From 4ef931f67aa74c105276332722e2c68bf5fcd9ba Mon Sep 17 00:00:00 2001 From: Azhwani <13301425+azhwani@users.noreply.github.com> Date: Tue, 28 Feb 2023 06:11:01 +0100 Subject: [PATCH] BAEL-6076: Resolving Jackson JsonMappingException: Can not deserialize instance of java.lang.String out of START_OBJECT token (#13495) --- .../java/com/baeldung/exceptions/Contact.java | 15 +++++++++ .../java/com/baeldung/exceptions/Person.java | 33 +++++++++++++++++++ .../baeldung/exceptions/PersonContact.java | 33 +++++++++++++++++++ .../exceptions/JacksonExceptionsUnitTest.java | 33 ++++++++++++++++--- 4 files changed, 109 insertions(+), 5 deletions(-) create mode 100644 jackson-modules/jackson-exceptions/src/main/java/com/baeldung/exceptions/Contact.java create mode 100644 jackson-modules/jackson-exceptions/src/main/java/com/baeldung/exceptions/Person.java create mode 100644 jackson-modules/jackson-exceptions/src/main/java/com/baeldung/exceptions/PersonContact.java diff --git a/jackson-modules/jackson-exceptions/src/main/java/com/baeldung/exceptions/Contact.java b/jackson-modules/jackson-exceptions/src/main/java/com/baeldung/exceptions/Contact.java new file mode 100644 index 0000000000..6417d60310 --- /dev/null +++ b/jackson-modules/jackson-exceptions/src/main/java/com/baeldung/exceptions/Contact.java @@ -0,0 +1,15 @@ +package com.baeldung.exceptions; + +public class Contact { + + private String email; + + public String getEmail() { + return email; + } + + public void setEmail(String email) { + this.email = email; + } + +} diff --git a/jackson-modules/jackson-exceptions/src/main/java/com/baeldung/exceptions/Person.java b/jackson-modules/jackson-exceptions/src/main/java/com/baeldung/exceptions/Person.java new file mode 100644 index 0000000000..1572d7a71f --- /dev/null +++ b/jackson-modules/jackson-exceptions/src/main/java/com/baeldung/exceptions/Person.java @@ -0,0 +1,33 @@ +package com.baeldung.exceptions; + +public class Person { + + private String firstName; + private String lastName; + private String contact; + + public String getFirstName() { + return firstName; + } + + public void setFirstName(String firstName) { + this.firstName = firstName; + } + + public String getLastName() { + return lastName; + } + + public void setLastName(String lastName) { + this.lastName = lastName; + } + + public String getContact() { + return contact; + } + + public void setContact(String contact) { + this.contact = contact; + } + +} diff --git a/jackson-modules/jackson-exceptions/src/main/java/com/baeldung/exceptions/PersonContact.java b/jackson-modules/jackson-exceptions/src/main/java/com/baeldung/exceptions/PersonContact.java new file mode 100644 index 0000000000..0c75240d94 --- /dev/null +++ b/jackson-modules/jackson-exceptions/src/main/java/com/baeldung/exceptions/PersonContact.java @@ -0,0 +1,33 @@ +package com.baeldung.exceptions; + +public class PersonContact { + + private String firstName; + private String lastName; + private Contact contact; + + public String getFirstName() { + return firstName; + } + + public void setFirstName(String firstName) { + this.firstName = firstName; + } + + public String getLastName() { + return lastName; + } + + public void setLastName(String lastName) { + this.lastName = lastName; + } + + public Contact getContact() { + return contact; + } + + public void setContact(Contact contact) { + this.contact = contact; + } + +} diff --git a/jackson-modules/jackson-exceptions/src/test/java/com/baeldung/exceptions/JacksonExceptionsUnitTest.java b/jackson-modules/jackson-exceptions/src/test/java/com/baeldung/exceptions/JacksonExceptionsUnitTest.java index 38ef3f9390..127d466436 100644 --- a/jackson-modules/jackson-exceptions/src/test/java/com/baeldung/exceptions/JacksonExceptionsUnitTest.java +++ b/jackson-modules/jackson-exceptions/src/test/java/com/baeldung/exceptions/JacksonExceptionsUnitTest.java @@ -3,17 +3,14 @@ package com.baeldung.exceptions; import static org.hamcrest.Matchers.containsString; import static org.junit.Assert.assertEquals; import static org.junit.Assert.assertThat; +import static org.junit.Assert.assertThrows; +import static org.junit.Assert.assertTrue; import java.io.IOException; import java.util.List; import org.junit.Test; -import com.baeldung.exceptions.User; -import com.baeldung.exceptions.UserWithPrivateFields; -import com.baeldung.exceptions.UserWithRoot; -import com.baeldung.exceptions.Zoo; -import com.baeldung.exceptions.ZooConfigured; import com.fasterxml.jackson.annotation.JsonAutoDetect.Visibility; import com.fasterxml.jackson.annotation.PropertyAccessor; import com.fasterxml.jackson.core.JsonFactory; @@ -82,6 +79,32 @@ public class JacksonExceptionsUnitTest { .readValue(json); } + @Test + public void givenJsonObject_whenDeserializingIntoString_thenException() throws IOException { + final String json = "{\"firstName\":\"Azhrioun\",\"lastName\":\"Abderrahim\",\"contact\":{\"email\":\"azh@email.com\"}}"; + final ObjectMapper mapper = new ObjectMapper(); + + Exception exception = assertThrows(JsonMappingException.class, () -> mapper.reader() + .forType(Person.class) + .readValue(json)); + + assertTrue(exception.getMessage() + .contains("Cannot deserialize value of type `java.lang.String` from Object value (token `JsonToken.START_OBJECT`)")); + } + + @Test + public void givenJsonObject_whenDeserializingIntoObject_thenDeserialize() throws IOException { + final String json = "{\"firstName\":\"Azhrioun\",\"lastName\":\"Abderrahim\",\"contact\":{\"email\":\"azh@email.com\"}}"; + final ObjectMapper mapper = new ObjectMapper(); + + PersonContact person = mapper.reader() + .forType(PersonContact.class) + .readValue(json); + + assertEquals("azh@email.com", person.getContact() + .getEmail()); + } + @Test public void givenDefaultConstructor_whenDeserializing_thenCorrect() throws IOException { final String json = "{\"id\":1,\"name\":\"John\"}";