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https://issues.apache.org/jira/browse/ARROW-17430?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17580463#comment-17580463
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David Li commented on ARROW-17430:
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We would definitely welcome a PR with List/MapBinder implementations!
Otherwise, I don't think I'd have the time to get to this for a while.
> [Java] ListBinder to bind Arrow List type to DB column
> -------------------------------------------------------
>
> Key: ARROW-17430
> URL: https://issues.apache.org/jira/browse/ARROW-17430
> Project: Apache Arrow
> Issue Type: Improvement
> Components: Java
> Affects Versions: 10.0.0
> Reporter: Igor Suhorukov
> Priority: Major
>
> Typical real life Arrow datasets contain List type vectors of primitive type.
> Looks logically implement default JDBC parameter binders for such vector type
> or implement some kind on binder code extensibility of core framework via
> MetaINF/ServiceLocator
> Current implementation just [throws UnsupportedOperationException|#L80]]
>
> {code:java}
> @Override
>
>
> public ColumnBinder visit(ArrowType.List type) {
>
>
> throw new UnsupportedOperationException("No column binder
> implemented for type " + type);
>
>
> } {code}
>
> My current implementation patch {color:#000000}ColumnBinderArrowTypeVisitor
> in classpath (to leverage Builder functionality instead of manual vector
> mapping in code) to return ListBinder{color}
> {code:java}
> @Override
> public ColumnBinder visit(ArrowType.List type) {
> return new ListBinder((ListVector) vector);
> } {code}
> {color:#000000}and following code works for me with H2 database and in java
> stored PostgreSQL {color}{color:#000000}function in PL/Java to bind List
> parameter to JDBC:{color}
> {code:java}
> package org.apache.arrow.adapter.jdbc.binder;
> import org.apache.arrow.vector.complex.ListVector;
> import org.apache.arrow.vector.complex.impl.UnionListReader;
> import java.sql.PreparedStatement;
> import java.sql.SQLException;
> import java.sql.Types;
> import java.util.ArrayList;
> import java.util.Arrays;
> public class ListBinder extends BaseColumnBinder<ListVector>{
> private UnionListReader reader;
> public ListBinder(ListVector vector) {
> this(vector, Types.ARRAY);
> }
> public ListBinder(ListVector vector, int jdbcType) {
> super(vector, jdbcType);
> reader = vector.getReader();
> }
> @Override
> public void bind(PreparedStatement statement, int parameterIndex, int
> rowIndex) throws SQLException {
> reader.setPosition(rowIndex);
> ArrayList sourceArray = (ArrayList) reader.readObject();
> Class aClass = sourceArray.get(0).getClass();
> if(aClass.isAssignableFrom(Long.class)){
> Long[] res = new Long[sourceArray.size()];
> Arrays.setAll(res, sourceArray::get);
> statement.setObject(parameterIndex, res);
> } else
> if(aClass.isAssignableFrom(Integer.class)){
> Integer[] res = new Integer[sourceArray.size()];
> Arrays.setAll(res, sourceArray::get);
> statement.setObject(parameterIndex, res);
> } else
> if(aClass.isAssignableFrom(Short.class)){
> Short[] res = new Short[sourceArray.size()];
> Arrays.setAll(res, sourceArray::get);
> statement.setObject(parameterIndex, res);
> } else
> if(aClass.isAssignableFrom(String.class)){
> String[] res = new String[sourceArray.size()];
> Arrays.setAll(res, sourceArray::get);
> statement.setObject(parameterIndex, res);
> }
> }
> }
> {code}
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