Facebook API Question posted in
The official documentation for the Facebook APIs can be found here.

Spring Webclient : illegalargumentexception not enough variables to expand 'comment_count'

I am using spring webclient to make a Facebook graph api request with url containing {comment_count}

But, getting this exception 

java.lang.IllegalArgumentException: Not enough variable values available to expand reactive spring

Code Snippet : 

import org.springframework.stereotype.Component;
import org.springframework.web.reactive.function.client.WebClient;

import reactor.core.publisher.Mono;

@Component
public class Stackoverflow {

    WebClient client = WebClient.create();

    public Mono<Post> fetchPost(String url) {
        // Url contains "comments{comment_count}"
        return client.get().uri(url).retrieve()
                .bodyToMono(Post.class);
    }
}

I know the solution with resttemplate, But i need to use spring webclient.

Tags:

2

Answers


  1. 0

    You can create your URL using UriComponentsBuilder as follows

     webClient.get().uri(getFacebookGraphURI(3)).retrieve().bodyToMono(Object.class);

private URI getFacebookGraphURI(int comments){
   return UriComponentsBuilder.fromHttpUrl("https://graph.facebook.com")
        .pathSegment("v3.2", "PAGE_ID", "posts").queryParam("fields", "comments{comment_count}")
        .queryParam("access_token", "acacaaac").build(comments);

  }

    OR

    int commentsCount = 3; webClient.get().uri(UriComponentsBuilder.fromHttpUrl(“https://graph.facebook.com“)
    .pathSegment(“v3.2”, “PAGE_ID”, “posts”).queryParam(“fields”, “comments{comment_count}”)
    .queryParam(“access_token”, “acacaaac”).build().toString(),commentsCount).retrieve().bodyToMono(Object.class);

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  2. 0

    The solution I use is to disable the encoding in DefaultUriBuilderFactory

    val urlBuilderFactory = DefaultUriBuilderFactory("https://foo.bar.com").apply {
    encodingMode = EncodingMode.NONE
}

val wc = wcb
    .clone()
    .uriBuilderFactory(urlBuilderFactory)
    .build()

    It’s in Kotlin, in Java you just have to use DefaultUriBuilderFactory#setEncodingMode(EncodingMode) with NONE as parameter.

    Due to this change of behavior, you have to encode your query params yourself. To do so, I use the

    val query = URLEncoder.encode(query_as_string, StandardCharsets.UTF_8.toString())

    And I can perform call like this:

    wc.get()
    .uri { it
        .path(graphqlEndpoints)
        .queryParam("variables", query)
        .build()
    }
    .retrieve()
    .bodyToFlux<String>()
    // ...

    For Java (as per comment by Anurag below) it will be something like this:

    var uriBuilderFactory = new DefaultUriBuilderFactory(baseUrl);   
uriBuilderFactory.setEncodingMode(DefaultUriBuilderFactory.EncodingMode.NONE);

var wc = WebClient.builder()
    .baseUrl(baseUrl) 
    .uriBuilderFactory(uriBuilderFactory)
    // ... other options
    .build(); 

wc.get()
     .uri(uriBuilder -> uriBuilder
         .path(path)
         // value still needs to be URL-encoded as needed (e.g., if value is a JSON
         .queryParam("param", value))
         .build())
     .retrieve()
     .bodyToMono(...);

    As noted above, you will still need to URL-encode the parameter value. With this approach, you are merely avoiding "double URL encoding" by replacing the urlBuilderFactory.

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