Template variables: dynamically filter dashboards

For custom dashboards, you can use template variables to dynamically filter charts and other widgets. Template variables help make your dashboards more useful, and help you more easily create dashboards you can reuse for different use cases.

Why use template variables?

Template variables are a powerful and dynamic way of filtering an entire dashboard based on specific metadata values a dashboard creator chooses. The benefits of using template variables are:

• They make dashboards easier to use: your users don't have to understand the structure of the data, but can simply choose from various filter options you've set.
• They allow you to create reusable dashboard templates, which you can then duplicate and adjust for many other uses.

Here's an example of a dashboard with several template variables, which you can see at the top of the dashboard.

With template variables, you can set up a wide variety of variables and filters to create the dashboard experience you need. Examples of experiences you can create:

• A dropdown to choose an app name
• A dropdown to choose specific regions
• A dropdown to select specific durations or other numeric values
• Filters that use free text fields to find matching strings

Requirements and limitations

Template variables can only be used in the context of making widgets for custom dashboards. See NRQL variables for using variables in a NRQL query.

Queries with template variables can only be used in the context of a dashboard. For this reason, some query-related features don't work. For example, the Export dashboard as PDF option doesn't support widgets with variables.

Important points to note about adding a query:

• The variable you defined goes inside the {{ … }} brackets.

• The variable generates a string value.

• To help you when you're creating a query, there's a color code:

  • Clauses, from, select, facet, and where, are in pink.
  • Identifiers are in black.
  • Functions are in blue.
  • Strings are in green.
  • Integers are in brown.

• See our How to use NRQL: the mechanics of querying page if you want to know more about writing queries with NRQL.

For restrictions related to writing queries, see Writing queries.

Use template variables

We'll walk you through creating a template variable, and then we'll give you a few examples of different kinds of template variables.

Creating a template variable consists of two steps.

Step 1. Define the template variable

First, you'll define a template variable. This is the variable that you'll use in a NRQL query to create a widget.

To define a variable:

1. From a new dashboard without variables, click the edit button, and then, click + Add variable button located at the top-left corner. Once you've finished adding variables, click Done editing.

   If the dashboard includes widgets, click the + Add variable button.

2. Complete the Add variable workflow. Below are some rules and tips for each of the fields.

Field	Details
Name to use in queries	The name of the variable. This is what you'll use in the query, surrounded by {{...}}. For example, if you use country here as the name, then when writing a query you'll call the variable with {{country}}. Variable names must start with a letter and can contain letters, numbers, and underscores.
Display name	Optional. This is how the variable will display above the dashboard so that dashboard users know what the variable represents. If this is left blank, it will use the main name value.
Type	There are three options: Query: You can write a query that will return a dynamic list of options used in the dropdown menu. For example, the following query would return a dynamic list of country values: SELECT uniques(countryCode) FROM PageAction since 2 days ago Copy For rules and tips on writing queries, see Query-type variables. List: A list of comma-separated values that are used to populate the options in the dropdown menu. For example, you could manually define a list of country values using a list like: ES, US, CA. Text field: Instead of a dropdown of values to choose from, this allows dashboard users to filter for whatever text they input.
Account	Only present for query type. For organizations with multiple accounts, this sets the account that is queried.
Query	Write here your query using uniques (attribute).
Multi-select	Optional. This option allows a dropdown to allow multiple selections at the same time instead of a single selection.
Default values	Optional. These are the defaults value that the dashboard will filter on. For example, if you used the country query above, you could input ES as the default value and the dashboard would automatically filter to that value. You can also select all possibilities. To use multiple values on a WHERE clause you need to use IN instead of =.
Output format	This lets you change how the data generated by the variable is handled in the query. The selected option you choose here is related to the query you're going to add later in the widget. The default option is string because this is the more common option used in the majority of queries. You can change the default option to one of these: String: Use this when the variable will produce a string. Number: Use this when it will product a numeric value. Identifier: Use this when you want to substitute parts of the query, like event names or facet names.

See this example of what a template variable for country values would look like:

Once you've defined your template variable, you can add a widget that uses your created template variable.

Step 2. Create widgets that use the template variable

Once you've configured a template variable, you'll need widgets on a dashboard that use the variable that you've defined in their query.

To create a widget:

1. From your dashboard click + Add widget button located at the top-right corner.

2. There are 2 options:

   • Add a chart. You'll create your widget using the query builder.
   • Add text, images, or links. You'll create your widget adding your own content using our Markdown editor.

3. We choose Add a chart option.

4. Add your query and click Run.

   Following our example mentioned in step 1:

   SELECT countryCode FROM PageAction WHERE countryCode IN ({{countryCode}})

   Copy
   

5. Click Save

When you're done defining a template variable and adding a widget that references that variable, you can verify it's working as expected by choosing different options from the template variable bar and seeing if the widget changes based on your selection.

Here's an example of the resulting widget, on the right, with the country dropdown to the left.

Rules for writing a query-type template variable

As discussed in the section on defining template variables, there are three variable types: query, list, and text field. The query-type variable is the most complex to create because you must create a working query that returns values, which are then used to populate the dropdown in the template variable bar at the top of the dashboard.

Here are some rules and guidance on creating a query-type variable:

• Queries must use the uniques or keyset syntax. Uniques return up to 10,000 results. Check uniques and the keyset. Here's a couple of query examples:

  From PageAction select uniques(countryCode)

  Copy

  From PageView select keyset() SINCE 1 day ago

  Copy

• You can use almost any NRQL query as long as the uniques and keyset components return a list of values.

• Nested variables are not supported: there can't be variables within variables.

Some examples

Here are some different types of template variable implementations.

Use multi-value option

You can enable the multi-value option from the display options section when creating a variable of type NRQL/ENUM.

Here's an example of a query that creates a variable named {{MultiValue}} and returns a list of all unique eventId's:

SELECT uniques(eventId) FROM AjaxRequest

Copy

Then you would create a widget with the following query:

SELECT count(*) FROM AjaxRequest WHERE eventId IN ({{MultiValue}})

Copy

Use multiple variables for one widget

You can define only one template variable at a time, but you can use more than one template variable in a single widget.

Here's an example of a query that uses two template variables. Note that this assumes the countryCode and city template variables would have already been created.

SELECT countryCode, city FROM PageAction WHERE countryCode = {{countryCode}} and city = {{city}}

Copy

Use variables and partial match

Using variables and regex, you can create a filter, provided you're sure that a part of the filter is fixed.

You need to use this partial match if you want to use like.

Let's say you want to filter by release version. The query returns something like: release-1234.

You can create a variable using aparse to parse the version number:

SELECT uniques(aparse(platformVersion , 'release-*')) FROM PageView

Copy

Then create a widget with the following query:

SELECT count(*) FROM PageAction WHERE aparse(platformVersion, 'release-*') IN ({{releaseversion}}) facet platformVersion

Copy

Or if you prefer, you could use the capture command:

SELECT count(*) FROM PageAction WHERE capture(platformVersion, r'release-(?P<platformVersion>\d+)') IN ({{releaseversion}}) Facet platformVersion

Copy

Use variables and regex with LIKE / RLIKE

You can use LIKE and RLIKE as template variables to filter data in a dashboard. To use this feature, the value you add when creating the template variable must use the % wildcard symbols at the start and end of the value.

Here's an example. You define a string variable, as shown here:

You can then create a widget chart and use your variable like this:

FROM NrdbQuery SELECT user WHERE user LIKE {{like_filter}}

Copy

or like this:

FROM NrdbQuery SELECT user WHERE user RLIKE {{like_filter}}

Copy

Use variable facet with a NRQL query

You can create a variable of type NRQL with a string output format and use it after a facet clause to group by different values.

For example, you might create a variable named {{userAgentName}} that would look like:

SELECT uniques(userAgentName) FROM PageAction

Copy

Then you'd create a widget with the following query:

SELECT count(*) FROM PageAction WHERE userAgentName={{userAgentName}} FACET userAgentName

Copy

Use variables for dynamic grouping

You can create a variable with an identifier output format and use it after a FACET clause to group by different values.

For example, you might create a {{location}} variable of type list with two possible values: countryCode and city. You'd set the output format to identifier.

Then you'd create a widget with the following query:

SELECT count(*) FROM PageAction FACET {{location}}

Copy

Use variables to dynamically change the percentile

You can create a variable with output format number and use that inside a percentile function.

For example, you could create a {{percentile}} variable of type list with two possible values: 55 and 90. You'd want to set the output format as number.

Then you'd create a widget with the following query:

SELECT percentile(duration,{{percentile}}) FROM PageAction

Copy

Use variables to filter

To use variables for filtering you only need to add the created variable on the right side of a WHERE clause, like this:

SELECT countryCode, city FROM PageAction WHERE countryCode IN ({{countryCode}})

Copy

If you haven't already, create your free New Relic account below to start monitoring your data today.