Skip Import Row with Invalid Value for Field Type in Magento 1.9

The mapper only works with exporting data. The documentation didn't mention that :(

I will map the fields myself in the saveRow method of my adapter. Following code works fine:

<action type="dataflow/convert_adapter_io" method="load">
    <var name="type">file</var>
    <var name="path">var/import</var>
    <var name="filename"><![CDATA[stuff.csv]]></var>
    <var name="format"><![CDATA[csv]]></var>
</action>

<action type="dataflow/convert_parser_csv" method="parse">
    <var name="delimiter"><![CDATA[,]]></var>
    <var name="enclose"><![CDATA["]]></var>
    <var name="fieldnames">false</var>
    <var name="number_of_records">10</var>
    <var name="adapter">mymodule/convert_adapter_myadapter</var>
    <var name="method">saveRow</var>
</action>

The simplest way is probably to use Magmi:

http://sourceforge.net/apps/mediawiki/magmi/index.php?title=Main_Page

This will let you update only the attributes you need to, and you can skip the ones you don't want to update or enter. So for example, if you are updating existing product, you need to only enter SKU and then at least 1 other attribute that you want updated. I think this is what you need if I understand your question correctly. If this isn't your answer, please re-word your question detailing the problem specifically.