CODEWITHSUNDEEP
javaandroidjsonserializationjackson
Acrotygma
Acrotygma

Reputation: 2569

Map BasicNameValuePair from JSON with Jackson

I'm currently trying to deserialize an API result, which looks like the following

[{"name":"MyName","value":"MyValue"},{"name":"MyName2","value":"MyValue2"}]


ArrayList<BasicNameValuePair> entities = JsonUtils.getObjectMapper()
    .readValue(receivedData.toString(),
    new TypeReference<ArrayList<BasicNameValuePair>>() {});

Then the following exceptions occurs

Exception mapping result.
No suitable constructor found for type...

Since this is an internal class from org.apache.http.message.BasicNameValuePair, I can not annotate or edit it in any way. But I see (from other android projects) a lot of people using this class. Is there some way to get this working? Serializing to String from BasicNameValuePair works.

Upvotes: 1

Views: 813

Answers (2)

Sotirios Delimanolis
Sotirios Delimanolis

Reputation: 279880

Jackson uses reflection to create an instance of your class. By default, it expects a no-arg constructor. The BasicNameValuePair class does not have such a constructor. It has a constructor with two parameters, one for name and one for value.

Typically, if you had control of the class, you could annotate the constructor parameters with @JsonProperty so that Jackson used that constructor instead of the no-arg constructor. Since you don't have control of the code, use Mixins.

Declare a class like so

public static abstract class BasicNameValuePairMixIn {
     private BasicNameValuePairMixIn(@JsonProperty("name") String name, @JsonProperty("value") String value) { }
}

And configure your ObjectMapper like so

// configuration for Jackson/fasterxml 
objectMapper.addMixInAnnotations(BasicNameValuePair.class, BasicNameValuePairMixIn.class);

Jackson will now use the mixin as a template for your class.

If you are using the older version of Jackson, use the configuration as described here.

Upvotes: 3

UMAR-MOBITSOLUTIONS
UMAR-MOBITSOLUTIONS

Reputation: 77984

Try not to use reserve keywords in your parameter names and then try again. "name","value"

Upvotes: -2

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