

9011 gold badge9 silver badges21 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Thomsheer Ahamed · Accepted Answer · 2018-06-01 02:58:08Z

instead of passing two values in component, you could pass a object

//Assuming userService is your service // code in your component

userService.retrieveConts({arg1:"val1",arg2:"val2"})

// Code in userService

retrieveConts(param:any):Observable<IContracts> {  
  this.basePath =  "/myConts"; 
      return http.get(this.basePath,{ 
      params: param,
      withCredentials: false
    }) 
     .catch(this._errorHandler); 
  }

or you can also check for param2 and append it to object

retrieveConts(param1:string,param2?:string):Observable<IContracts> {  
    this.basePath =  "/myConts"; 
    let params = {arg1: param1};
    if (param2) params.arg2 = param2;

        return http.get(this.basePath, { 
            params: params,
            withCredentials: false
        }) 
        .catch(this._errorHandler); 
    }

or pass empty val, if param2 is undefined or null

retrieveConts(param1:string,param2?:string):Observable<IContracts> {  
        this.basePath =  "/myConts"; 

            return http.get(this.basePath, { 
                params: {arg1: param1, arg2: param2 || ''},
                withCredentials: false
            }) 
            .catch(this._errorHandler); 
        }

or

  retrieveConts(param1:string,param2?:string=""):Observable<IContracts> {
           this.basePath =  "/myConts"; 

            return http.get(this.basePath, { 
                params: {arg1: param1, arg2: param2},
                withCredentials: false
            }) 
            .catch(this._errorHandler); 
        }

V Djuric · Accepted Answer · 2019-04-02 09:01:19Z

1

You can try something like this:

retrieveConts(p1,p2?): Observable<IContracts> {
    this.basePath =  "/myConts";
    let params = {argument1: p1};
    if (p2)
        params = {argument1: p1, argument2: p2};

    return http.get(this.basePath, {
        params: params,
        withCredentials: false
    })
    .catch(this._errorHandler);
 }

answered Apr 2, 2019 at 9:01

V Djuric

715 bronze badges

1 Comment

mooga Over a year ago

It would be nice if you add some explanation to your code

user4676340 · Accepted Answer · 2018-05-28 11:03:10Z

0

Switch to an object definition to shorten your code (other solutions will make it longer) :

retrieveConts(params: { [key: string]: value: string }) {
  return http
    .get('/myConts', { 
      params,
      withCredentials: false
    }) 
    .catch(this._errorHandler); 
}

The argument is declared as an object that can has a string key with a string value, and you pass it directly as the params of your URL (properties with the same name don't need to be written twice)

answered May 28, 2018 at 11:03

user4676340

1 Comment

Abijith Ajayan Over a year ago

But from this solution, Am passing more than 7 params, That time some of them are optional, but from this HTTPPARAMS, every time its passing complete params with undefined values.

Fernando Raposo · Accepted Answer · 2020-11-03 20:36:29Z

0

I would suggest one minor change: Instead of:

    this.basePath =  "/myConts"; 
    let params = {arg1: param1};
    if (param2) params.arg2 = param2;

        return http.get(this.basePath, { 
            params: params,
            withCredentials: false
        }) 
        .catch(this._errorHandler); 
    }

I would do:

        this.basePath =  "/myConts"; 
    let params = {arg1: param1};
    if (param2) params['arg2'] = param2;

        return http.get(this.basePath, { 
            params: params,
            withCredentials: false
        }) 
        .catch(this._errorHandler); 
    }

By doing this you will avoid compilation error in Angular for instance.

answered Nov 3, 2020 at 20:36

Fernando Raposo

514 bronze badges

Comments

Daniel Rojas Rodriguez · Accepted Answer · 2021-09-04 15:13:41Z

0

You can try something like this:

retrieveConts(param1:string,param2?:string):Observable<IContracts> {  
     var params = {arg1:param1};

     if(param2){
         params = Object.assign(params,{arg2:param2})
     }

     this.basePath =  "/myConts"; 
         return http.get(this.basePath,{ 
         params: params,
         withCredentials: false
     }).catch(this._errorHandler); 
 }

answered Sep 4, 2021 at 15:13

Daniel Rojas Rodriguez

412 bronze badges

Collectives™ on Stack Overflow

passing optional query string parameters to http service call

6 Answers 6

Comments

Comments

1 Comment

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

6 Answers 6

Comments

Comments

1 Comment

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related