Angular 4 http get with multiple params to Spring Request Mapping - spring

Question

I'm trying to send a httpClient.get request with params and consume it in my Spring Controller. I want to send search criteria and return a list of objects according to that criteria.
This is my search.service.ts
public getDentists(name, city, type, rating): Observable<Dentist[]>{
let params = new HttpParams();
params.set('name', name);
params.set('city', city);
params.set('type', type);
params.set('rating', rating);
return this.httpClient.get('dentists/', {params: params});
}
in my controller.java
#RequestMapping(value = "/dentists", method = RequestMethod.GET)
public List<Dentist> search(#RequestParam("name") String name,
#RequestParam("city") String city,
#RequestParam("type") String type,
#RequestParam("rating") String rating) {
return dentistRepository.findDentistByName(name);
}
This is what I get as an error:
I also get this error:
2017-12-03 01:07:10.138 WARN 10108 --- [nio-8080-exec-1] .w.s.m.s.DefaultHandlerExceptionResolver : Resolved exception caused by Handler execution: org.springframework.web.bind.MissingServletRequestParameterException: Required String parameter 'name' is not present
My question is what am I doing wrong, why am I not receiving the params with requestparam?

Answer 1

HttpParams is immutable. All the mutation operators return a new instance, so you have to do
let params = new HttpParams()
.set('name', name)
.set('city', city)
.set('type', type)
.set('rating', rating);
or
let params = new HttpParams();
params = params.set('name', name);
params = params.set('city', city);
params = params.set('type', type);
params = params.set('rating', rating);

Answer 2

change your code to:
let params = new HttpParams()
.set('name', name)
.set('city', city)
.set('type', type)
.set('rating', rating);
HttpParams is immutable.

Answer 3

try to use append() method (instead of add()):
public getDentists(name, city, type, rating): Observable<Dentist[]>{
let params = new HttpParams();
params = params.append('name', name);
params = params.append('city', city);
params = params.append('type', type);
params = params.append('rating', rating);
return this.httpClient.get('dentists/', {params: params});
}
UPDATE
actually append() and set() methods will produce exactly the same result:
?name=NAME_VALUE&city-CITY_VALUE&type=TYPE_VALUE&rating=RATING_VALUE,
append() should be used when we want to append another value to existing key, something like:
?name=NAME1&name=NAME2_VALUE&.....
We also can use HttpParamsOptions object passed to HttpParams constructor:
const params = new HttpParams({
fromObject: {
name,
city,
type,
rating
}
});
return this.httpClient.get('dentists/', {params});