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From Travis <travi...@travnet.org>
Subject iBatis 3 Java, an annotation for select, with result map in XML
Date Tue, 20 Apr 2010 15:38:50 GMT
Hi there,

I recently have been upgrading my iBatis 2.x projects to now use iBatis 
3.  I really appreciate the work done to create this new Mapper 
interface. And related I have started to play with having some of the 
simpler queries live as @Select annotations on the mapper interface 
method now instead of in the XML.

I noticed for the @Select annotation, it is possible to have the results 
of the statement mapped to a java bean if I use the @Results annotation.

Would it be possible to create a new annotation (or does one exist 
already and I just have not found it yet),  where I can specify that 
@Select results should be a <resultMap>  that exists in the mapper XML 
file ?

For example,

Consider a "country" table,

    CODE varchar(2) NOT NULL,
    ISO_CODE varchar(3) NOT NULL,
    NAME varchar(2147483647),
    COUNTRY_CODE varchar(10),

And the java Bean,

public class Country {
   Long    id;
   String  code;         // 2 digit ISO country code
   String  isoCode;      // 3 digit ISO country code
   String  name;         // string name
   String  countryCode;  // the telephone dialing prefix (e.g. +1)
   boolean active = true;

   // and all the get()  set() methods for these bean properties

And then the mapper interface,

public interface CountryDAO {

   * Selects all country entries.
   * Though it appears when we use the annotations, we need to specify 
the results every time ?
   @Select( value = { "select * from country where active = true" })
   @Results(value = {
       @Result(property="isoCode", column="iso_code"),
       @Result(property="name", column="name"),
       @Result(property="countryCode", column="country_code"),
       @Result(property="active", column="active")
   List<Country> getAllActive();

   // TODO: all these methods would also be select queries, where I 
would want the same results map as above
   Country getById(Long id);
   Country getByCode(String code);
   Country getByIsoCode(String isoCode);

Where, instead of the @Results  annotation, which would need to be 
duplicated with its nested @Result annotations on every select method 
that I want to return the same mapping, what I would wish to have would 
be something like a


annotation, where the myMapperID would be the ID of a <resultMap> I have 
declared in the mapper's xml file that will be included by the 
SqlMapConfig.xml (which I have anyway to bind to this mapper interface, 
and also because I have some more complex queries declared in the xml 
mapper file too).

Where in this example, I already have a

<mapper namespace="CountryDAO">

<resultMap type="Country" id="countryResult">
<result property="id" column="id"/>
<result property="code" column="code"/>
<result property="isoCode" column="iso_code"/>
<result property="name" column="name"/>
<result property="countryCode" column="country_code"/>
<result property="active" column="active"/>

So this wishful @ResultMap annotation would then make the mapper 
interface look like:

public interface CountryDAO {

   @Select( value = { "select * from country where active = true" })
   @ResultMap(value = "countryResult")
   List<Country> getAllActive();

   // and now other things that want to select into this map can do so, 
re-using the single map declaration
   // that is referenced in the xml.

   @Select( value = { "select * from country where id = #{id} })
   @ResultMap(value = "countryResult")
   Country getById(Long id);

   @Select( value = { "select * from country where code = #{code} })
   @ResultMap(value = "countryResult")
   Country getByCode(String code);

   @Select( value = { "select * from country where isoCode = #{isoCode} })
   @ResultMap(value = "countryResult")
   Country getByIsoCode(String isoCode);

I think having something like this @ResultMap annotation would be a good 
thing to have,  what do you think?


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