What is Auto Parameterization?

The basics

<fbt> will automatically wrap any non-fbt children in the top-level <fbt> as though they were written with an <fbt:param> with a name attribute containing the child's text. It will pull any child text into the parameter name, including those of recursive structures.

• HTML fbt syntax:

<fbt desc="auto-wrap example">

Go on an

<a href="#">

<span>awesome</span> vacation

</a>

</fbt>

• Function syntax:

fbt(

[

'Go on an ',

\fbt\createElement(

'a',

'<span>awesome</span> vacation',

['href' => '#']

)

],

'auto-wrap example',

);

When extracted for translation, the result of the \fbt\Transform\FbtTransform\FbtTransform::toArray() is:

[

"phrases" => [

2 => [

"hashToText" => [

"576c64dce7dc0eb30803b1c2feb21722": "Go on an {=awesome vacation}"

],

"desc": "auto-wrap example",

...,

],

1 => [

"hashToText" => [

"7de5f69602b0c289965183f9ffbf2496": "{=awesome} vacation"

],

"desc": "In the phrase: \"Go on an {=awesome vacation}\"",

...,

],

0 => [

"hashToText" => [

"6bbb015218a9c99babf7213c1fa764d8": "awesome"

],

"desc": "In the phrase: \"Go on an {=awesome} vacation\"",

...,

]

],

"childParentMappings" => [

0 => 1,

1 => 2

]

}

Notice the description for "vacation" is auto-generated with an "In the phrase: ..." prefix. Additionally, we use a convention of adding an equal sign (=) prefix in the interpolation {=awesome vacation} to signal to the translator that this exact word or phrase goes in the associated outer sentence.

Furthermore, we provide a mapping [<childIndex> => <parentIndex>] in the collection output childParentMappings. At Meta, we use these to display all relevant inner and outer strings when translating any given piece of text. We recommend you do the same in whatever translation framework you use. Context is crucial for accurate translations.