如何创建自动完成的组合框？

Question

有谁知道用Knockout JS模板创建自动完成组合框的最佳方法吗？

我有以下模板：

<script type="text/html" id="row-template">
<tr>
...
    <td>         
        <select class="list" data-bind="options: SomeViewModelArray, 
                                        value: SelectedItem">
        </select>
    </td>
...        
<tr>
</script>

有时候，这个清单很长，我想让Knockout在jQuery自动完成功能或一些直接的JavaScript代码方面表现出色，但收效甚微。

另外，jQuery.Autocomplete需要输入字段。有任何想法吗？

Answer 1

这是我编写的jQuery
UI自动完成绑定。它的目的是镜像options，optionsText，optionsValue，value与几个新增的选择要素使用绑定模式（可以查询通过AJAX选项，你可以区分什么是显示在输入框中输入与所显示的选择框弹出起来。

您无需提供所有选项。它将为您选择默认值。

//jqAuto -- main binding (should contain additional options to pass to autocomplete)
//jqAutoSource -- the array to populate with choices (needs to be an observableArray)
//jqAutoQuery -- function to return choices (if you need to return via AJAX)
//jqAutoValue -- where to write the selected value
//jqAutoSourceLabel -- the property that should be displayed in the possible choices
//jqAutoSourceInputValue -- the property that should be displayed in the input box
//jqAutoSourceValue -- the property to use for the value
ko.bindingHandlers.jqAuto = {
    init: function(element, valueAccessor, allBindingsAccessor, viewModel) {
        var options = valueAccessor() || {},
            allBindings = allBindingsAccessor(),
            unwrap = ko.utils.unwrapObservable,
            modelValue = allBindings.jqAutoValue,
            source = allBindings.jqAutoSource,
            query = allBindings.jqAutoQuery,
            valueProp = allBindings.jqAutoSourceValue,
            inputValueProp = allBindings.jqAutoSourceInputValue || valueProp,
            labelProp = allBindings.jqAutoSourceLabel || inputValueProp;

        //function that is shared by both select and change event handlers
        function writeValueToModel(valueToWrite) {
            if (ko.isWriteableObservable(modelValue)) {
               modelValue(valueToWrite );  
            } else {  //write to non-observable
               if (allBindings['_ko_property_writers'] && allBindings['_ko_property_writers']['jqAutoValue'])
                        allBindings['_ko_property_writers']['jqAutoValue'](valueToWrite );    
            }
        }

        //on a selection write the proper value to the model
        options.select = function(event, ui) {
            writeValueToModel(ui.item ? ui.item.actualValue : null);
        };

        //on a change, make sure that it is a valid value or clear out the model value
        options.change = function(event, ui) {
            var currentValue = $(element).val();
            var matchingItem =  ko.utils.arrayFirst(unwrap(source), function(item) {
               return unwrap(item[inputValueProp]) === currentValue;  
            });

            if (!matchingItem) {
               writeValueToModel(null);
            }    
        }

        //hold the autocomplete current response
        var currentResponse = null;

        //handle the choices being updated in a DO, to decouple value updates from source (options) updates
        var mappedSource = ko.dependentObservable({
            read: function() {
                    mapped = ko.utils.arrayMap(unwrap(source), function(item) {
                        var result = {};
                        result.label = labelProp ? unwrap(item[labelProp]) : unwrap(item).toString();  //show in pop-up choices
                        result.value = inputValueProp ? unwrap(item[inputValueProp]) : unwrap(item).toString();  //show in input box
                        result.actualValue = valueProp ? unwrap(item[valueProp]) : item;  //store in model
                        return result;
                });
                return mapped;                
            },
            write: function(newValue) {
                source(newValue);  //update the source observableArray, so our mapped value (above) is correct
                if (currentResponse) {
                    currentResponse(mappedSource());
                }
            }
        });

        if (query) {
            options.source = function(request, response) {  
                currentResponse = response;
                query.call(this, request.term, mappedSource);
            }
        } else {
            //whenever the items that make up the source are updated, make sure that autocomplete knows it
            mappedSource.subscribe(function(newValue) {
               $(element).autocomplete("option", "source", newValue); 
            });

            options.source = mappedSource();
        }

        ko.utils.domNodeDisposal.addDisposeCallback(element, function () {
            $(element).autocomplete("destroy");
        });


        //initialize autocomplete
        $(element).autocomplete(options);
    },
    update: function(element, valueAccessor, allBindingsAccessor, viewModel) {
       //update value based on a model change
       var allBindings = allBindingsAccessor(),
           unwrap = ko.utils.unwrapObservable,
           modelValue = unwrap(allBindings.jqAutoValue) || '', 
           valueProp = allBindings.jqAutoSourceValue,
           inputValueProp = allBindings.jqAutoSourceInputValue || valueProp;

       //if we are writing a different property to the input than we are writing to the model, then locate the object
       if (valueProp && inputValueProp !== valueProp) {
           var source = unwrap(allBindings.jqAutoSource) || [];
           var modelValue = ko.utils.arrayFirst(source, function(item) {
                 return unwrap(item[valueProp]) === modelValue;
           }) || {};             
       }

       //update the element with the value that should be shown in the input
       $(element).val(modelValue && inputValueProp !== valueProp ? unwrap(modelValue[inputValueProp]) : modelValue.toString());    
    }
};

您将使用它像：

<input data-bind="jqAuto: { autoFocus: true }, jqAutoSource: myPeople, jqAutoValue: mySelectedGuid, jqAutoSourceLabel: 'displayName', jqAutoSourceInputValue: 'name', jqAutoSourceValue: 'guid'" />