mybatis 3.4.4 use annotation @Result can not map custom Java generic that already define the class Type in return param

[喻奇]

just like pic show

，I have difine RecordInfo<T>  class , and i Return the RecordInfo<RiskInfo>  in queryRiskList function.but i use @Result(property = "content.appId", column = "app_id")  to map RiskInfo class Feild appId to database column app_id when I run  this function,I get this error "org.apache.ibatis.reflection.ReflectionException: There is no setter for property named 'appId' in 'class java.lang.Object'",  but I define the  type of content as RiskInfo in Function return params, why mybatis can not

 discern the RiskInfo class，how could I solve this error？

[Guy Rouillier]

Why is your map mapping appId twice, once for appInfo.appId and again for content.appId?

To answer your question, this appears to be the classic problem of type erasure with generics:

https://www.baeldung.com/java-type-erasure

--

Guy Rouillier

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[喻奇]

在 2020年3月17日星期二 UTC+8下午4:42:54，Guy Rouillier写道：

Why is your map mapping appId twice, once for appInfo.appId and again for content.appId?

To answer your question, this appears to be the classic problem of type erasure with generics:

https://www.baeldung.com/java-type-erasure

--

Guy Rouillier

On 3/17/2020 12:47:11 AM, "喻奇" <yich...@gmail.com> wrote:

just like pic show

，I have difine RecordInfo<T>  class , and i Return the RecordInfo<RiskInfo>  in queryRiskList function.but i use @Result(property = "content.appId", column = "app_id")  to map RiskInfo class Feild appId to database column app_id when I run  this function,I get this error "org.apache.ibatis.reflection.ReflectionException: There is no setter for property named 'appId' in 'class java.lang.Object'",  but I define the  type of content as RiskInfo in Function return params, why mybatis can not

 discern the RiskInfo class，how could I solve this error？

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hi，thanks for your reply，mapping appId twice is not question that i ask,my question neither is java Type Erasure ，i wonder  “use annotation @Result can not map custom Java generic that already define the class Type in return param”

[Guy Rouillier]

>> my question neither is java Type Erasure ，i wonder  “use annotation @Result can not map custom Java generic that already define the class Type in return param”

Well, that may not be the question you asked, but appears to be the situation you face:

"org.apache.ibatis.reflection.ReflectionException: There is no setter for property named 'appId' in 'class java.lang.Object'"

If you are able to post a *simple* example, I'm willing to take a look, since we are on coronavirus isolation.  From what you have provided, I cannot see how "content" is defined.

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Guy Rouillier

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[喻奇]

as the pic show，content is defined as  Java generic, but at the function return param "RecordInfo<RiskInfo>" ,I already define java generic T as  "RiskInfo.class",  so why "use annotation @Result can not map custom Java generic that already define the class Type in return param" 

在 2020年3月20日星期五 UTC+8下午1:11:51，Guy Rouillier写道：

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