Transforms

Transforms

Transforms modify taxonomy values when generating event keys. They’re defined as pipelines of steps.

Defining Transforms

opentp.yaml

spec:
  transforms:
    slug:
      steps:
        - step: lower
        - step: trim
        - step: replace
          params:
            pattern: " "
            with: "_"

Using Transforms

Reference transforms in key patterns:

spec:
  events:
    key:
      pattern: "{area | slug}::{event | slug}"

Multiple transforms can be chained:

pattern: "{area | lower | truncate}::{event | slug}"

Built-in Transforms

lower

Converts string to lowercase.

- step: lower

Input	Output
Hello World	hello world
AUTH	auth

upper

Converts string to uppercase.

- step: upper

Input	Output
hello world	HELLO WORLD
auth	AUTH

trim

Removes leading and trailing whitespace.

- step: trim

Input	Output
hello	hello
auth	auth

replace

Replaces occurrences of a pattern.

- step: replace
  params:
    pattern: " "
    with: "_"

Params	Input	Output
pattern: " ", with: "_"	hello world	hello_world
pattern: "-", with: "_"	my-event	my_event

truncate

Limits string length.

- step: truncate
  params:
    maxLen: 50

Params	Input	Output
maxLen: 10	hello world	hello worl
maxLen: 5	auth	auth

to-snake-case

Converts to snake_case.

- step: to-snake-case

Input	Output
Hello World	hello_world
helloWorld	hello_world
HelloWorld	hello_world

to-kebab

Converts to kebab-case.

- step: to-kebab

Input	Output
Hello World	hello-world
helloWorld	hello-world
HelloWorld	hello-world

to-camel-case

Converts to camelCase.

- step: to-camel-case

Input	Output
hello world	helloWorld
hello_world	helloWorld
Hello World	helloWorld

to-underscore

Replaces spaces with underscores.

- step: to-underscore

Input	Output
hello world	hello_world
hello world	hello__world

collapse

Collapses multiple consecutive characters into one.

- step: collapse
  params:
    char: "_"

Params	Input	Output
char: "_"	hello___world	hello_world
char: " "	hello world	hello world

keep

Keeps only specified characters.

- step: keep
  params:
    chars: "abcdefghijklmnopqrstuvwxyz0123456789_"

Params	Input	Output
chars: "a-z0-9"	hello-123!	hello123

transliterate

Maps characters to replacements.

- step: transliterate
  params:
    map:
      "ä": "ae"
      "ö": "oe"
      "ü": "ue"

Params	Input	Output
map: {"é": "e"}	café	cafe

Common Pipelines

URL-safe slug

slug:
  steps:
    - step: lower
    - step: trim
    - step: replace
      params:
        pattern: " "
        with: "_"
    - step: keep
      params:
        chars: "abcdefghijklmnopqrstuvwxyz0123456789_"

Truncated identifier

short-id:
  steps:
    - step: lower
    - step: to-snake-case
    - step: truncate
      params:
        maxLen: 30

Custom Transforms

Create custom transforms in JavaScript:

my-transforms/reverse/index.js

module.exports = {
  name: 'reverse',
  factory: (params) => (value) => {
    return value.split('').reverse().join('');
  }
};

Load with CLI:

opentp validate --external-transforms ./my-transforms

Or in config:

opentp.yaml

spec:
  external:
    transforms: ./my-transforms