339 lines
13 KiB
Markdown
339 lines
13 KiB
Markdown
<p align="center">
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<a href="https://github.com/xdrm-io/aicra">
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<img src="https://github.com/xdrm-io/aicra/raw/0.4.0/readme.assets/logo.png" alt="aicra logo" width="200" height="200">
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</a>
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</p>
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<h3 align="center">aicra</h3>
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<p align="center">
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Fast, intuitive, and powerful configuration-driven engine for faster and easier <em>REST</em> development.
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</p>
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[](https://opensource.org/licenses/MIT)
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[](https://golang.org/doc/go1.16)
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[](https://pkg.go.dev/github.com/xdrm-io/aicra)
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[](https://goreportcard.com/report/github.com/xdrm-io/aicra)
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## Presentation
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`aicra` is a lightweight and idiomatic configuration-driven engine for building REST services. It's especially good at helping you write large APIs that remain maintainable as your project grows.
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The focus of the project is to allow you to build a fully-featured REST API in an elegant, comfortable and inexpensive way. This is achieved by using a single configuration file to drive the server. This one file describes your entire API: methods, uris, input data, expected output, permissions, etc.
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Repetitive tasks are automatically processed by `aicra` based on your configuration, you're left with implementing your handlers (_usually business logic_).
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## Table of contents
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<!-- toc -->
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- [Installation](#installation)
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- [What's automated](#whats-automated)
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- [Getting started](#getting-started)
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- [Configuration file](#configuration-file)
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* [Services](#services)
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* [Input and output parameters](#input-and-output-parameters)
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* [Example](#example)
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- [Writing your code](#writing-your-code)
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- [Changelog](#changelog)
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<!-- tocstop -->
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## Installation
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To install the aicra package, you need to install Go and set your Go workspace first.
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> not tested under Go 1.14
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1. you can use the below Go command to install aicra.
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```bash
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$ go get -u github.com/xdrm-io/aicra
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```
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2. Import it in your code:
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```go
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import "github.com/xdrm-io/aicra"
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```
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## What's automated
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As the configuration file is here to make your life easier, let's take a quick look at what you do not have to do ; or in other words, what does `aicra` automates.
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Http requests are only accepted when they have the permissions you have defined. If unauthorized, the request is rejected with an error response.
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Request data is automatically extracted and validated before it reaches your code. If a request has missing or invalid data an automatic error response is sent.
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When launching the server, it ensures everything is ok and won't start until fixed. You will get errors for:
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- handler signature does not match the configuration
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- a configuration service has no handler
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- a handler does not match any service
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The same applies if your configuration is invalid:
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- unknown HTTP method
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- invalid uri
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- uri collision between 2 services
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- missing fields
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- unknown data type
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- input name collision
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## Getting started
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Here is the minimal code to launch your aicra server assuming your configuration file is `api.json`.
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```go
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package main
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import (
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"log"
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"net/http"
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"os"
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"github.com/xdrm-io/aicra"
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"github.com/xdrm-io/aicra/api"
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"github.com/xdrm-io/aicra/datatype/builtin"
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)
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func main() {
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builder := &aicra.Builder{}
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// register data validators
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builder.AddType(builtin.BoolDataType{})
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builder.AddType(builtin.UintDataType{})
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builder.AddType(builtin.StringDataType{})
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// load your configuration
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config, err := os.Open("api.json")
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if err != nil {
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log.Fatalf("cannot open config: %s", err)
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}
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err = builder.Setup(config)
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config.Close() // free config file
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if err != nil {
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log.Fatalf("invalid config: %s", err)
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}
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// add http middlewares (logger)
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builder.With(func(next http.Handler) http.Handler{ /* ... */ })
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// add contextual middlewares (authentication)
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builder.WithContext(func(next http.Handler) http.Handler{ /* ... */ })
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// bind handlers
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err = builder.Bind(http.MethodGet, "/user/{id}", getUserById)
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if err != nil {
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log.Fatalf("cannog bind GET /user/{id}: %s", err)
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}
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// build your services
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handler, err := builder.Build()
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if err != nil {
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log.Fatalf("cannot build handler: %s", err)
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}
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http.ListenAndServe("localhost:8080", handler)
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}
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```
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If you want to use HTTPS, you can configure your own `http.Server`.
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```go
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func main() {
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server := &http.Server{
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Addr: "localhost:8080",
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TLSConfig: tls.Config{},
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// ...
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Handler: AICRAHandler,
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}
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server.ListenAndServe()
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}
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```
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## Configuration file
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First of all, the configuration uses `json`.
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> Quick note if you thought: "I hate JSON, I would have preferred yaml, or even xml !"
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>
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> I've had a hard time deciding and testing different formats including yaml and xml.
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> But as it describes our entire api and is crucial for our server to keep working over updates; xml would have been too verbose with growth and yaml on the other side would have been too difficult to read. Json sits in the right spot for this.
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Let's take a quick look at the configuration format !
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> if you don't like boring explanations and prefer a working example, see [here](https://git.xdrm.io/go/articles-api/src/master/api.json)
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### Services
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To begin with, the configuration file defines a list of services. Each one is defined by:
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- `method` an HTTP method
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- `path` an uri pattern (can contain variables)
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- `info` a short description of what it does
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- `scope` a list of the required permissions
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- `in` a list of input arguments
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- `out` a list of output arguments
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```json
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[
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{
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"method": "GET",
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"path": "/article",
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"scope": [["author", "reader"], ["admin"]],
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"info": "returns all available articles",
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"in": {},
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"out": {}
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}
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]
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```
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The `scope` is a 2-dimensional list of permissions. The first list means **or**, the second means **and**, it allows for complex permission combinations. The example above can be translated to: this method requires users to have permissions (author **and** reader) **or** (admin)
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### Input and output parameters
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Input and output parameters share the same format, featuring:
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- `info` a short description of what it is
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- `type` its data type (_c.f. validation_)
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- `?` whether it is mandatory or optional
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- `name` a custom name for easy access in code
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```json
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[
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{
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"method": "PUT",
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"path": "/article/{id}",
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"scope": [["author"]],
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"info": "updates an article",
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"in": {
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"{id}": { "info": "...", "type": "int", "name": "id" },
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"GET@title": { "info": "...", "type": "?string", "name": "title" },
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"content": { "info": "...", "type": "string" }
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},
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"out": {
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"title": { "info": "updated article title", "type": "string" },
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"content": { "info": "updated article content", "type": "string" }
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}
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}
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]
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```
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If a parameter is optional you just have to prefix its type with a question mark, by default all parameters are mandatory.
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The format of the key of input arguments defines where it comes from:
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1. `{param}` is an URI parameter that is extracted from the `"path"`
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2. `GET@param` is an URL parameter that is extracted from the [HTTP Query](https://tools.ietf.org/html/rfc3986#section-3.4) syntax.
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3. `param` is a body parameter that can be extracted from 3 formats independently:
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- _url encoded_: data send in the body following the [HTTP Query](https://tools.ietf.org/html/rfc3986#section-3.4) syntax.
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- _multipart_: data send in the body with a dedicated [format](https://tools.ietf.org/html/rfc2388#section-3). This format can be quite heavy but allows to transmit data as well as files.
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- _JSON_: data sent in the body as a json object ; The _Content-Type_ header must be `application/json` for it to work.
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### Example
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```json
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[
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{
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"method": "PUT",
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"path": "/article/{id}",
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"scope": [["author"]],
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"info": "updates an article",
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"in": {
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"{id}": { "info": "...", "type": "int", "name": "id" },
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"GET@title": { "info": "...", "type": "?string", "name": "title" },
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"content": { "info": "...", "type": "string" }
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},
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"out": {
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"id": { "info": "updated article id", "type": "uint" },
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"title": { "info": "updated article title", "type": "string" },
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"content": { "info": "updated article content", "type": "string" }
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}
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}
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]
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```
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1. `{id}` is extracted from the end of the URI and is a number compliant with the `int` type checker. It is renamed `ID`, this new name will be sent to the handler.
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2. `GET@title` is extracted from the query (_e.g. [http://host/uri?get-var=value](http://host/uri?get-var=value)_). It must be a valid `string` or not given at all (the `?` at the beginning of the type tells that the argument is **optional**) ; it will be named `title`.
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3. `content` can be extracted from json, multipart or url-encoded data; it makes no difference and only give clients a choice over the technology to use. If not renamed, the variable will be given to the handler with its original name `content`.
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## Writing your code
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Besides your main package where you launch your server, you will need to create handlers matching services from the configuration.
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The code below implements a simple handler.
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```go
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// "in": {
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// "Input1": { "info": "...", "type": "int" },
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// "Input2": { "info": "...", "type": "?string" }
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// },
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type req struct{
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Input1 int
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Input2 *string // optional are pointers
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}
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// "out": {
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// "Output1": { "info": "...", "type": "string" },
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// "Output2": { "info": "...", "type": "bool" }
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// }
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type res struct{
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Output1 string
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Output2 bool
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}
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func myHandler(ctx context.Context, r req) (*res, api.Err) {
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err := doSomething()
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if err != nil {
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return nil, api.ErrFailure
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}
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return &res{"out1", true}, api.ErrSuccess
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}
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```
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If your handler signature does not match the configuration exactly, the server will print out the error and won't start.
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The `api.Err` type automatically maps to HTTP status codes and error descriptions that will be sent to the client as json; clients have to manage the same format for every response.
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```json
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{
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"error": {
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"code": 0,
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"reason": "all right"
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}
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}
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```
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## Changelog
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- [x] human-readable json configuration
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- [x] nested routes (*i.e. `/user/{id}` and `/user/post/{id}`*)
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- [x] nested URL arguments (*i.e. `/user/{id}` and `/user/{uid}/post/{id}`*)
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- [x] useful http methods: GET, POST, PUT, DELETE
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- [ ] add support for PATCH method
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- [ ] add support for OPTIONS method
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- [ ] it might be interesting to generate the list of allowed methods from the configuration
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- [ ] add CORS support
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- [x] manage request data extraction:
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- [x] URL slash-separated strings
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- [x] HTTP Query named parameters
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- [x] manage array format
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- [x] body parameters
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- [x] multipart/form-data (variables and file uploads)
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- [x] application/x-www-form-urlencoded
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- [x] application/json
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- [x] required vs. optional parameters with a default value
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- [x] parameter renaming
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- [x] generic type check (*i.e. you can add custom types alongside built-in ones*)
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- [x] built-in types
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- [x] `any` - matches any value
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- [x] `int` - see go types
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- [x] `uint` - see go types
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- [x] `float` - see go types
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- [x] `string` - any text
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- [x] `string(len)` - any string with a length of exactly `len` characters
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- [x] `string(min, max)` - any string with a length between `min` and `max`
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- [ ] `[]a` - array containing **only** elements matching `a` type
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- [ ] `a[b]` - map containing **only** keys of type `a` and values of type `b` (*a or b can be ommited*)
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- [x] generic handler implementation
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- [x] response interface
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- [x] generic errors that automatically formats into response
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- [x] builtin errors
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- [x] possibility to add custom errors
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- [x] check for missing handlers when building the handler
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- [x] check handlers not matching a route in the configuration at server boot
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- [x] specific configuration format errors qt server boot
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- [x] statically typed handlers - avoids having to check every input and its type (_which is used by context.Context for instance_)
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- [x] using reflection to use structs as input and output arguments to match the configuration
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- [x] check for input and output arguments structs at server boot
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- [x] check for unavailable types in configuration at server boot
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- [x] recover panics from handlers
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- [ ] improve tests and coverage
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