how to get the first list item from a json response using the spring webclient - Stack Overflow

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I am getting below response in rest API and want to parse and return the first list item using the spring webclient.

JSON Response

{"_embedded":{"service":[{"id":101,"serviceModelUUID":"aaa8884883","action":"create"},{"id":102,"serviceModelUUID":"aaa8884884","action":"delete"}]}}

I want to return below response

[{"id":101,"serviceModelUUID":"aaa8884883","action":"create"},{"id":102,"serviceModelUUID":"aaa8884884","action":"delete"}]

below is my spring webclient code which is returning single list with null field values

private <T> List<T> getMultipleResources(Class<T> clazz, URI uri) {
    return webClient.get().uri(uri).retrieve().bodyToFlux(clazz).collectList().block();
}

I am getting below response in rest API and want to parse and return the first list item using the spring webclient.

JSON Response

{"_embedded":{"service":[{"id":101,"serviceModelUUID":"aaa8884883","action":"create"},{"id":102,"serviceModelUUID":"aaa8884884","action":"delete"}]}}

I want to return below response

[{"id":101,"serviceModelUUID":"aaa8884883","action":"create"},{"id":102,"serviceModelUUID":"aaa8884884","action":"delete"}]

below is my spring webclient code which is returning single list with null field values

private <T> List<T> getMultipleResources(Class<T> clazz, URI uri) {
    return webClient.get().uri(uri).retrieve().bodyToFlux(clazz).collectList().block();
}

• spring
• spring-rest
• spring-webclient

Share Improve this question Follow asked Mar 13 at 8:45 Rajesh KumarRajesh Kumar 35133 silver badges1919 bronze badges

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1 Answer 1

Sorted by: Reset to default 1

Unpack needed field from your initial response and use constructParametricType to have JavaType for a list of instances of the passed Class<T>

A wrapper around the data you need. Here, you extract only the required field (_embedded.service).

class DataWrapper {
    private Object data;

    public Object getData() {
        return data;
    }

    @JsonProperty("_embedded")
    private void unpackEmbedded(Map<String, Object> embedded) {
        this.data = embedded.get("service");
    }
}

And construct JavaType to specify the expected data type returned by the endpoint.

private void howToUse() {
    List<Service> res1 = getMultipleResources(URI.create("/"), Service.class);
    // prints for your example
    // [{id=101, serviceModelUUID=aaa8884883, action=create}, {id=102, serviceModelUUID=aaa8884884, action=delete}]
    System.out.println(res1);
    // create
    System.out.println(res1.getFirst().getAction());
}

private <T> List<T> getMultipleResources(URI uri, Class<T> clazz) {
    var wrapperRef = new ParameterizedTypeReference<DataWrapper>() {};
    var data = webClient.get().uri(uri).retrieve().bodyToMono(wrapperRef).block().getData();
    // better to make an objectMapper as a property of service where getMultipleResources is defined
    var objectMapper = new ObjectMapper();
    var dataType = objectMapper.getTypeFactory().constructParametricType(List.class, clazz);
    return objectMapper.convertValue(data, dataType);
}

Dont fet to define you class - Service

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