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POCan not deserialize instance of java.util.ArrayList out of VALUE_STRING
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  1. POCan not deserialize instance of java.util.ArrayList out of VALUE_STRING
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    copied!<p>I have a REST service built with Jersey and deployed in the AppEngine. The REST service implements the verb PUT that consumes an application/json media type. The data binding is performed by Jackson.</p> <p>The verb consumes an enterprise-departments relation represented in JSON as </p> <pre><code>{"name":"myEnterprise", "departments":["HR","IT","SC"]} </code></pre> <p>In the client side, I use gson to convert the JSON representation into a java object. Then, I pass the object to my REST service and it works fine.</p> <p><strong>Problem:</strong></p> <p>When my JSON representation has only one item in the collection</p> <pre><code>{"name":"myEnterprise", "departments":["HR"]} </code></pre> <p>the service cannot deserialize the object.</p> <pre><code>ATTENTION: /enterprise/enterprise: org.codehaus.jackson.map.JsonMappingException: Can not deserialize instance of java.util.ArrayList out of VALUE_STRING token at [Source: org.mortbay.jetty.HttpParser$Input@5a9c5842; line: 1, column: 2 </code></pre> <p>As reported by other users, the solution is to add the flag ACCEPT_SINGLE_VALUE_AS_ARRAY (e.g., <a href="https://stackoverflow.com/questions/14319573/jersey-can-not-deserialize-instance-of-arraylist-out-of-string">Jersey: Can not deserialize instance of ArrayList out of String</a>). Nevertheless, I am not controlling an ObjectMapper because in the service side it is transparently made by Jackson.</p> <p><strong>Question:</strong></p> <p>Is there a way to configure the ObjectMapper on the service side to enable ACCEPT_SINGLE_VALUE_AS_ARRAY? annotations? web.xml?</p> <p><strong>Code details</strong></p> <p>Java object:</p> <pre><code>@XmlRootElement public class Enterprise { private String name; private List&lt;String&gt; departments; public Enterprise() {} public String getName() { return name; } public void setName(String name) { this.name = name; } public List&lt;String&gt; getDepartments() { return departments; } public void setDepartments(List&lt;String&gt; departments) { this.departments = departments; } } </code></pre> <p>The REST service side:</p> <pre><code> @PUT @Consumes(MediaType.APPLICATION_JSON) @Produces(MediaType.APPLICATION_JSON) @Path("/enterprise") public Response putEnterprise(Enterprise enterprise, @Context HttpServletRequest req){ ... } </code></pre> <p>Client side:</p> <pre><code>... String jsonString = "{\"name\":\"myEnterprise\", \"departments\":[\"HR\"]}"; Enterprise enterprise = gson.fromJson(jsonString, Enterprise.class); System.out.println(gson.toJson(enterprise)); response = webResource .type(MediaType.APPLICATION_JSON) .put(ClientResponse.class,enterprise); if (response.getStatus() &gt;= 400) { throw new RuntimeException("Failed : HTTP error code : " + response.getStatus()); } ... </code></pre>
 

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