Jackson with JSON Unrecognized field not marked as ignorable

Question

I need to convert a certain JSON string to a Java object  I am using Jackson for JSON handling  I have no control over the input JSON  I read from a web service   This is my input JSON     wrapper     id   13   name   Fred       Here is a simplified use case   private void tryReading         String jsonStr       wrapper        id     13     name     Fred            ObjectMapper mapper   new ObjectMapper          Wrapper wrapper   null      try           wrapper   mapper readValue jsonStr   Wrapper class         catch  Exception e            e printStackTrace              System out println  wrapper       wrapper       My entity class is   public Class Student        private String name      private String id        getters  amp  setters for name  amp  id here     My Wrapper class is basically a container object to get my list of students   public Class Wrapper       private List lt Student gt  students        getters  amp  setters here     I keep getting this error and  wrapper  returns null  I am not sure what s missing  Can someone help please   org codehaus jackson map exc UnrecognizedPropertyException       Unrecognized field  wrapper   Class Wrapper   not marked as ignorable  at  Source  java io StringReader 1198891  line  1  column  13        through reference chain  Wrapper  wrapper     at org codehaus jackson map exc UnrecognizedPropertyException      from UnrecognizedPropertyException java 53

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The new Firebase Android introduced some huge changes   below the copy of the doc     https   firebase google com support guides firebase-android      Update your Java model objects  As with the 2 x SDK  Firebase Database will automatically convert Java objects that you pass to DatabaseReference setValue   into JSON and can read JSON into Java objects using DataSnapshot getValue     In the new SDK  when reading JSON into a Java object with DataSnapshot getValue    unknown properties in the JSON are now ignored by default so you no longer need  JsonIgnoreExtraProperties ignoreUnknown true    To exclude fields getters when writing a Java object to JSON  the annotation is now called  Exclude instead of  JsonIgnore   BEFORE   JsonIgnoreExtraProperties ignoreUnknown true  public class ChatMessage      public String name     public String message      JsonIgnore    public String ignoreThisField     dataSnapshot getValue ChatMessage class      AFTER  public class ChatMessage      public String name     public String message      Exclude    public String ignoreThisField     dataSnapshot getValue ChatMessage class    If there is an extra property in your JSON that is not in your Java class  you will see this warning in the log files   W ClassMapper  No setter field for ignoreThisProperty found on class com firebase migrationguide ChatMessage   You can get rid of this warning by putting an  IgnoreExtraProperties annotation on your class  If you want Firebase Database to behave as it did in the 2 x SDK and throw an exception if there are unknown properties  you can put a  ThrowOnExtraProperties annotation on your class

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You can use Jackson s class-level annotation   import com fasterxml jackson annotation JsonIgnoreProperties   JsonIgnoreProperties class            It will ignore every property you haven t defined in your POJO  Very useful when you are just looking for a couple of properties in the JSON and don t want to write the whole mapping  More info at Jackson s website  If you want to ignore any non declared property  you should write    JsonIgnoreProperties ignoreUnknown   true

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If you are using Jackson 2 0   ObjectMapper mapper   new ObjectMapper    mapper disable DeserializationFeature FAIL ON UNKNOWN PROPERTIES

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it can be achieved 2 ways    Mark the POJO to ignore unknown properties   JsonIgnoreProperties ignoreUnknown   true   Configure ObjectMapper that serializes De-serializes the POJO json as below   ObjectMapper mapper  new ObjectMapper                   for Jackson version 1 X         mapper configure DeserializationConfig Feature FAIL ON UNKNOWN PROPERTIES  false      for Jackson version 2 X mapper configure DeserializationFeature FAIL ON UNKNOWN PROPERTIES  false

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In my case error came due to following reason   Initially it was working fine then i renamed one variable made the changes in code and it gave me this error  Then i applied jackson ignorant property also but it did not work  Finally after re defining my getters and setters methods according to name of my variable this error was resolved   So make sure to redifine getters and setters also

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set public your class fields not private   public Class Student        public String name      public String id        getters  amp  setters for name  amp  id here

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The first answer is almost correct  but what is needed is to change getter method  NOT field -- field is private  and not auto-detected   further  getters have precedence over fields if both are visible  There are ways to make private fields visible  too  but if you want to have getter there s not much point   So getter should either be named getWrapper    or annotated with    JsonProperty  wrapper     If you prefer getter method name as is

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This worked perfectly for me   objectMapper configure DeserializationFeature FAIL ON UNKNOWN PROPERTIES  false

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Your input     wrapper     id   13   name   Fred       indicates that it is an Object  with a field named  wrapper   which is a Collection of Students  So my recommendation would be   Wrapper   mapper readValue jsonStr   Wrapper class     where Wrapper is defined as  class Wrapper       List lt Student gt  wrapper

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It worked for me with the following code   ObjectMapper mapper  new ObjectMapper        mapper configure DeserializationConfig Feature FAIL ON UNKNOWN PROPERTIES  false

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Either Change   public Class Wrapper       private List lt Student gt  students        getters  amp  setters here     to   public Class Wrapper       private List lt Student gt  wrapper        getters  amp  setters here     ---- or ----  Change your JSON string to     students     id   13   name   Fred

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I have tried the below method and it works for such JSON format reading with Jackson  Use the already suggested solution of  annotating getter with  JsonProperty  wrapper    Your wrapper class  public Class Wrapper     private List lt Student gt  students      getters  amp  setters here       My Suggestion of wrapper class  public Class Wrapper      private StudentHelper students        getters  amp  setters here       Annotate getter    JsonProperty  wrapper     StudentHelper getStudents         return students             public class StudentHelper       JsonProperty  Student     public List lt Student gt  students        CTOR  getters and setters     NOTE  If students is private annotate getter with the annotation  JsonProperty  Student       This would however give you the output of the format     wrapper    student     id  13  name  Fred       Also for more information refer to https   github com FasterXML jackson-annotations   Hope this helps

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Google brought me here and i was surprised to see the answers    all suggested bypassing the error   which always bites back 4 folds later in developement   rather than solving it until this gentleman restored by faith in SO   objectMapper readValue responseBody  TargetClass class    is used to convert a json String to an class object  whats missing is that the TargetClass should have public getter   setters  Same is missing in OP s question snippet too      via lombok your class as below should work     Data  Builder public class TargetClass       private String a

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In my case a I have to add public getters and setters to leave fields private   ObjectMapper mapper   new ObjectMapper    Application application   mapper readValue input  Application class     I use jackson-databind 2 10 0 pr3

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import com fasterxml jackson annotation JsonIgnoreProperties    JsonIgnoreProperties

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What worked for me  was to make the property public  It solved the problem for me

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If for some reason you cannot add the  JsonIgnoreProperties annotations to your class and you are inside a web server container such as Jetty  You can create and customize the ObjectMapper inside a custom provider import javax ws rs ext ContextResolver  import javax ws rs ext Provider   import com fasterxml jackson annotation JsonInclude Include  import com fasterxml jackson databind DeserializationFeature  import com fasterxml jackson databind ObjectMapper    Provider public class CustomObjectMapperProvider implements ContextResolver lt ObjectMapper gt         private ObjectMapper objectMapper        Override     public ObjectMapper getContext final Class lt   gt  cls            return getObjectMapper               private synchronized ObjectMapper getObjectMapper             if objectMapper    null                objectMapper   new ObjectMapper                objectMapper configure DeserializationFeature FAIL ON UNKNOWN PROPERTIES  false                     return objectMapper

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The shortest solution without setter getter is to add  JsonProperty to a class field  public class Wrapper        JsonProperty     private List lt Student gt  wrapper     public class Student        JsonProperty     private String name       JsonProperty     private String id     Also  you called students list  quot wrapper quot  in your json  so Jackson expects a class with a field called  quot wrapper quot

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In my case it was simple  the REST-service JSON Object was updated  a property was added   but the REST-client JSON Object wasn t  As soon as i ve updated JSON client object the  Unrecognized field      exception has vanished

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This just perfectly worked for me     ObjectMapper objectMapper   new ObjectMapper    objectMapper configure      DeserializationConfig Feature FAIL ON UNKNOWN PROPERTIES  false      JsonIgnoreProperties ignoreUnknown   true  annotation did not

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Jackson is complaining because it can t find a field in your class Wrapper that s called  wrapper    It s doing this because your JSON object has a property called  wrapper    I think the fix is to rename your Wrapper class s field to  wrapper  instead of  students

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You can use  ObjectMapper objectMapper   getObjectMapper    objectMapper configure DeserializationFeature FAIL ON UNKNOWN PROPERTIES  false     It will ignore all the properties that are not declared

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This solution is generic when reading json streams and need to get only some fields while fields not mapped correctly in your Domain Classes can be ignored   import org codehaus jackson annotate JsonIgnoreProperties   JsonIgnoreProperties ignoreUnknown   true    A detailed solution would be to use a tool such as   jsonschema2pojo to autogenerate the required Domain Classes such as Student from the Schema of the json Response  You can do the latter by any online json to schema converter

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This may be a very late response  but just changing the POJO to this should solve the json string provided in the problem  since  the input string is not in your control as you said    public class Wrapper       private List lt Student gt  wrapper        getters  amp  setters here

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Your json string is not inline with the mapped class  Change the input string  String jsonStr       students        id     13     name     Fred          Or change your mapped class  public class Wrapper       private List lt Student gt  wrapper        getters  amp  setters here

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using Jackson 2 6 0  this worked for me   private static final ObjectMapper objectMapper        new ObjectMapper            configure DeserializationFeature FAIL ON UNKNOWN PROPERTIES  false     and with setting    JsonIgnoreProperties ignoreUnknown   true

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According to the doc you can ignore selected fields or all uknown fields       to prevent specified fields from being serialized or deserialized      i e  not include in JSON output  or being set even if they were included    JsonIgnoreProperties    internalId    secretKey          To ignore any unknown properties in JSON input without exception    JsonIgnoreProperties ignoreUnknown true

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You should just change the field of List from  students  to  wrapper  just the json file and the mapper will look it up

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Change Wrapper class to  public Class Wrapper               JsonProperty  wrapper       add this line           private List lt Student gt  students      What this does is to recognise the students field as wrapper key of the json object   Also I personally prefer using Lombok Annotations for Getters and Setters as   Getter  Setter public Class Wrapper               JsonProperty  wrapper       add this line           private List lt Student gt  students      Since I have not tested the above code with Lombok and  JsonProperty together  I ll suggest you to add the following code to Wrapper class as well to override Lombok s default getter and setter   public List lt Student gt  getWrapper         return students     public void setWrapper List lt Student gt  students        this students   students      Also check this out to deserialise lists using Jackson

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One other possibility is this property in the application properties spring jackson deserialization fail-on-unknown-properties false  which won t need any other code change in your application  And when you believe the contract is stable  you can remove this property or mark it true

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When we are generating getters and setters  specially which starts with  is  keyword  IDE generally removes the  is   e g   private boolean isActive   public void setActive boolean active       isActive   active     public isActive       return isActive      In my case  i just changed the getter and setter   private boolean isActive   public void setIsActive boolean active       isActive   active     public getIsActive       return isActive      And it was able to recognize the field

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I fixed this problem by simply changing the signatures of my setter and getter methods of my POJO class  All I had to do was change the getObject method to match what the mapper was looking for  In my case I had a getImageUrl originally  but the JSON data had image url which was throwing the mapper off  I changed both my setter and getters to getImage url and setImage url   Hope this helps

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FAIL ON UNKNOWN PROPERTIES option is true by default   FAIL ON UNKNOWN PROPERTIES  default  true  Used to control whether encountering of unknown properties  one for which there is no setter  and there is no fallback  any setter  method defined using  JsonAnySetter annotation  should result in a JsonMappingException  when enabled   or just quietly ignored  when disabled

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Adding setters and getters solved the problem  what I felt is the actual issue was how to solve it but not how to suppress ignore the error  I got the error  Unrecognized field   not marked as ignorable     Though I use the below annotation on top of the class it was not able to parse the json object and give me the input      JsonIgnoreProperties ignoreUnknown   true    Then I realized that I did not add setters and getters  after adding setters and getters to the  Wrapper  and to the  Student  it worked like a charm

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You need to verify all fields of the class you are parsing in  make it the same as in your original JSONObject  It helped me and in my case    JsonIgnoreProperties ignoreUnknown   true  didn t help at all

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This may not be the same problem that the OP had but in case someone got here with the same mistake I had then this will help them solve their problem  I got the same error as the OP when I used an ObjectMapper from a different dependency as the JsonProperty annotation   This works   import com fasterxml jackson databind ObjectMapper  import com fasterxml jackson annotation JsonProperty    Does NOT work   import org codehaus jackson map ObjectMapper    org codehaus jackson jackson-mapper-asl 1 8 8 import com fasterxml jackson annotation JsonProperty    com fasterxml jackson core jackson-databind 2 2 3

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As no one else has mentioned  thought I would     Problem is your property in your JSON is called  wrapper  and your property in Wrapper class is called  students    So either      Correct the name of the property in either the class or JSON  Annotate your property variable as per StaxMan s comment  Annotate the setter  if you have one

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For my part  the only line    JsonIgnoreProperties ignoreUnknown   true   didn t work too   Just add    JsonInclude Include NON EMPTY    Jackson 2 4 0

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Somehow after 45 posts and 10 years  no one has posted the correct answer for my case   Data   Lombok public class MyClass       private int foo      private int bar        JsonIgnore     public int getFoobar           return foo   bar           In my case  we have a method called getFoobar    but no foobar property  because it s computed from other properties     JsonIgnoreProperties on the class does not work  The solution is to annotate the method with  JsonIgnore

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Annotate the field students as below since there is mismatch in names of json property and java property  public Class Wrapper        JsonProperty  wrapper       private List lt Student gt  students        getters  amp  setters here

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The POJO should be defined as  Response class  public class Response       private List lt Wrapper gt  wrappers         getter and setter     Wrapper class  public class Wrapper       private String id      private String name         getters and setters     and mapper to read value  Response response   mapper readValue jsonStr   Response class

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This works better than All please refer to this property   import com fasterxml jackson databind DeserializationFeature  import com fasterxml jackson databind ObjectMapper       ObjectMapper objectMapper   new ObjectMapper        objectMapper configure DeserializationFeature FAIL ON UNKNOWN PROPERTIES  false       projectVO   objectMapper readValue yourjsonstring  Test class

[java] Jackson with JSON: Unrecognized field, not marked as ignorable

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