Codegen

Demo

codegen is a command line utility that transforms Go templates from a provided input directory, using variables defined in a configuration file (gen.config.json), and then writes the output to a provided output directory.

Go is not required to be installed, just that the templates are written using Go template engine syntax and use the .gtpl extension.

---

gen.config.json

gen.config.json is the configuration file used by the codegen CLI and must be present in the directory in which codegen is executed and defines information about all template directories, output, and injected variables.

Properties

• templates (array) *required - Defines all templates that can be transformed
  • name (string) *required - The unique name of the template
  • inDir (string) *required - The directory where the template files reside
  • ourDir (string) *required - The directory where the transformed template will be output
  • variables (object) - Variables that will be injected into each template file

---

Example

gen.config.json

{
  "templates": [
    {
      "name": "interface",
      "inDir": "../../templates/interface",
      "outDir": "../../sandbox",
      "variables": {
        "TYPE": "UpcomingMovie",
        "PROPS": [
          {
            "name": "Name",
            "type": "string"
          },
          {
            "name": "Rating",
            "type": "string"
          },
          {
            "name": "LengthInMinutes",
            "type": "number"
          },
          {
            "name": "ReleaseDate",
            "type": "Date"
          }
        ]
      }
    }
  ]
}

Command (ran from directory containing config file):

codegen interface

Reads: ../templates/interface/models/{{.TYPE | ToLowerCamel}}.ts.gtpl

export interface {{.TYPE | ToCamel }} {
{{ range $val := .PROPS -}}
  {{$val.name | ToLowerCamel }}: {{$val.type}};
{{ end }}
}

Outputs: ./models/upcomingMovie.ts

export interface UpcomingMovie {
  name: string;
  rating: string;
  lengthInMinutes: number;
  releaseDate: Date;
}

---

Template Helper Functions

Some helper functions are provided to make transforming variables easier.

String helpers

Function	Input	Output	Usage
ToLower	AnyKind_of-STRING	anykindofstring	{{.MyString | ToLower}}
ToKebab	AnyKind_of-STRING	any-kind-of-string	{{.MyString | ToKebab}}
ToScreamingKebab	AnyKind_of-STRING	ANY-KIND-OF-STRING	{{.MyString | ToScreamingKebab}}
ToSnake	AnyKind_of-STRING	any_kind_of_string	{{.MyString | ToSnake}}
ToScreamingSnake	AnyKind_of-STRING	ANY_KIND_OF_STRING	{{.MyString | ToScreamingSnake}}
ToCamel	AnyKind_of-STRING	AnyKindOfString	{{.MyString | ToCamel}}
ToLowerCamel	AnyKind_of-STRING	anyKindOfString	{{.MyString | ToLowerCamel}}
Pluralize	Person	People	{{.MyString | Pluralize}}

Array helpers

IsLast - determine if an index is the last index in an array

Example:

{{ $arrayLength := len .SomeArrayVariable }}
{{- range $i, $val := .SomeArrayVariable -}}
  {{- if (IsLast $i $arrayLength) -}}
    {{$val}} is the last element
  {{ end }}
{{- end }}

Misc Notes

• Templates may contain nested folders. The output will retain this folder structure relative to the outDir
• Template file and folder names may contain template syntax, i.e {{ .SomeVariable | ToSnake }}.py