60 lines
1.3 KiB
Markdown
60 lines
1.3 KiB
Markdown
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# Default Functions
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Sprig provides tools for setting default values for templates.
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## default
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To set a simple default value, use `default`:
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```
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default "foo" .Bar
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```
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In the above, if `.Bar` evaluates to a non-empty value, it will be used. But if
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it is empty, `foo` will be returned instead.
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The definition of "empty" depends on type:
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- Numeric: 0
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- String: ""
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- Lists: `[]`
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- Dicts: `{}`
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- Boolean: `false`
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- And always `nil` (aka null)
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For structs, there is no definition of empty, so a struct will never return the
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default.
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## empty
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The `empty` function returns `true` if the given value is considered empty, and
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`false` otherwise. The empty values are listed in the `default` section.
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```
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empty .Foo
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```
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Note that in Go template conditionals, emptiness is calculated for you. Thus,
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you rarely need `if empty .Foo`. Instead, just use `if .Foo`.
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## coalesce
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The `coalesce` function takes a list of values and returns the first non-empty
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one.
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```
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coalesce 0 1 2
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```
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The above returns `1`.
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This function is useful for scanning through multiple variables or values:
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```
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coalesce .name .parent.name "Matt"
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```
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The above will first check to see if `.name` is empty. If it is not, it will return
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that value. If it _is_ empty, `coalesce` will evaluate `.parent.name` for emptiness.
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Finally, if both `.name` and `.parent.name` are empty, it will return `Matt`.
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