CODEWITHSUNDEEP
javajsonjackson
user4649961
user4649961

Reputation:

Jackson library 1.x array if one element sometimes just a string

I have to deal with strange Json messages.

there are Arrays in the schema, but if there are only one element array becomes an string.

So sometimes it is:

        "Cisco-AVPair": [
            "connect-progress=Call Up", 
            "nas-tx-speed=8083000", 
            "nas-rx-speed=8083000"
        ],

and sometimes: 

         "Cisco-AVPair": "connect-progress=Call Up".

How to overcome this if I use Jackson 1.8.2

I am afraid I am not in control of source code generation and only can parse it.

I do parse it with:

         mapper.readValue(json, refType);

while my type reference is: 

         @JsonProperty("Cisco-AVPair")
         private List<String> CiscoAVPair = new ArrayList<String>();

         @JsonProperty("Cisco-AVPair")
         public List<String> getCiscoAVPair() {
         return CiscoAVPair;
         }

         @JsonProperty("Cisco-AVPair")
         public void setCiscoAVPair(List<String> CiscoAVPair) {
         this.CiscoAVPair = CiscoAVPair;
         }

As you see it is list of strings, but sometimes comes just as a string.

Upvotes: 3

Views: 808

Answers (1)

fps
fps

Reputation: 34460

There's a specific config option even in ancient Jackson 1.8.2 that accomplishes exactly what you need.

You should configure your ObjectMapper instance to always deserialize JSON values as a List, no matter whether values come as an array or as a single element. Please see javadocs here for the deserialization feature you need to enable, and these other javadocs to see how to actually activate/deactivate a feature on an ObjectMapper instance.

ObjectMapper mapper = ...;
mapper = mapper.configure(DeserializationConfig.Feature.ACCEPT_SINGLE_VALUE_AS_ARRAY, true);

Bear in mind that configure() method returns another instance of ObjectMapper.

Upvotes: 1

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