No String-argument constructor factory method to deserialize from String value

Question

I m running into a json parsing issue when using the ObjectMapper class from the com fasterxml jackson databind package  and the error that I m getting is   com fasterxml jackson databind JsonMappingException  Can not construct instance of com graybar utilities ups beans Address  no String-argument constructor factory method to deserialize from String value        The web application where this problem is occurring is a Spring MVC application using an AngularJS front end  but I can duplicate the issue with a much smaller  all java program  Here are my beans   Shipment java   JsonIgnoreProperties ignoreUnknown   true  public class Shipment        JsonProperty  Activity       private ArrayList lt Activity gt  activity      public ArrayList lt Activity gt  getActivity             return activity            public void setActivity ArrayList lt Activity gt  activity            this activity   activity            Activity java   JsonIgnoreProperties ignoreUnknown   true  public class Activity        JsonProperty  ActivityLocation       private ArrayList lt ActivityLocation gt  activityLocation      public ArrayList lt ActivityLocation gt  getActivityLocation             return activityLocation            public void setActivityLocation ArrayList lt ActivityLocation gt  activityLocation            this activityLocation   activityLocation            ActivityLocation java   JsonIgnoreProperties ignoreUnknown   true  public class ActivityLocation        JsonProperty  Address       private Address address      public Address getAddress             return address            public void setAddress Address address            this address   address            Address java   JsonIgnoreProperties ignoreUnknown   true  public class Address        JsonProperty  City       private String city       JsonProperty  StateProvinceCode       private String stateProvinceCode       JsonProperty  CountryCode       private String countryCode      public String getCity             return city            public void setCity String city            this city   city            public String getCountryCode             return countryCode            public void setCountryCode String countryCode            this countryCode   countryCode            public String getStateProvinceCode             return stateProvinceCode            public void setStateProvinceCode String stateProvinceCode            this stateProvinceCode   stateProvinceCode            Here is the code where I can properly map the json   public static void main String   args        String jsonMessage                                     Activity                             ActivityLocation                                Address                                    City      Hana                                  StateProvinceCode      Hi                                  CountryCode      US                                                                                                              ActivityLocation                                Address                                    City      Honolulu                                  StateProvinceCode      Hi                                  CountryCode      US                                                                                         try           ObjectMapper mapper   new ObjectMapper            mapper enable DeserializationFeature ACCEPT SINGLE VALUE AS ARRAY            Shipment shipment   mapper readValue jsonMessage  Shipment class           System out println  shipment toString       shipment toString           catch  Exception e            e printStackTrace              When adjusting the data in the jsonMessage var is when I run into the error that I mentioned above                        Activity                         ActivityLocation                            Address                                City      Hana                              StateProvinceCode      Hi                              CountryCode      US                                                                                          ActivityLocation                            Address                                                                                So  the problem happens when changing the json from this          ActivityLocation               Address                  City    Honolulu                 StateProvinceCode    Hi                 CountryCode    US                       to this      ActivityLocation           Address                Instead of sending values for my Address bean  I m getting just an empty string  Unfortunately  I m receiving my data from a third party and have no control over the data I receive    Is there an annotation that needs to be added to be able to handle this

User · Answer

Use below code snippet This worked for me

ObjectMapper objectMapper = new ObjectMapper();
String jsonString = "{\"symbol\":\"ABCD\}";
objectMapper.configure(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT, true);
Trade trade = objectMapper.readValue(jsonString, new TypeReference<Symbol>() {});

Model Class

@JsonIgnoreProperties    public class Symbol {
    @JsonProperty("symbol")
    private String symbol;
}

User · Answer

Had this when I accidentally was calling   mapper convertValue        instead of   mapper readValue        So  just make sure you call correct method  since argument are same and IDE can find many things

User · Answer

I found a different way to handle this error   the variables is according to the original question       JsonNode parsedNodes   mapper readValue jsonMessage   JsonNode class           Response response   xmlMapper enable ACCEPT EMPTY STRING AS NULL OBJECT ACCEPT SINGLE VALUE AS ARRAY                    disable FAIL ON UNKNOWN PROPERTIES  FAIL ON IGNORED PROPERTIES                   convertValue parsedNodes  Response class

User · Answer

This exception says that you are trying to deserialize the object  Address  from string        instead of an object description like          The deserializer can t find a constructor of Address with String argument  You have to replace    by    to avoid this error

User · Answer

Try setting mapper configure DeserializationConfig Feature ACCEPT EMPTY STRING AS NULL OBJECT  true    or   mapper enable DeserializationFeature ACCEPT EMPTY STRING AS NULL OBJECT     depending on your Jackson version

User · Answer

mapper enable DeserializationFeature ACCEPT EMPTY STRING AS NULL OBJECT     My code work well just as the answer above  The reason is that the json from jackson is different with the json sent from controller   String test1  mapper writeValueAsString result1     And the json is like which can be deserialized normally      code  200  message   god   data     nics  null  status  null  desktopOperatorType  null  marker  null  user name  null  user group  null  user email  null  product id  null  image id  null  computer name   AAAA   desktop id  null  created  null  ip address  null  security groups  null  root volume  null  data volumes  null  availability zone  null  ou name  null  login status  null  desktop ip  null  ad id  null    nics  null  status  null  desktopOperatorType  null  marker  null  user name  null  user group  null  user email  null  product id  null  image id  null  computer name   BBBB   desktop id  null  created  null  ip address  null  security groups  null  root volume  null  data volumes  null  availability zone  null  ou name  null  login status  null  desktop ip  null  ad id  null      but the json send from the another service just like     code  200  message              data     nics      status      metadata      desktopOperatorType      marker      user name   csrgzbsjy   user group   ADMINISTRATORS   user email      product id      image id      computer name   B-jiegou-all-15   desktop id   6360ee29-eb82-416b-aab8-18ded887e8ff   created   2018-11-12T07 45 15 000Z   ip address   192 168 2 215   security groups      root volume      data volumes      availability zone      ou name      login status      desktop ip      ad id        nics      status      metadata      desktopOperatorType      marker      user name   glory 2147   user group   ADMINISTRATORS   user email      product id      image id      computer name   H-pkpm-all-357   desktop id   709164e4-d3e6-495d-9c1e-a7b82e30bc83   created   2018-11-09T09 54 09 000Z   ip address   192 168 2 235   security groups      root volume      data volumes      availability zone      ou name      login status      desktop ip      ad id          You can notice the difference when dealing with the param without initiation  Be careful

[java] No String-argument constructor/factory method to deserialize from String value ('')

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