Hi all,
I have a tool where for one parameter I want the user to pick one or more columns from a tabular file. Other tools do this too, e.g. filters/uniq.xml (the Statistics "Count" tool) uses:
<inputs> <param name="input" type="data" format="tabular" label="from query" help="Query missing? See TIP below"/> <param name="column" type="data_column" data_ref="input" multiple="True" numerical="False" label="Count occurrences of values in column(s)" help="Multi-select list - hold the appropriate key while clicking to select multiple columns" /> ... </inputs>
I would like extend this by adding a validator to prevent the user trying to run my tool with no columns (in fact, I think this would be a good idea for filters/uniq.xml as well - currently the error is only spotted when the tool is run).
There is a list of validators given on the wiki page, http://bitbucket.org/galaxy/galaxy-central/wiki/ToolConfigSyntax
I expected to be able to use the empty_field validator, but that doesn't work - is this a bug?:
<param name="column" type="data_column" data_ref="input" multiple="True" numerical="False" label="Count occurrences of values in column(s)" help="Multi-select list - hold the appropriate key while clicking to select multiple columns"> <validator type="empty_field" message="Pick at least one column"/> </param>
I found a workaround, based on the fact that no columns is passed to the command line tools as the string 'None', using the expression validator:
<param name="column" type="data_column" data_ref="input" multiple="True" numerical="False" label="Count occurrences of values in column(s)" help="Multi-select list - hold the appropriate key while clicking to select multiple columns"> <validator type="expression" message="Pick at least one column">str(value)!='None'</validator> </param>
Peter