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A collection of helpers for handlebars (rust) to manage string, json, yaml, toml, path, file, http request.

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handlebars_misc_helpers

crates license crate version Documentation

Project Status: WIP – Initial development is in progress, but there has not yet been a stable, usable release suitable for the public. Actions Status test coverage

A collection of helpers for handlebars (rust) to manage String, JSON, YAML, TOML, path, file, and HTTP requests.

Helpers extend the template to generate or transform content. Few helpers are included, but if you need more helpers, ask via an issue or a PR.

To use a helper:

// arguments are space separated
{{ helper_name arguments}}

To chain helpers, use parenthesis:

{{ to_upper_case (to_singular "Hello foo-bars") }}
// -> BAR

{{ first_non_empty (unquote (json_str_query "package.edition" (read_to_str "Cargo.toml") format="toml")) (env_var "MY_VERSION") "foo" }}
// -> 2018

see Handlebars templating language

To not "import" useless dependencies, use the crate's features:

default = ["string", "http_attohttpc", "json", "jsonnet", "regex", "uuid"]
http_attohttpc = ["dep:attohttpc"]
http_reqwest = ["dep:reqwest"]
json = [
    "dep:jmespath",
    "dep:serde",
    "dep:serde_json",
    "dep:serde_yaml",
    "dep:toml",
]
jsonnet = ["dep:jsonnet-rs"]
jsontype = ["dep:serde_json"]
regex = ["dep:regex"]
string = ["dep:cruet", "dep:enquote", "jsontype"]
uuid = ["dep:uuid"]

String transformation

helper signature usage sample sample out
replace s:String from:String to:String replace "Hello old" "old" "new" "Hello new"
to_lower_case s:String to_lower_case "Hello foo-bars" "hello foo-bars"
to_upper_case s:String to_upper_case "Hello foo-bars" "HELLO FOO-BARS"
to_camel_case s:String to_camel_case "Hello foo-bars" "helloFooBars"
to_pascal_case s:String to_pascal_case "Hello foo-bars" "HelloFooBars"
to_snake_case s:String to_snake_case "Hello foo-bars" "hello_foo_bars"
to_screaming_snake_case s:String to_screaming_snake_case "Hello foo-bars" "HELLO_FOO_BARS"
to_kebab_case s:String to_kebab_case "Hello foo-bars" "hello-foo-bars"
to_train_case s:String to_train_case "Hello foo-bars" "Hello-Foo-Bars"
to_sentence_case s:String to_sentence_case "Hello foo-bars" "Hello foo" bars
to_title_case s:String to_title_case "Hello foo-bars" "Hello Foo Bars"
to_class_case s:String to_class_case "Hello foo-bars" "HelloFooBar"
to_table_case s:String to_table_case "Hello foo-bars" "hello_foo_bars"
to_plural s:String to_plural "Hello foo-bars" "bars"
to_singular s:String to_singular "Hello foo-bars" "bar"
to_foreign_key s:String to_foreign_key "Hello foo-bars" "hello_foo_bars_id"
demodulize s:String demodulize "Test::Foo::Bar" "Bar"
ordinalize s:String+ ordinalize "9" "9th"
deordinalize s:String+ deordinalize "9th" "9"
trim s:String trim " foo " "foo"
trim_start s:String trim_start " foo " "foo "
trim_end s:String trim_end " foo " " foo"
unquote s:String unquote "\"foo\"" "foo"
enquote symbol:String s:String enquote "" "foo" "\"foo\""
first_non_empty s:String+ first_non_empty "" null "foo" "bar" "foo"

Regular expression

usage output
{{ regex_is_match pattern="(?<first>\\w)(\\w)(?:\\w)\\w(?<last>\\w)" on="today" }} true
{{#if (regex_is_match pattern="(?<first>\\w)(\\w)(?:\\w)\\w(?<last>\\w)" on="today" ) }}ok{{/if}} ok
{{ regex_captures pattern="(?<first>\\w)(\\w)(?:\\w)\\w(?<last>\\w)" on="today" }} [object]
{{ json_to_str( regex_captures pattern="(?<first>\\w)(\\w)(?:\\w)\\w(?<last>\\w)" on="today" ) }} {"_0":"today","_1":"t","_2":"o","_3":"y","first":"t","last":"y"}
{{ set captures=( regex_captures pattern="(?<first>\\w)(\\w)(?:\\w)\\w(?<last>\\w)" on="today" ) }}{{ captures.last }} y

UUID

usage output
{{ uuid_new_v4 }} 6db4d8a7-8117-4b72-9dbc-988e6ee2a6e3
{{ len (uuid_new_v4) }} 36
{{ uuid_new_v7 }} 94d7bb75-9b16-40dd-878d-5fbb37b8ae2c
{{ len (uuid_new_v7) }} 36

HTTP content

The helpers can render the body's response from an HTTP request.

helper signature usage sample
http_get url:String http_get "http://hello/..."
gitignore_io templates:String gitignore_io "rust,visualstudiocode"

Path extraction

Helper able to extract (or transform) path (defined as string).

for the same input: "/hello/bar/foo.txt"

helper_name sample output
file_name "foo.txt"
parent "/hello/bar"
extension "txt"

File

Helper to read file content.

usage output
{{ read_to_str "/foo/bar" }} content of file /foo/bar
{{ read_to_str "file/does/not/exist" }} empty string

Environment variable

The helper can get environment variables.

helper_name usage
env_var env_var "HOME"

Some special environment variables are predefined (some of them come from std::env::consts - Rust):

variable possible values
"ARCH"
  • x86
  • x86_64
  • arm
  • aarch64
  • mips
  • mips64
  • powerpc
  • powerpc64
  • s390x
  • sparc64
"DLL_EXTENSION"
  • so
  • dylib
  • dll
"DLL_PREFIX"
  • lib
  • "" (an empty string)
"DLL_SUFFIX"
  • .so
  • .dylib
  • .dll
"EXE_EXTENSION"
  • exe
  • "" (an empty string)
"EXE_SUFFIX"
  • .exe
  • .nexe
  • .pexe
  • "" (an empty string)
"FAMILY"
  • unix
  • windows
"OS"
  • linux
  • macos
  • ios
  • freebsd
  • dragonfly
  • netbsd
  • openbsd
  • solaris
  • android
  • windows
"USERNAME" try to find the current username, in the order:
  1. environment variable "USERNAME"
  2. environment variable "username"
  3. environment variable "USER"
  4. environment variable "user"

JSON & YAML & TOML

Helpers

  • json_query query:String data:Json: Helper able to extract information from JSON using JMESPath syntax for query.
  • json_str_query query:String data:String: Helper able to extract information from JSON using JMESPath syntax for query, data follows the requested format.
  • json_to_str data:Json: convert JSON data into a string following the requested format.
  • str_to_json data:String: convert(parse) a string into a JSON following the requested format.

The optional requested format, is the format of the string with data:

  • "json" (default if omitted)
  • "json_pretty" JSON with indentation,...
  • "yaml"
  • "toml"
  • "toml_pretty"
usage output
{{ json_query "foo" {} }} ``
{{ json_to_str ( json_query "foo" {"foo":{"bar":{"baz":true}}} ) }} {"bar":{"baz":true}}
{{ json_to_str ( json_query "foo" (str_to_json "{\"foo\":{\"bar\":{\"baz\":true}}}" ) ) }} {"bar":{"baz":true}}
{{ json_str_query "foo" "{\"foo\":{\"bar\":{\"baz\":true}}}" }} {"bar":{"baz":true}}
{{ json_str_query "foo.bar.baz" "{\"foo\":{\"bar\":{\"baz\":true}}}" }} true
{{ json_str_query "foo" "foo:\n bar:\n baz: true\n" format="yaml"}} bar:\n baz: true\n
{{ json_to_str ( str_to_json "{\"foo\":{\"bar\":{\"baz\":true}}}" format="json") format="yaml"}} foo:\n bar:\n baz: true\n

Blocks

{{#from_json format="toml"}}
{"foo": {"hello":"1.2.3", "bar":{"baz":true} } }
{{/from_json}}

[foo]
hello = "1.2.3"

[foo.bar]
baz = true
 
{{#to_json format="toml"}}
[foo]
bar = { baz = true }
hello = "1.2.3"
{{/to_json}}
 
{
  "foo": {
    "bar": {
      "baz": true
    },
    "hello": "1.2.3"
  }
}
 
{{#from_json format="yaml"}}
{"foo":{"bar":{"baz":true}}}
{{/from_json}}
 
foo:
  bar:
    baz: true
 
{{#to_json format="yaml"}}
foo:
    bar:
        baz: true
{{/to_json}}
 
{
  "foo": {
    "bar": {
      "baz": true
    }
  }
}

Note: YAML & TOML content are used as input and output formats for JSON data. So capabilities are limited to what JSON support (eg. no date-time type like in TOML).

Edition via Jsonnet

For a more advanced edition of JSON, you can use Jsonnet.

A data templating language for app and tool developers

  • See the doc of jsonnet for more samples, and syntax info,...
  • This block can be combined with conversion helper/block for YAML & TOML to provide edition capabilities for those format
  • the output should be a valid JSON, except if string_output = false is set as a parameter of the block.
{{#jsonnet}}
local v = {"foo":{"bar":{"baz":false}}};
v {
  "foo" +: {
      "bar" +: {
          "baz2": true
      }
  }
}
{{/jsonnet}}
 
{
  "foo": {
      "bar": {
          "baz": false,
          "baz2": true
      }
  }
}

Assign, set

The helpers can assign a variable to use later in the template.

⚠️ assign is deprecated and replaced by set (more compact and allows multiple assignments in one call)

usage output
{{ assign "foo" "hello world" }}{{ foo }} hello world
{{ set foo="{}" }} ``
{{ set foo="{}" }}{{ foo }} {}
{{ set foo="hello world" }}{{ foo }} hello world
{{ set foo={} }}{{ foo }} [object]
{{ set foo={"bar": 33} }}{{ foo }} [object]
{{ set foo={"bar": 33} }}{{ foo.bar }} 33
{{ set foo="world" bar="hello" }}>{{ bar }} {{ foo }}< >hello world<
{{ set foo="world" }}{{ set bar="hello" }}>{{ bar }} {{ foo }}< >hello world<

Replace section

This helper can replace a section delimited by a boundary.

For example with this template:

{{~#replace_section  begin="<!-- #region head-->" end="<!-- #endregion head -->" content }}
This is the new content of the block
{{~/replace_section}}

The content having

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <!-- #region head-->
    Something by default
    <!-- #endregion head -->
  </body>
</html>

The content between <!-- #region head--> and <!-- #endregion head --> is replaced by the result of the inner template:

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <!-- #region head-->This is the new content of the block<!-- #endregion head -->
  </body>
</html>

Note: you can remove the boundary by adding remove_boundaries=true.

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A collection of helpers for handlebars (rust) to manage string, json, yaml, toml, path, file, http request.

crates.io/crates/handlebars_misc_helpers

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