Kotlin – 杰克逊忽略空值

我解析与杰克逊JSON的麻烦，我想忽略空属性。 这是我的代码。

@JsonIgnoreProperties(ignoreUnknown = true) @JsonInclude(JsonInclude.Include.NON_NULL) data class ParsedSurvey( val items: List<ParsedSurveyItem> = listOf() ) @JsonIgnoreProperties(ignoreUnknown = true) @JsonInclude(JsonInclude.Include.NON_NULL) data class ParsedSurveyItem( val type: String = "", val text: String = "", val instructions: String = "", val prog: String = "", val `var`: String = "", val columns: List<ParsedSurveyAnswer> = listOf(), val rows: List<ParsedSurveyAnswer> = listOf(), val num: String = "", val multi: Boolean = false, val random: Boolean = false, val min: Int = -1, val max: Int = -1, val recordOrder: Boolean = false, val rowLength: Int = -1 ) @JsonIgnoreProperties(ignoreUnknown = true) @JsonInclude(JsonInclude.Include.NON_NULL) data class ParsedSurveyAnswer @JsonCreator(mode = JsonCreator.Mode.PROPERTIES) constructor( val text: String = "", val prog: String = "<p></p>", @JsonProperty("isOpen") val isOpen: Boolean = false ) 

如果我尝试将ParsedSurveyItem中的行属性设置为null。 我得到这个错误：

 value failed for JSON property rows due to missing (therefore NULL) value for creator parameter rows which is a non-nullable type. Jackson doesn't ignore 

为什么杰克逊分析空值？ 感谢帮助。

Answer 1

只有在可为null才能将行属性设置为null 。 这意味着改变它

  val rows: List<ParsedSurveyAnswer>? 

你也可以删除listOf() ＆ @JsonIgnoreProperties(ignoreUnknown = true)