Jackson deserialization error: MismatchedInputException

manpreet Best Answer 2 years ago

I have the following class

public class Cart {
    private final String id;

    public Cart(String id) { this.id = id;}

    public String getId() { return id; }
}

And the following test:

    String jsonString = "{\"id\":\"56c7b5f7-115b-4cb9-9658-acb7b849d5d5\"}";
    Cart cart = mapper.readValue(jsonString, Cart.class);
    assertThat(cart.getId()).isEqualTo("56c7b5f7-115b-4cb9-9658-acb7b849d5d5");

And I'm getting the following error:

com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance ofcom.store.domain.model.Cart (although at least one Creator exists): cannot deserialize from Object value (no delegate- or property-based Creator) at [Source: (String)"{"id":"56c7b5f7-115b-4cb9-9658-acb7b849d5d5"}"; line: 1, column: 2]

I can't figure out what's wrong here. Any help please?

manpreet 2 years ago

You need to define your bean as:

public class Cart {
    private final String id;

    @JsonCreator
    public Cart(@JsonProperty("id") String id) { this.id = id;}

    public String getId() { return id; }
}

public static void main(String[] args) throws IOException {
    ObjectMapper mapper = new ObjectMapper();
    String jsonString = "{\"id\":\"56c7b5f7-115b-4cb9-9658-acb7b849d5d5\"}";
    Cart cart = mapper.readValue(jsonString, Cart.class);
    System.out.println(mapper.writeValueAsString(cart));
}