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From paulomourajr <paulo.lis...@paulomourajr.net>
Subject Re: "can't infer the SQL type" of a bean property whose type is a generic parameter.
Date Sun, 20 Jan 2008 11:58:39 GMT

Hi, Grinshpun,

I faced this same problem a couple of hours ago. In my case, I have a
generic class like this (names were changed for the sake of

public class GenericModel<PK extends Serializable> {

     protected PK id;

    public PK getId(){
       return id;

    public void setId(PK value){
         this.id = value;

and one class like this:

public UF extends GenericModel<Long> {

    private String name;

    //getters and setters

The original result map and update statement generated using abator were
like this:

  <resultMap class="UF" id="UFResult">
    <result column="COD_UF" jdbcType="BIGINT" property="id"/>
    <result column="NAM_UF" jdbcType="VARCHAR" property="name"/>

  <update id="updateByPrimaryKey" parameterClass="UF">
    update uf
    set NAM_UF = #name:VARCHAR#
    where COD_UF = #id:BIGINT#

When I tried to use them, I got the same problem you reported. One solution
I found was to specify the java type in each statement using this property.
Changed result map and update statement are here:

  <resultMap class="UF" id="UFResult">
    <result column="COD_UF" jdbcType="BIGINT" property="id"
    <result column="NAM_UF" jdbcType="VARCHAR" property="name"/>

  <update id="updateByPrimaryKey" parameterClass="UF">
    update uf
    set NAM_UF = #name:VARCHAR#
    where COD_UF = #id,javaType=long,jdbcType

After this, everything went fine. But I found this solution a little
cumbersome, since it is not a special type which requires a special type
handler. Anybody has another alternative to this?


Vadim Grinshpun wrote:
> Hi all,
> I just ran into an interesting problem, and I'm curious whether I'm 
> doing something wrong, or if it's a known limitation or bug in iBATIS 
> (or its interaction with the JDBC driver?). I'm using iBATIS 2.3.0 with 
> a PostgreSQL's jdbc driver 8.2-504.
> Let's say I have the following classes:
> // wrapper that attaches an attribute to things; a poor-man's mix-in class
> class Wrapper<T>{
>     String wrapperAttribute;
>     T value;
>     String getAttribute() { return wrapperAttribute;}
>     T getValue() { return value; };
>      // remaining bean accessors are defined but not shown
>      // ...
> }
> // a class that uses the  wrapper:
> class FooBean{
>    Wrapper<String> wrappedString;
>    Wrapper<Date> wrappedDate;
>    Wrapper<SomeEnum> wrappedEnum; // Enum and its TypeHandlerCallback 
> are defined elsewhere, not shown
>    // the obvious get/set accessors are defined below, not shown
>    // ...
> }
> // end code
> FooBean is then passed as a parameter to an insert statement, which 
> looks, roughly, along the lines of:
>  <insert ... >
>       INSERT INTO mytable ( string_field, date_field, enum_field )
>       VALUES( #wrappedString.value#,
>                       #wrappedDate.value#,
>                       #wrappedEnum.value# )
>  </insert>
> When trying to run the code, the #wrappedString.value# part of the 
> statement works just fine, but for the #wrappedDate.value# I  get an
> error:
>     "PSQLException: Can't infer the SQL type to use for an instance of 
> java.util.Date. Use setObject() with an explicitly Types value to 
> specify the type to use."
> Seeing this, I tried adding the jdbc type to the parameter map, as shown:
>                       #wrappedDate.value:TIMESTAMP#
> This produced the same exact error.
> Then I tried adding a wrapper method,"Date getWrappedDateValue" which 
> simply calls getWrappedDate().getValue(), and thus returns a Date 
> object, but then I got the same error for the wrappedEnum...
> Can anyone explain this? Is there a way to get this to work properly? I 
> first thought that this has to do with Java's generic not preserving 
> enough information for this to work, but as the error message clearly 
> shows, the type info is retrievable...
> Thanks for any insight!
> -Vadim

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