How to fetch data using RestTemplate in Spring

Question

My task is writting a code to fetch data from rest API via URL like this

curl -k -v -XPOST -H "username: password" -H "Content-type: application/json" http://localhost:8181/api/rest/person/query -d '
    {
        "name": "person's name",
        "role": "role code",
        "programme": "programme code"
    }'

And here's my code

   public JsonUser fetchJsonUserByName(String name) throws IOException{
       String jsonName = "'{'name': "+"'"+name+"'}'";
       String url = "/person/query -d "+jsonName;
       ResponseEntity<JsonUser> response = restTemplate.getForEntity(url, JsonUser.class);
           try {
            if(response.hasBody()) return response.getBody();
               else return null;
        } catch (HttpStatusCodeException e) {
            if(e.getStatusCode() == HttpStatus.NOT_FOUND) return null;
            throw new IOException("error fetching user", e);
        } catch (Exception e) {
            throw new IOException("error fetching user", e);
        }
   }

And I got the error code 500 when I run my code, where was I wrong?

score 2 · Accepted Answer · answered Feb 12 '17 at 14:00

2

First of all this there is nothing about Spring Integration in this question. Please, be careful with tags selection in the future.

Your mistake here that you are missing the part that you use POST HTTP method with the curl. But with the RestRemplate you choose GET:

/**
 * Retrieve an entity by doing a GET on the specified URL.
 * The response is converted and stored in an {@link ResponseEntity}.
 * <p>URI Template variables are expanded using the given URI variables, if any.
 * @param url the URL
 * @param responseType the type of the return value
 * @param uriVariables the variables to expand the template
 * @return the entity
 * @since 3.0.2
 */
<T> ResponseEntity<T> getForEntity(String url, Class<T> responseType, Object... uriVariables) throws RestClientException;

Somehow I guess you meant this:

/**
 * Create a new resource by POSTing the given object to the URI template,
 * and returns the response as {@link ResponseEntity}.
 * <p>URI Template variables are expanded using the given URI variables, if any.
 * <p>The {@code request} parameter can be a {@link HttpEntity} in order to
 * add additional HTTP headers to the request.
 * @param url the URL
 * @param request the Object to be POSTed (may be {@code null})
 * @param uriVariables the variables to expand the template
 * @return the converted object
 * @since 3.0.2
 * @see HttpEntity
 */
<T> ResponseEntity<T> postForEntity(String url, Object request, Class<T> responseType, Object... uriVariables)
        throws RestClientException;

answered Feb 12 '17 at 14:00

Artem Bilan

113,505
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Thanks for your reply. I will be careful in next questions. – Thịnh Kều Feb 12 '17 at 15:13
1

Btw, `-d` is curl option. In case of post via `RestTemplate` you have to move your `jsonName` into that `request` argument . Right now your URL isn't correct – Artem Bilan Feb 12 '17 at 15:46
Thanks again for your useful infomation. I also guess the reason about my URL. – Thịnh Kều Feb 12 '17 at 15:54
Is it right?! ResponseEntity response = restTemplate.postForEntity(url,JsonUser.class,responseType,jsonName); – Thịnh Kều Feb 12 '17 at 16:00
No, your `jsonName` is request body, not paeans. Please read about HTTP protocol more – Artem Bilan Feb 12 '17 at 16:02
Right! i'm so noob bro. Post method retrieve data from "back-end", not via URL. – Thịnh Kều Feb 12 '17 at 16:43
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/135622/discussion-between-thnh-ku-and-artem-bilan). – Thịnh Kều Feb 13 '17 at 18:33

score 1 · Answer 2 · answered Feb 12 '17 at 14:00

1

Please confer to HTTP response codes, explained, where you will see that 500 means “I fucked up”, and that is the server’s point of view. It’s a server error, not yours.

Of course, the server error may be caused by malformed input such as you sending the totally wrong URL /person/query -d '{'name': 'name'}'.

answered Feb 12 '17 at 14:00

Michael Piefel

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I've tested manually by using command in Terminal and server still worked correctly with this input type '{'name': 'name'}' . So difficult to understand why code not working. – Thịnh Kều Feb 12 '17 at 15:17
1

The problem is not that it is the wrong parameter, but that you put it in the URL instead of the body. The other answer made that sufficiently clear. – Michael Piefel Feb 12 '17 at 17:29

How to fetch data using RestTemplate in Spring

2 Answers2