Fix: If a column data type is null when it is sorted, it should be re…

…solved. This could happen after data has been invalidated (e.g. after column reordering).

DataTables/ColReorder#90

js/core/core.sort.js

@@ -220,10 +220,14 @@ function _fnSort ( oSettings, col, dir )
 		displayMaster = oSettings.aiDisplayMaster,
 		aSort;
 
+	// Make sure the columns all have types defined
+	_fnColumnTypes(oSettings);
+
 	// Allow a specific column to be sorted, which will _not_ alter the display
 	// master
 	if (col !== undefined) {
 		var srcCol = oSettings.aoColumns[col];
+
 		aSort = [{
 			src:       col,
 			col:       col,

test/functional/features/data-type.js

@@ -2,14 +2,16 @@ describe('Data type detection', function () {
 	var table;
 	var data = [];
 
-	for ( var i=0 ; i<100 ; i++) {
-		data.push([
-			'a',                     // plain string
-			i,                       // number
-			'<div>' + i + '</div>',  // HTML number
-			'2020-01-01',            // Date
-			'c' + i,                 // String
-			'<div>d' + i + '</div>'] // HTML
+	for (var i = 0; i < 100; i++) {
+		data.push(
+			[
+				'a', // plain string
+				i, // number
+				'<div>' + i + '</div>', // HTML number
+				'2020-01-01', // Date
+				'c' + i, // String
+				'<div>d' + i + '</div>'
+			] // HTML
 		);
 	}
 
@@ -23,14 +25,14 @@ describe('Data type detection', function () {
 	it('Types detected as expected', function () {
 		table = new DataTable('#example', {
 			data: data
-		  });
-
-		  expect(table.column(0).type()).toBe('string');
-		  expect(table.column(1).type()).toBe('num');
-		  expect(table.column(2).type()).toBe('html-num');
-		  expect(table.column(3).type()).toBe('date');
-		  expect(table.column(4).type()).toBe('string');
-		  expect(table.column(5).type()).toBe('html');
+		});
+
+		expect(table.column(0).type()).toBe('string');
+		expect(table.column(1).type()).toBe('num');
+		expect(table.column(2).type()).toBe('html-num');
+		expect(table.column(3).type()).toBe('date');
+		expect(table.column(4).type()).toBe('string');
+		expect(table.column(5).type()).toBe('html');
 	});
 
 	dt.html('empty');
@@ -40,13 +42,39 @@ describe('Data type detection', function () {
 			data: data,
 			searching: false,
 			ordering: false
-		  });
-
-		  expect(table.column(0).type()).toBe('string');
-		  expect(table.column(1).type()).toBe('num');
-		  expect(table.column(2).type()).toBe('html-num');
-		  expect(table.column(3).type()).toBe('date');
-		  expect(table.column(4).type()).toBe('string');
-		  expect(table.column(5).type()).toBe('html');
+		});
+
+		expect(table.column(0).type()).toBe('string');
+		expect(table.column(1).type()).toBe('num');
+		expect(table.column(2).type()).toBe('html-num');
+		expect(table.column(3).type()).toBe('date');
+		expect(table.column(4).type()).toBe('string');
+		expect(table.column(5).type()).toBe('html');
+	});
+
+	// Data types after an invalidation
+	// https://github.com/DataTables/ColReorder/issues/90
+	dt.html('empty');
+
+	it('Type detected as expected on start up', function () {
+		table = new DataTable('#example', {
+			data: data
+		});
+
+		expect(table.column(3).type()).toBe('date');
+	});
+
+	it('Invalidate data causes type to be null', function () {
+		table.cell(0, 3).invalidate('data');
+
+		// Note need, to check the internal value, as `column().type()` will resolve the
+		// type
+		expect(table.settings()[0].aoColumns[3].sType).toBe(null);
+	});
+
+	it('Ordering by the column resolves type', async function () {
+		await dt.clickHeader(3);
+
+		expect(table.settings()[0].aoColumns[3].sType).toBe('date');
 	});
 });