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Introduction

The Select component is used to create a dropdown with predefined options for a parameter. This can be useful when you want to provide a list of options for a parameter that the user can choose from, either to limit the possible values or to make it easier for the user to select a value. This component can be used both with predefined options and with dynamic options that are loaded from a query result.

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Options

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Predefined options

The most basic usage of a Select is to provide a list of options that the user can choose from. You can do this by using the options prop to specify an array of options. 
<Select
	param="user_name"
	options={["Alice", "Bob", "Charlie"]}
/>
You can also use different values for the options than what is displayed in the dropdown by using an array of objects with value and label properties. 
<Select
	param="user_id"
	options={[
		{ value: 1, label: "Alice" },
		{ value: 2, label: "Bob" },
		{ value: 3, label: "Charlie" }
	]}
/>
In this example, the value property is what will be used when running any queries using the parameter, while the label property is just what will be displayed in the dropdown.

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Dynamic options

You can also use a query to load the options dynamically. This can be useful when you have a large number of options, when the options change frequently or when you want to filter the options based on other parameters. 
<Select
	param="user_id"
	query="users"
/>
Here, query_name is the name of a query that will be ran to load the options. If the results of the query contain a value and a label property, those will be used as the value and label for the options. Otherwise, the first column will be used as both. If you want to use a different column as the value, you can specify the values and labels props to do so. 
<Select
	param="user_id"
	query="users"
	values="id"
	labels="name"
/>
Like with any visualization, where you use a query to load information, you can also use Inline Parameters and Reactive Params options to modify how the query behaves. For more information on how the query is configured in the view, check out the Running queries section.

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Mixed options

You can mix both predefined and dynamic options by using the options and query props together. The dropdown will first show the predefined options and then load the dynamic options. 
<Select
	param="category_filter"
	options={[
		{ value: false, label: "Any category" }
	]}
	query="categories"
/>

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Default value

You can also add a default value to the dropdown by using the value prop. This will preselect the option with the given value when the page is loaded, if it is not overridden by a value in the URL. 
<Select
	param="user_id"
	options={[
		{ value: 1, label: "Alice" },
		{ value: 2, label: "Bob" },
		{ value: 3, label: "Charlie" }
	]}
	value={2}
/>
If you have a large number of options, you can enable a search box to make it easier for the user to find the option they are looking for. You can do this by adding the searchable prop. 
<Select
	param="city_id"
	query="cities"
	searchable
/>

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Text customization

You can customize the text that is displayed in the dropdown with the following options: label, description and placeholder.
  • label is the text that is displayed above the dropdown.
  • description is the text that is displayed below the dropdown.
  • placeholder is the text that is displayed in the dropdown when no option is selected.
<Select
	param="city_id"
	query="cities"
	label="Select a city"
	description="Choose the city you want to filter by."
	placeholder="Select a city..."
/>

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Multiple selection

You can also allow multiple selections by adding the multiple prop. This will display a checkbox next to each option that the user can select. 
<Select
	query="cities"
	param="city_ids"
	multiple
/>
When multiple selections are enabled, the parameter value will be an array of selected values. You can iterate over this array using the {#each} block in your queries. 
SELECT *
FROM cities
WHERE
{#each param('city_ids') as city, index}
	{#if index > 0} OR {/if}
	id = {city}
{/each}
Check out Queries Loops for more information on how to iterate over arrays in queries.