Rust support in Shopify Functions

You can write your functions in Rust. This guide describes the Rust crate that Shopify provides to help developers build with Shopify Functions.

Requirements

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You need to have graphql_client installed as a dependency in your project:

How it works

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Rust crate bundles graphql_client-based type generation, reduces boilerplate code, and makes it easier to unit testing various function inputs. Rust crate includes the following components:

Component	Description
`generate_types`	A macro that enables you to do the following: Generate structs based on your input query. Generate output and response types for the current Function API, based on the provided schema. Automatically generate an `.output.graphql` file for code generation purposes. You can add this file to your `.gitignore` file.
`shopify_function`	An attribute macro that marks the following function as the entry point for a function. It manages the function's `STDIN` input parsing and `STDOUT` output serialization for you.
`run_function_with_input`	A utility for unit testing that enables you to add new tests based on a given JSON input string.

Example implementation

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Explore an example implementation of Shopify Function Rust crate.

Shopify Rust function example

Explore an example of how to use the Shopify Function Rust crate to write a function.

Update an existing function

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You can update an existing function written in Rust to use the shopify_function attribute:

In your project, run cargo add shopify_function.
Run cargo add graphql_client@0.12.0.
Delete src/api.rs.

In main.rs, complete the following steps:

Add imports for shopify_function:
Remove references to mod api.
Add type generation directly under your imports:
Remove the main function entirely.
Attribute the function function with the shopify_function macro, and change its return type:

Update the types and fields utilized in the function to the new, auto-generated structs. The following table provides an example:

Old	New
`input::Input`	`input::ResponseData`
`input::Metafield`	`input::InputDiscountNodeMetafield`
`input::DiscountNode`	`input::InputDiscountNode`
`FunctionResult`	`output::FunctionResult`
`DiscountApplicationStrategy::First`	`output::DiscountApplicationStrategy::FIRST`

Add .output.graphql to your .gitignore file.

Next steps

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Explore the reference documentation for crate shopify_function.