copy doesn't support the nested "if" element in Ant-contrib Nested Loop - ant

Question

I need to copy all dml.sql files to inside DB2_List.txt file if DML.sql file is present. But after executing this file i'm getting error like this:
copy doesn't support the nested "if" element.
Please let me know if you have any better idea about the nested loop in Ant.
<available file="DB/DML.sql" property="db.check.present"/>
<copy file="DB/DDL.sql" tofile="DB2/DB2_List.txt" >
<if>
<equals arg1="${db.check.present}" arg2="true"/>
<then>
<filterchain>
<concatfilter append="DB/DML.sql" />
<tokenfilter delimoutput="${line.separator}" />
</filterchain>
</then>
</if>
</copy>

Answer 1

It is possible to accomplish what you are after, you just have to approach it quite differently in Ant. Just note that you will need to utilize separate targets.
<target name="db.check">
<available file="DB/DML.sql" property="db.check.present"/>
</target>
<target name="db.copy" depends="db.check" if="db.check.present">
<copy file="DB/DDL.sql" tofile="DB2/DB2_List.txt" >
<filterchain>
<concatfilter append="DB/DML.sql" />
<tokenfilter delimoutput="${line.separator}" />
</filterchain>
</copy>
</target>

Answer 2

Take a look at Ant 1.9.1 which supports special if/unless attributes on tags. This might be possible:
<project name="mysterious.moe" basedir="." default="package"
xmlns:if="ant:if"
xmlns:unless="ant:unless"/>
<target name="db.copy">
<available file="DB/DML.sql" property="db.check.present"/>
<copy file="DB/DDL.sql"
tofile="DB2/DB2_List.txt">
<filterchain if:true="db.ceck.present">
<concatfilter append="DB/DML.sql" />
<tokenfilter delimoutput="${line.separator}" />
</filterchain>
</copy>
<target>
...
</project>
Otherwise, you'll have to use two separate copies. You can't put <if> antcontrib inside tasks. Only around tasks:
<available file="DB/DML.sql" property="db.check.present"/>
<if>
<equals arg1="${db.check.present}" arg2="true"/>
<then>
<copy file="DB/DDL.sql" tofile="DB2/DB2_List.txt" >
<filterchain>
<concatfilter append="DB/DML.sql" />
<tokenfilter delimoutput="${line.separator}" />
</filterchain>
</copy>
</then>
<else>
<copy file="DB/DDL.sql" tofile="DB2/DB2_List.txt" >
</else>
</if>
</copy>