Go

This backend introduces support for routes written in Golang.

Install

npm install @primate/go

In addition, your system needs to have the go executable in its path, as it is used to compile the Go routes into Wasm.

Configure

Import and initialize the module in your configuration.

import go from "@primate/go";

export default {
  modules: [
    go(),
  ],
};

Use

Plain text

JavaScript documentation

Strings are served with the content type text/plain.

func Get(request Request) any {
  return "Donald";
}

This route function handles GET requests to the path /plain-text by serving them the string "Donald" in plain text.

JSON

JavaScript documentation

Maps (including arrays) are served with the content type application/json.

func Get(request Request) any {
  return []any{
    map[string]any{ "name": "Donald" },
    map[string]any{ "name": "Ryan" },
  };
}

This route function handles GET requests to the path /json by serving them a JSON array.

For your convenience, Primate furnishes you with two types, Object which is map[string]any and Array which is []any, allowing you to write the route more elegantly.

func Get(request Request) any {
  return Array{
    Object{ "name": "Donald" },
    Object{ "name": "Ryan" },
  };
}

Redirect

JavaScript documentation

The Redirect handler allows you to redirect responses.

import "github.com/primatejs/go/primate"

func Get(request Request) any {
  return primate.Redirect("https://primatejs.com");
}

To use a different redirect status, use the second parameter as a map with a status field.

import "github.com/primatejs/go/primate"

func Get(request Request) any {
  // moved permanently
  return primate.Redirect("https://primatejs.com", Object{ "status": 301 });
}

View

JavaScript documentation

The View handler allows you to serve responses with content type text/html from the components directory.

import "github.com/primatejs/go/primate"

func Get(request Request) any {
  return primate.View("hello.html");
}

In this case, Primate will load the HTML component at components/hello.html, inject the HTML component code into the index file located at pages/app.html and serve the resulting file at the path GET /html. In case no such file exists, Primate will fall back to its default app.html.

<p>Hello, world!</p>

If you're using any of the supported frontends, you can also pass props directly to the frontend component.

First, create the frontend component, in this case Svelte.

<script>
  export let posts;
</script>
<h1>All posts</h1>
{#each posts as { id, title }}
<h2><a href="/post/{id}">{title}</a></h2>
{/each}
<style>
  button {
    border-radius: 4px;
    background-color: #5ca1e1;
    border: none;
    color: #fff;
    display: block;
  }
</style>

Then create the route, and pass props to the component.

import "github.com/primatejs/go/primate"

func Get(request Request) any {
  posts := Array{Object{
    "id": 1,
    "title": "First post",
  }};

  return primate.View("PostIndex.svelte", Object{ "posts": posts });
}

Your rendered route with a Svelte component will be accessible at http://localhost:6161/svelte.

The request object

Route verb functions accept a single parameter representing request data. This aggregate object allows easy access to the request Body, any Path parameters defined with braces, the Query string split into parts, Cookies as well as other Headers.

Body

JavaScript documentation

The request body.

func Post(request Request) any {
  return "Hello, " + request.Body["name"].(string);
}

If a client sends a POST request to /your-name using the content type application/json and {"name": "Donald"} as body, this route will respond with 200 saying Hello, Donald.

Path, Query, Cookies, Headers

JavaScript documentation

As in JavaScript, these properties work as dispatchers, providing a Get function to access individual properties. In addition, any types defined in types will be available to the dispatcher. The Dispatcher struct is defined as follows.

type Dispatcher struct {
  Get func(string) any
  // dynamic runtime type getters
}

In addition, any types defined in types will be available to a Dispatcher.

Suppose you have defined the following type.

import is from "@rcompat/invariant/is";

const valid = /^[^\W_]{8}-[^\W_]{4}-[^\W_]{4}-[^\W_]{4}-[^\W_]{12}$/u;

export default {
  base: "string",
  validate(value) {
    // make sure value is a string, otherwise throw
    is(value).string();

    if (valid.test(value)) {
      return value;
    }
    throw new Error(`${value} is not a valid UUID`);
  },
};

The Dispatcher struct would now look a little different.

type Dispatcher struct {
  Get func(string) any
  GetUuid func(string) (string, error)
}

In Javascript, calling request.query.getUuid("id") can throw. In Go, request.Query.GetUuid("id") returns a non-nil error in case the type's validate function threw.

Session

JavaScript documentation

If the @primate/session module is active, the Request object passed to a route will contain an additional Session property, allowing you to retrieve and set session data from within Go.

A Session struct is as defined as follows.

type Session struct {
  Exists func() bool
  Get func(string) any
  Set func(string, any) error
  Create func(map[string]any)
  Destroy func()
}

Here is a Go route that, in case a session does not exist, creates it with a count equaling 0 and otherwise increments count by 1. In both cases, the session data is served to the client as JSON.

func Get(request Request) any {
  if (!request.Session.Exists()) {
    request.Session.Create(Object{"count": 0});
  } else {
    count := request.Session.Get("count").(float64);
    request.Session.Set("count", count + 1);
  }

  return Object{ "count": request.Session.Get("count") };
}

Configuration options

extension

Default ".go"

The file extension associated with Go routes.

Resources

• Repository
• Error list