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25 lines
1.5 KiB
Markdown
25 lines
1.5 KiB
Markdown
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title = "Variable syntax"
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keywords = ["grafana", "templating", "documentation", "guide", "template", "variable"]
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aliases = ["/docs/grafana/latest/reference/templating"]
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weight = 100
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# Variable syntax
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Panel titles and metric queries can refer to variables using two different syntaxes:
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- `$varname`
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This syntax is easy to read, but it does not allow you to use a variable in the middle of a word.
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**Example:** apps.frontend.$server.requests.count
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- `${var_name}` Use this syntax when you want to interpolate a variable in the middle of an expression.
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- `${var_name:<format>}` This format gives you more control over how Grafana interpolates values. Refer to [Advanced variable format options]({{< relref "advanced-variable-format-options.md" >}}) for more detail on all the formatting types.
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- `[[varname]]` Do not use. Deprecated old syntax, will be removed in a future release.
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Before queries are sent to your data source the query is _interpolated_, meaning the variable is replaced with its current value. During
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interpolation, the variable value might be _escaped_ in order to conform to the syntax of the query language and where it is used.
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For example, a variable used in a regex expression in an InfluxDB or Prometheus query will be regex escaped. Read the data source specific
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documentation topic for details on value escaping during interpolation.
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For advanced syntax to override data source default formatting, refer to [Advanced variable format options]({{< relref "advanced-variable-format-options.md" >}}).
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