java - Lombok + Jackson => MismatchedInputException

Question

我有一个 PSQL 表，其中一列包含 jsonb 数据:

CREATE TABLE IF NOT EXISTS user (
    user_name VARCHAR(255) NOT NULL,
    user_email VARCHAR(255) NOT NULL,
    user_address jsonb NOT NULL
)

我有以下java对象:

import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
import com.fasterxml.jackson.databind.annotation.JsonPOJOBuilder;
import lombok.Builder;
import lombok.Value;

@Value
@Builder
public class User {
    private String userName;
    private String userEmail;
    private UserAddress address;

    @Value
    @Builder
    @JsonDeserialize(builder = UserAddress.UserAddressBuilder.class)
    public static class UserAddress {
        @JsonProperty("street")
        private String street;
        @JsonProperty("house_number")
        private String houseNumber;

        @JsonPOJOBuilder(withPrefix = "")
        public static class UserAddressBuilder {
            private String street = null;
            private String houseNumber = null;

            public UserAddressBuilder street(String street) {
               this.street = street;

               return this;
            }

            public UserAddressBuilder houseNumber(String houseNumber) {
                this.houseNumber = houseNumber;

                return this;
            }
        }
    }
}

当我现在从 ResultSet 构建 User 时:

return User.builder()
        .userName(rs.getString(SqlConstants.TableUser.USER_NAME))
        .userEmail(rs.getString(SqlConstants.TableUser.USER_EMAIL))
        .userAddress(mapper.convertValue(rs.getString(SqlConstants.TableUser.USER_ADDRESS), User.UserAddress.class))
        .build();

我总是遇到异常:

Caused by: com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of my.package.model.User$UserAddress$UserAddressBuilder (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('"{\"street\":\"Some Street\",\"house_number\":\"Some House Number\"}')

我找不到这个问题的根源，因为字段是匹配的，不是吗？ 我还尝试了没有 @Builder 的方法，并使用 @Data、@AllArgsConstructor 和 @NoArgsConstructor 代替。 p>

使用 readValue 而不是 convertValue 时得到相同的结果

Answer 1

正如评论中提到的使用

.userAddress(mapper.readValue(rs.getString(SqlConstants.TableUser.USER_ADDRESS), 
                                              User.UserAddress.class))

应该工作得很好，至少对我来说是这样。但是，在进行更改之后，您可能会遇到:

com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "house_number" ...

(而不是原来的错误)，这将通过对您的 UserAddressBuilder 进行小的更改来修复:

@JsonProperty("house_number") // this is also needed to map correctly
public UserAddressBuilder houseNumber(String houseNumber) { ...

来自Javadoc :

public T convertValue(Object fromValue, Class toValueType)
throws IllegalArgumentException

Convenience method for doing two-step conversion from given value, into instance of given value type. This is functionality equivalent to first serializing given value into JSON, then binding JSON data into value of given type, but may be executed without fully serializing into JSON. Same converters (serializers, deserializers) will be used as for data binding, meaning same object mapper configuration works

而readValue用于从字符串、流、读取器读取对​​象值。使用 convertValue(..) 您可能需要定义转换器，但在您的情况下不需要。