SpringBoot中測試Elasticsearch，在測試ElasticsearchRepository文檔操作中的查詢時報錯org.springframework.data.elasticsearch.ElasticsearchException: failed to map source *** to class item

問題描述：

在SpringBoot中測試Elasticsearch的時候，當測試ElasticsearchRepository的文檔操作的時候，在調用find()查詢方法時報錯，錯誤如下：

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `com.zmx.elasticsearch.pojo.Item` (no Creators, like default construct, exist): 
cannot deserialize from Object value (no delegate- or property-based Creator)
at [Source: (String); line: 1, column: 2]
at com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:67)
at com.fasterxml.jackson.databind.DeserializationContext.reportBadDefinition(DeserializationContext.java:1452)
at com.fasterxml.jackson.databind.DeserializationContext.handleMissingInstantiator(DeserializationContext.java:1028)
at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromObjectUsingNonDefault(BeanDeserializerBase.java:1297)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:326)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:159)
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4013)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3004)
at org.springframework.data.elasticsearch.core.DefaultEntityMapper.mapToObject(DefaultEntityMapper.java:82)
at org.springframework.data.elasticsearch.core.AbstractResultMapper.mapEntity(AbstractResultMapper.java:43)
... 56 more

 

原因：

這是因為在實體類Item中為了方便實例化添加了一個有參構造函數，導致JVM不能添加默認的無參構造函數了，但是jackson的反序列化需要使用無參構造函數，所以報錯！

解決：

在實體類Item中添加一個無參構造函數就可以了！

引用：

https://www.cnblogs.com/yucfeng/p/8932089.html#4131391 更加詳細的介紹可以參考這個朋友的文章！