Custom Fields

If you've got a custom scalar, or just want to convert e.g. an integer to a string to properly fit a record type (see above), you can use the @ppxCustom directive to insert a custom function in the decoder:

module StringHeight = {

type t = string;

let parse = (height) => string_of_float(height);

let serialize = (height) => float_of_string(height);

}

module HeroQuery = [%graphql {|

{

hero {

name

height @ppxCustom(module: "StringHeight")

mass

}

}

|}];

In this example, height will be converted from a float to a string in the result. Using the module argument, you can specify any decoder module with the functions parse, serialize and type t.

If you have custom scalars that you'd always would like to conver to a specific type. You can do that in the customFields part of the bsconfig.json configuration.