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Introduction

Some components, like Visualizations, allow you to use and display the results of queries, which can be executed using dynamic parameters. For more information, read about query parameters. Every Latitude view has a set of global parameters defined in the URL. When using components that run queries, all of these parameters are automatically passed to the query.

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URL Parameters

Global parameters can be both seen and set in the URL of the view, as regular URL parameters. URL parameters are defined by the ? character at the end of the URL, followed by a list of key-value pairs separated by the & character. Each key-value pair is separated by the = character. For example: ?key1=value1&key2=value2&key3=value3

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Example

Let’s see an example:
  1. Create a query with a parameter:
    user_friends.sql
    SELECT * FROM friends WHERE user_id = {param('id')}
    In this query, we are using a parameter called id to filter the results. Check out query parameters for more information.
  2. Create a view displaying the results:
    friends.html
    <Table query="user_friends" />
    Here, we are using the Table component to display the results of the query. We have specified the query to use, but we do not have to specify any parameter, as all global parameters are automatically passed to the query.
  3. Set the parameter in the URL: Now, if we want to see the results for a specific user, we just need to set the id parameter in the URL. For example, if we want to see the friends of the user with id = 1, we can set the URL to: 
    https://latitude.example.com/friends?id=1

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Parameter types in the URL

Parameters in the URL are always treated as strings by default, and they are sent to the query as strings. If you need to use a parameter as a different type, you can specify the type in the URL with the following syntax: parameter=$type:value Where type is the type of the parameter, like text, num, bool or date. Following the previous example, if we want to set the id parameter as a number, we can set the URL to: 
https://latitude.example.com/friends?id=$num:1

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Modifying Global Parameters

Some components will allow you to modify the global parameters directly from the view. For example, the Input component allows you to set a global parameter when the user types in the input field. Check out the Components section to find more information.