MultiDropdownList

MultiDropdownList creates a dropdown based multiple selection list UI component that is connected to a database field. It is used for filtering results based on the current selection from a list of items.

Note

This component is exactly like the MultiList component except the UI is based on a dropdown, ideal for showing additional UI filters while conserving screen space.

Example uses:

• create an e-commerce facet like search experience.
• create a filter for airlines to fly by in a flight booking experience.

Usage

Basic Usage

<template>
	<multi-dropdown-list
        componentId="CitySensor"
        dataField="group.group_city.raw"
        title="Cities"
    />
</template>

Usage With All Props

<multi-dropdown-list
	componentId="CitySensor"
	dataField="group.group_city.raw"
	title="Cities"
	sortBy="count"
	placeholder="Search City"
	filterLabel="City"
	:defaultValue="['London']"
	:showCount="true"
	:size="100"
	:react="{ and: ['CategoryFilter', 'SearchFilter'] }"
	:showFilter="true"
	:URLParams="false"
/>

Props

• componentId String unique identifier of the component, can be referenced in other components' react prop.

• dataField String DB data field to be mapped with the component's UI view. The dropdown list items are filtered by a database query on this field. This field is used for doing an aggregation and returns the result. We're using a .raw multifield here. You can use a field of type keyword or not_analyzed depending on your Elasticsearch cluster.

• nestedField String [optional] use to set the nested mapping field that allows arrays of objects to be indexed in a way that they can be queried independently of each other. Applicable only when dataField is a part of nested type.

• title String or JSX [optional] title of the component to be shown in the UI.

• size Number [optional] number of list items to be displayed.

  Note:

  1. Appbase users should use the aggregationSize prop instead. The size prop would only set the size for hits not the aggregations.
  2. We recommend Appbase users to not use the size prop unless they are using hits because it can impact the query performance.

• aggregationSize To set the number of buckets to be returned by aggregations.

  Note: This prop is only applicable when enableAppbase is set to true.

• sortBy String [optional] property that decides on how to sort the list items, accepts one of count, asc or desc as valid values.

  • count sorts the list based on the count occurences, with highest value at the top.
  • asc sorts the list in the ascending order of the list item (Alphabetical).
  • desc sorts the list in the descending order of the term. Defaulted to count.

• defaultValue Array [optional] pre-select one or more options from the dropdown list. Accepts an Array object containing the items that should be selected. It is important for the passed value(s) exactly match with the field value(s) as stored in appbase.io app.

• value Array<String> [optional] sets the current value of the component. It sets the value (on mount and on update). Use this prop in conjunction with the change event.

• queryFormat String [optional] queries the selected items from the list in one of two modes: or, and.

  • Defaults to or which queries for results where any of the selected list items are present.
  • In and mode, the applied query filters results where all of the selected items are present.

• showCount Boolean [optional] show count of number of occurences besides an item. Defaults to true.

• showSearch Boolean [optional] whether to show a searchbox to filter the list items locally. Defaults to false.

• showClear Boolean [optional] whether to show a clear button to clear the entered text in the searchbox. Defaults to false.

• render Function|slot-scope [optional] an alternative callback function to renderItem, where user can define how to render the view based on all the data changes.
  It accepts an object with these properties:

  • loading: boolean indicates that the query is still in progress
  • error: object An object containing the error info
  • data: array An array of results obtained from the applied query.
  • rawData object An object of raw response as-is from elasticsearch query.
  • value: array current selected values.
  • handleChange: function A callback function can be used to mark the list value as selected.
  • downshiftProps: object provides the following control props from downshift which can be used to bind list items with click/mouse events.
    • isOpen boolean Whether the menu should be considered open or closed. Some aspects of the downshift component respond differently based on this value (for example, if isOpen is true when the user hits "Enter" on the input field, then the item at the highlightedIndex item is selected).
    • getItemProps function Returns the props you should apply to any menu item elements you render.
    • getItemEvents function Returns the events you should apply to any menu item elements you render.
    • highlightedIndex number The index that should be highlighted.

You can use render as a slot as shown below:

<multi-dropdown-list
    :showSearch="false"
    componentId="BookSensor"
    data-field="original_series.raw"
>
	<div
		class="suggestions"
		slot="render"
		slot-scope="{ data, handleChange, downshiftProps: { isOpen } }"
	>
		<ul v-if="isOpen">
			<li
				style="{ background-color: highlightedIndex ? 'grey' : 'transparent' }"
				v-for="suggestion in (data || [])"
				:key="suggestion._id"
				v-on:click="handleChange(suggestion.key)"
			>
				{{ suggestion.key }}
			</li>
		</ul>
	</div>
</multi-dropdown-list>

• renderItem Function|slot-scope [optional] customize the rendered list via a function or slot-scope which receives the item label, count and isChecked & expects a JSX or String back. For example:

<multi-dropdown-list>
	<div
        slot="renderItem"
        slot-scope="{ label, count }"
    >
		{{label}}
		<span :style="{ marginLeft: 5, color: 'dodgerblue' }">
			{{count}}
		</span>
	</div>
</multi-dropdown-list>

• renderLabel Function|slot-scope [optional] can be used to change the label of the dropdown. Useful for adding highlighting/styling to or translating the label.

  Copy

  <multi-dropdown-list>
  	<div
          slot="renderLabel"
          slot-scope="items"
      >
  		<ul>
  			<li v-for="item in items">
  				<div style="{ fontSize: '15px', fontColor: 'blue' }">
                      {{item}}}
                  </div>
  			</li>
  		</ul>
  	</div>
  </multi-dropdown-list>

• renderError String|Function|slot-scope [optional] can be used to render an error message in case of any error.

<template
    slot="renderError"
    slot-scope="error"
>
	<div>Something went wrong!<br />Error details<br />{{ error }}</div>
</template>

• renderNoResults String|Function|slot-scope [optional] show custom message or component when no results found.

<template
    slot="renderNoResults"
>
	<h4>No Results Found!</h4>
</template>

<!-- or -->

<multi-dropdown-list
	...
	:renderNoResults="renderNoResults"
/>

export default {
	...,
	method: {
		renderNoResults() {
			return 'Try Again';
		}
	},
}

• transformData Function [optional] allows transforming the data to render inside the list. You can change the order, remove, or add items, tranform their values with this method. It provides the data as param which is an array of objects of shape { key: <string>, doc_count: <number> } and expects you to return the array of objects of same shape.
• showMissing Boolean [optional] defaults to false. When set to true it also retrives the aggregations for missing fields under the label specified by missingLabel.
• missingLabel String [optional] defaults to N/A. Specify a custom label to show when showMissing is set to true.
• placeholder String [optional] placeholder to be displayed in the dropdown searchbox.
• showFilter Boolean [optional] show as filter when a value is selected in a global selected filters view. Defaults to true.
• filterLabel String [optional] An optional label to display for the component in the global selected filters view. This is only applicable if showFilter is enabled. Default value used here is componentId.
• URLParams Boolean [optional] enable creating a URL query string parameter based on the selected value of the list. This is useful for sharing URLs with the component state. Defaults to false.
• showLoadMore Boolean [optional] defaults to false and works only with elasticsearch >= 6 since it uses composite aggregations. This adds a "Load More" button to load the aggs on demand combined with the size prop. Composite aggregations are in beta and this is an experimental API which might change in a future release.
• isOpen Boolean [optional] When set to true the dropdown is displayed on the initial render. Defaults to false.

Demo

Styles

MultiDropdownList component supports innerClass prop with the following keys:

• title
• select
• list
• icon
• count

Read more about it here.

Extending

MultiDropdownList component can be extended to

1. customize the look and feel with className,
2. update the underlying DB query with customQuery & defaultQuery,
3. connect with external interfaces using beforeValueChange, value-change and query-change,
4. specify how options should be filtered or updated using react prop.

<template>
	<multi-dropdown-list
		className="custom-class"
		:customQuery="getCustomQuery"
		:react="react"
		:beforeValueChange="handleBeforeValueChange"
		@value-change="handleValueChange"
		@query-change="handleQueryChange"
	/>
</template>
<script>
	export default {
		name: 'app',
		methods: {
			getCustomQuery: (value, props) => {
				return {
					query: {
						match: {
							data_field: 'this is a test',
						},
					},
				};
			},
			handleBeforeValueChange: value => {
				// called before the value is set
				// returns a promise
				return new Promise((resolve, reject) => {
					// update state or component props
					resolve();
					// or reject()
				});
			},
			handleValueChange: value => {
				console.log('current value: ', value);
				// set the state
				// use the value with other js code
			},
			handleQueryChange: (prevQuery, nextQuery) => {
				// use the query with other js code
				console.log('prevQuery', prevQuery);
				console.log('nextQuery', nextQuery);
			},
		},
		computed: {
			react() {
				return {
					and: ['pricingFilter', 'dateFilter'],
					or: ['searchFilter'],
				};
			},
		},
	};
</script>

• className String CSS class to be injected on the component container.

• customQuery Function takes value and props as parameters and returns the data query to be applied to the component, as defined in Elasticsearch Query DSL. Note: customQuery is called on value changes in the MultiDropdownList component as long as the component is a part of react dependency of at least one other component.

• defaultQuery Function takes value and props as parameters and returns the data query to be applied to the source component, as defined in Elasticsearch Query DSL. Note: defaultQuery doesn't get leaked to other components.

• beforeValueChange Function is a callback function which accepts component's future value as a parameter and returns a promise. It is called everytime before a component's value changes. The promise, if and when resolved, triggers the execution of the component's query and if rejected, kills the query execution. This method can act as a gatekeeper for query execution, since it only executes the query after the provided promise has been resolved.

  Note:

  If you're using Reactivesearch version >= 1.1.0, beforeValueChange can also be defined as a synchronous function. value is updated by default, unless you throw an Error to reject the update. For example:

  Copy

  beforeValueChange = values => {
  	// The update is accepted by default
  	if (values.includes('Dirk Pitt')) {
  		// To reject the update, throw an error
  		throw Error('Selected values should not include Dirk Pitt.');
  	}
  };

• react Object specify dependent components to reactively update MultiDropdownList's options.

  • key String one of and, or, not defines the combining clause.
    • and clause implies that the results will be filtered by matches from all of the associated component states.
    • or clause implies that the results will be filtered by matches from at least one of the associated component states.
    • not clause implies that the results will be filtered by an inverse match of the associated component states.
  • value String or Array or Object
    • String is used for specifying a single component by its componentId.
    • Array is used for specifying multiple components by their componentId.
    • Object is used for nesting other key clauses.

• index String [optional] The index prop can be used to explicitly specify an index to query against for this component. It is suitable for use-cases where you want to fetch results from more than one index in a single ReactiveSearch API request. The default value for the index is set to the app prop defined in the ReactiveBase component.

  Note: This only works when enableAppbase prop is set to true in ReactiveBase.

Events

• change is an event that accepts component's current value as a parameter. It is called when you are using the value prop and the component's value changes. This event is useful to control the value updates of search input.

  Copy

  <template>
      <multi-dropdown-list
          // ...other props
          value="value"
          @change="handleChange"
      />
  </template>
  
  <script>
  export default {
    name: 'app',
      data() {
          return {
              value: []
          }
      },
      methods: {
          handleChange(value) {
              this.value = value;
          }
      }
  };
  </script>

• query-change is an event which accepts component's prevQuery and nextQuery as parameters. It is called everytime the component's query changes. This event is handy in cases where you want to generate a side-effect whenever the component's query would change.

• value-change is an event which accepts component's current value as a parameter. It is called everytime the component's value changes. This event is handy in cases where you want to generate a side-effect on value selection. For example: You want to show a pop-up modal with the valid discount coupon code when a list item is selected in a "Discounted Price" SingleList.

• error gets triggered in case of an error and provides the error object, which can be used for debugging or giving feedback to the user if needed.