How do I pre-select rows in a DataTable based on the value in a column? - pandas

Question

Situation:
I have a pandas dataframe which I convert into an html table via df.to_html(). I then add the DataTables class to the table. This DataTables-table has the following columns:
ID | X | Y | Val |...More columns...| Selection_Criteria |...More columns...
The values in Selection_Criteria can be either 1 or 0. I know that with:
$('#ProductList').DataTable( {
...
"fnInitComplete": function(oSettings, json) { $('#ProductList tbody tr:eq(0)').click(); }
});
(Source: http://code.datatables.net/forums/discussion/38171/automatic-select-of-the-first-row-on-reload)
..it is theoretically possible to select the first row. (In reality, I have not been able to simulate a click for the first row.)
But my question goes more towards: How do I automatically pre-select ALL rows where the value is 1 in Selection_Criteria? What is the best approach? Should this be done client/server side?

Answer 1

In pandas the term "select"(ing) means to screen out that which was not selected for. I know that in a table on a web page, selected can mean being highlighted to stand out from the others. There are a couple of ways you can do this on the server side. You could display two tables, one for each state of Selection_Criteria. This would save you the hassle of trying to select individual rows out of a table in the first place (which would be done with Javascript, not Pandas). While pandas has the ability to add a class to the resulting html, the class is applied to the element.
If you are using jquery you are going to use these pieces. as you haven't put example data I can't be exact.
replace x in the next line with the number of columns the Selection_Criteria=1 is across the table
$( "tr td:nth-child(x):contains('1')" ).addClass('selected');
There are solutions on the backend using beautifulsoup and css selectors, or lxml.etree with xpath selectors. But jquery is going to be the most concise with this problem.

Answer 2

#Aliester. Thank you for the pointer!
This helped me find the solution to my own question. What I did:
1.) Identify row index that I want to select when the table loads.
2.) Pass the index to js.
3.) Loop over the indices and apply the following command to each index entry:
table.row(':eq('+hit_index_row+')').select();
So I am using the API to select each individual row. This works for me and hopefully could be helpful to others as well. It may be a bit hacky, so more elegant suggestions are welcome!

Answer 3

You can do this by providing a function for the "rowCallback" option when initializing the DataTable. https://datatables.net/reference/option/rowCallback
Also it is generally better to use the API methods to select rows instead of just changing the class. I found that the DataTable + Select libraries keep an internal collection of selected row indexes (just current page if serverside processing is on) instead of using the class to resolve selected items.
So while the display will look right, if you just change the class, if you rely on any of the API methods to get selected items later on there will be issues. Additionally just changing the class on the row will not fire any of the "select" events on the table so you can't rely on those either.