2018-06-02 03:56:34 +02:00
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---
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layout: "functions"
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2018-12-20 05:35:11 +01:00
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page_title: "lookup - Functions - Configuration Language"
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2018-06-02 03:56:34 +02:00
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sidebar_current: "docs-funcs-collection-lookup"
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description: |-
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The lookup function retrieves an element value from a map given its key.
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---
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# `lookup` Function
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`lookup` retrieves the value of a single element from a map, given its key.
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If the given key does not exist, a the given default value is returned instead.
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```
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lookup(map, key, default)
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```
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-> For historical reasons, the `default` parameter is actually optional. However,
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omitting `default` is deprecated since v0.7 because that would then be
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equivalent to the native index syntax, `map[key]`.
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## Examples
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```
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> lookup({a="ay", b="bee"}, "a", "what?")
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ay
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> lookup({a="ay", b="bee"}, "c", "what?")
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what?
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```
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## Related Functions
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* [`element`](./element.html) retrieves a value from a _list_ given its _index_.
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