Extracting FBTs

We provide

collectFbt.js as a utility for collecting strings. It expects a JSON input of:

{
  <enumManifestPath>: [
    <path1>, <path2>, ..., <pathN>
  ]
}

collectFbt.js is also exposed as a binary named fbt-collect from babel-plugin-fbt

enumManifestPath doesn't need to point to a valid enum manifest, but if you use a shared enum it's required.

The enum-manifest should be a "JSON.parseable" mapping from all known enums in your app to the key/value pairs they respectively represent:

{
 "EnumA": {
    "keyA1": "valA1",
    ...,
    "keyAN": "valAN"
  },
  ...,
 "EnumX": {
    "keyX1": "valX1",
    ...,
    "keyXM": "valXM"
  },
}

We've provided manifest.js as an easy way to generate this manifest from a given source tree. manifest.js is also exposed as a binary named fbt-manifest from babel-plugin-fbt

collectFbt.js will output a JSON object in the following format:

{
  "phrases": [
    {
      "hashToLeaf": {
        <hash>: {
          "text": <text>,
          "desc": <description>,
        },
        ...
      },
      "line_beg": <beginning_line>,
      "col_beg": <beginning_col>,
      "line_end": <end_line>,
      "col_end": <col_end>,
      "type": "text"|"table",
      "project": <project>,
      "jsfbt": string|{t: <table>, m: <metadata>},
    }
  ],
  childParentMapping: {
    <childIdx>: <parentIdx>
  }
}

phrases here represents all the source information we need to process and produce an fbt._(...) callsite's final payload. When combined with corresponding translations to each hashToLeaf entry we can produce the translated payloads fbt._() expects.

When it comes to moving from source text to translations, what is most pertinent is the hashToLeaf payload containing all relevant texts with their identifying hash. You can provide a custom hash module to collectFbts if you so choose. It defaults to md5.

A note on hashes

In the FBT framework, there are 2 main places we uses hashes for identification: text and fbt callsite. The hashToLeaf mapping above represents the hash (using whichever algorithm was chosen in collectFbt) of the text and its description. This is used when building the translated payloads.

The hash of the callsite (defaulting to jenkins hash) is used to look up the payload in FbtTranslations. This is basically the hash of the object you see in jsfbt.

See Translating FBTs for getting your translations in the right format.

A note on hashes#

A note on hashes