Variables

A variable is a placeholder for a value. You can use variables in queries so when you change the value, your queries will be re-ran and the chart or table updated.

• Variables map keys to values.
• Setting Variables
  • These variables can be empty or set to defaults by the author when a dashboard is loaded.
  • User interaction with User Forms or Chart/Grids can set variables
    • User Forms have buttons, text inputs, numeric inputs etc. mapped to author specified keys.
    • Chart automatically populate specially named keys (ts/name/seriesName) when clicked.
    • Tables populate keys named tbl.YYY where YYY is mapped to each column name and the value is the selected rows column value.
• Once a variable is set. Any SQL query containing that variable is sent and the view automatically updated.

Notice in the picture below, the author has added a Debug component. This component shows the value of all keys/values. On the left is a form where the user has chosen EUR/JPY, this causes the variable ccy to map to the value EUR/JPY.

Page Address Importance

The web page address contains the current key/values at all times. You will notice as you set variables either by interacting with forms, charts or tables that the address bar gets updated to contain these vaiables like so:

http://pulseui.net/dash/5/PnL?ccy=EUR%2FJPY&days=2

This has a number of benefits:

• You can bookmark and share a page by emailing the URL.
• When an author saves a dashboard, the current values in the URL are used as defaults when a dashboard is first loaded for other users.

Variable Formatters

Syntax: {{variable_name:format}}

The formatting of the variable normally depends on the data source, but in some situations you might want to override the default formatting. If for example you are trying to generate a query that involves nested quotations.

Format	Description	Examples
raw	Turns off all formatting. No wrapping or escaping. Comma separates multiple values.	A"A,BB,C MINUS
sql	Wrap strings and dates with single-quotes, escape ' with ''. Comma separate multiple values. Enclose within parenthesis (). Detect single numerical values and pass without quotes.	('A"A','BB','C MINUS')
kdb	Wrap strings with double-quotes, escape " with \". Semi-colon separate multiple values. Enclose multiple values within parentheses. Detect single numerical values and pass without quotes. Note You may want to use `${{VARNAME}} to convert the string list to symbols.	("A\"A";"BB";"C MINUS")
csv	Comma separates the values. No wrapping or escaping strings.	A"A,BB,C MINUS
html	HTML encode strings to escape <> as &lt;&gt; etc.	A&quot;A,BB,C MINUS
pipe	Same as CSV but uses pipe | separator.	A"A|BB|C MINUS
json	Wrap strings with double-quotes, escape " with \". Convert multiple values to array [].	["A\"A","BB","C MINUS"]
url	URL encode the CSV version.	%28A%22A%2CBB%2CC%20MINUS%29

Special Variables

Name	value
{{user}}	The login name of the current user viewing the dashboard.
{{e}}	Contains event details. See event handlers for more details.
{{ALL}}	Send all variables that exist as a nested dictionary. Works with kdb+ only.

Example of sending ALL variables to kdb+

d:{{ALL}}; show d; ([] enlist `OK)

Variables Debug Component

The Variables Debug component is a special author tool that makes it easy to see which variables are currently set, what their values are, and how they change in real time as users interact with the dashboard. It is not usually shown to end-users, but is very useful for authors when building and testing dashboards.

When added to a dashboard, the component displays three collapsible sections:

• Globals – A table of all variables currently set. Keys and their values are shown. Recently changed variables are highlighted. Authors can reset individual variables or reset all variables at once.
• Latest Error – Shows the most recent error message received from queries (for example, SQL/kdb+ syntax errors or connection issues).
• Latest Action Event – Displays the most recent query that was sent, the server it was sent to, and the variables passed in at that time.

This makes it very clear how user interactions (form inputs, chart clicks, table selections) map to variable values and how those values flow into queries. If you are debugging a dashboard and something doesn’t look right, check here to confirm the expected keys and values are being set.

Each variable row in the Globals table includes a delete button that lets you clear that variable immediately. Hovering over the delete button shows it in red, making it clear when you are about to remove a variable. You can also use the Reset All button to clear all variables in one action.