Template Helpers

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Helpers

In addition to Go’s text/template defaults, hof adds the following functions

There are a number of additional helpers provided.

Notes:

• Many of these are based on the Go stdlib functions with the same name.
• Args can be literal, a .Variable, or the result of another function. See Go’s documentation
• It can be advantageous to do as many manipulations in CUE rather than in the template system.

text/template documentation can be found here: https://pkg.go.dev/text/template

Encode to a data format:

• json ({{ json .Data }})
• yaml ({{ yaml .Data }})
• toml ({{ toml .Data }})
• xml ({{ xml .Data }})

Value helpers:

• dict ({{ ... (dict "key1" "val1" "key2" .Value ...) }}) - create a map on the fly, useful for passing multiple values to partials
• lookup ({{ lookup "path.to.value" .Value }}) - returns the value at hofstadter-io/dotpath from the given value
• pretty ({{ pretty .Value }}) uses https://github.com/kr/pretty
• printf ({{ printf "%s %d" .String .Number }})

Casings conversion helpers:

• lower ({{ lower .String }}) (lowercase)
• upper ({{ upper .String }}) (UPPERCASE)
• title ({{ title .String }}) (Titlecasestring
• pascal ({{ pascal .String }}) (PascalCaseString)
• camel ({{ camel .String }}) (camelCaseString)
• Camel ({{ Camel .String }}) (camel + title)
• snake ({{ snake .String }}) (snake_case_string)
• SNAKE ({{ SNAKE .String }}) (SNAKE_CASE_STRING)
• kebab ({{ kebab .String }}) (kebab-case-string)
• KEBAB ({{ KEBAB .String }}) (KEBAB-CASE-STRING)

String processing helpers:

• concat ({{ concat "foo" "bar" }})
• join ({{ join ", " "foo" "bar" }})
• contains ({{ contains .String .Substr }})
• split ({{ split .String .Separator }})
• replace ({{ replace .String .Old .New .Count }})
• hasprefix ({{ hasprefix .String .Prefix }})
• hassuffix ({{ hassuffix .String .Suffix }})
• trimprefix ({{ trimprefix .String .Prefix }})
• trimsuffix ({{ trimsuffix .String .Suffix }})
• trimto (alias for trimto_first)
• trimfrom (alias for trimfrom_first)
• trimto_first ({{ trimto_first .String .Substr .Keep }}) Trim a string until the first Substring, possibly keeping the substring
• trimfrom_first ({{ trimfrom_first .String .Substr .Keep }})
• trimto_last ({{ trimto_last .String .Substr .Keep }})
• trimfrom_last ({{ trimfrom_last .String .Substr .Keep }})
• substr ({{ substr .String .StartInt .EndInt }})
• getprefix ({{ getprefix .String .Substr }}) (opposite of trimprefix)
• getsuffix ({{ getsuffix .String .Substr }})
• getbetween ({{ getbetween .String .LhsSubstr .RhsSubstr }})

The indent helper is disucssed in the section on indentation.

Other helpers:

• identity ({{ identity .Value }}) - returns Value, ah maths
• gokind ({{ gokind .Value }}) - returns the Go reflect.Kind as a string
• builtin ({{ builtin }}) - returns true if the string is a known Go builtin
• file ({{ file "path/to/file.txt" }}) - loads a file from disk
• render ({{ $content := render "partial-name" <context> }}) - render a partial template to a variable