Add 'filtering' for purchase order line item table

InvenTree/order/templates/order/purchase_order_detail.html

@@ -32,6 +32,9 @@
             </button>
             {% endif %}
             {% endif %}
+            <div class='filter-list' id='filter-list-purchase-order-lines'>
+                <!-- An empty div in which the filter list will be constructed-->
+            </div>
         </div>
         
         <table class='table table-striped table-condensed' id='po-line-table' data-toolbar='#order-toolbar-buttons'>

InvenTree/templates/js/translated/filters.js

@@ -273,6 +273,11 @@ function setupFilterList(tableKey, table, target) {
 
     var element = $(target);
 
+    if (!element) {
+        console.log(`WARNING: setupFilterList could not find target '${target}'`);
+        return;
+    }
+
     // One blank slate, please
     element.empty();
 

InvenTree/templates/js/translated/order.js

@@ -665,6 +665,18 @@ function loadPurchaseOrderTable(table, options) {
  */
 function loadPurchaseOrderLineItemTable(table, options={}) {
 
+    options.params = options.params || {};
+
+    var filters = loadTableFilters('purchaseorderlineitem');
+
+    for (var key in options.params) {
+        filters[key] = options.params[key];
+    }
+
+    var target = options.filter_target || '#filter-list-purchase-order-lines';
+
+    setupFilterList('purchaseorderlineitem', $(table), target);
+
     function setupCallbacks() {
         if (options.allow_edit) {
             $(table).find('.button-line-edit').click(function() {