Using the following code of multi-filtering select
inputs in Datatables
is it possible to show only available values in the other select inputs upon a selection in one filter? To be more precise, in this example if I select 'Tokyo' as an Office, I would like to populate only the values 'Accountant', 'Integration Specialist', 'Support Engineer' and 'Regional Marketing' in the dropdown menu of Position.
$(document).ready(function() {
$('#example').DataTable( {
initComplete: function () {
this.api().columns([1,2]).every( function () {
var column = this;
var select = $('<select><option value=""></option></select>')
.appendTo( $(column.footer()).empty() )
.on( 'change', function () {
var val = $.fn.dataTable.util.escapeRegex(
$(this).val()
);
column
.search( val ? '^'+val+'$' : '', true, false )
.draw();
} );
column.data().unique().sort().each( function ( d, j ) {
select.append( '<option value="'+d+'">'+d+'</option>' )
} );
} );
}
} );
} );
////// here I get the unique values of each filtered `select` option
$('select').on('change', function () {
var dtable = $('#datatable').DataTable();
var filteredArray = [];
var filteredArray2 = [];
dtable.column(1, { search: 'applied' }).data()
.unique()
.sort()
.each(function (value, index) {
filteredArray.push(value);
});
dtable.column(2, { search: 'applied' })
.data()
.unique()
.sort()
.each(function (value, index) {
filteredArray2.push(value);
});
console.log(filteredArray);
console.log(filteredArray2);
});
In my case I have filters in two columns only as it is shown in the above snippet, so upon selection in one of the two filters I would ideally like to show only available values in the other filter.
Although I have managed to get the unique values of each filter upon a selection I am struggling to hide all the input
values that do not exist in the filteredArrays
Here is one approach for doing this.
The end result is as follows:
Building a drop-down which only contains the unfiltered (visible) values of a column is relatively straightforward. At the heart of doing this we use the following:
columns( { search: 'applied' } ).data()[index]
Most of the complexity relates to managing the inter-related states of the two drop-downs. After loading the page, whichever drop-down gets used first is designated as the "primary" drop-down and the other is the "secondary". Whenever the user selects a new value from the primary drop-down, we have to clear the secondary drop-down; and then after the primary drop-down filter has been applied, we have to re-build the secondary drop-down's list of values.
The end result is this:
<script type="text/javascript">
/* Each drop-down selection affects the values in the other drop-downs */
var primaryColIdx;
var secondaryColIdx;
$(document).ready(function() {
$('#example').DataTable( {
initComplete: function () {
populateDropdowns(this);
}
} );
} );
function populateDropdowns(table) {
table.api().columns([1,2]).every( function () {
var column = this;
//console.log("processing col idx " + column.index());
var select = $('<select><option value=""></option></select>')
.appendTo( $(column.footer()).empty() )
.on( 'change', function () {
var dropdown = this;
doFilter(table, dropdown, column);
rebuildSecondaryDropdown(table, column.index());
} );
column.data().unique().sort().each( function ( val, idx ) {
select.append( '<option value="' + val + '">' + val + '</option>' )
} );
} );
}
function doFilter(table, dropdown, column) {
// first time a drop-down is used, it becomes the primary. This
// remains the case until the page is refreshed:
if (primaryColIdx == null) {
primaryColIdx = column.index();
secondaryColIdx = (primaryColIdx == 1) ? 2 : 1;
}
if (column.index() === primaryColIdx) {
// reset all the filters because the primary is changing:
table.api().search( '' ).columns().search( '' );
}
var filterVal = $.fn.dataTable.util.escapeRegex($(dropdown).val());
//console.log("firing dropdown for col idx " + column.index() + " with value " + filterVal);
column
.search( filterVal ? '^' + filterVal + '$' : '', true, false )
.draw();
}
function rebuildSecondaryDropdown(table, primaryColIdx) {
var secondaryCol;
table.api().columns(secondaryColIdx).every( function () {
secondaryCol = this;
} );
// get only the unfiltered (unhidden) values for the "other" column:
var raw = table.api().columns( { search: 'applied' } ).data()[secondaryColIdx];
// the following uses "spread syntax" (...) for sorting and de-duping:
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_syntax
var uniques = [...new Set(raw)].sort();
var filteredSelect = $('<select><option value=""></option></select>')
.appendTo( $(secondaryCol.footer()).empty() )
.on( 'change', function () {
var dropdown = this;
doFilter(table, dropdown, secondaryCol);
//rebuildSecondaryDropdown(table, column.index());
} );
uniques.forEach(function (item, index) {
filteredSelect.append( '<option value="' + item + '">' + item + '</option>' )
} );
}
</script>