typeful-fetch
v0.1.4
Published
Fetch Endpoints with Types
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Typeful Fetch
A fetch builder with type support
Usage
First, you'll need to define some Descriptors to describe your fetch endpoints. Then just call createClient
with your descriptors and you're good to go! See examples below.
See references for more details.
Examples
import {
createClient,
RouterDescriptor,
HandlerDescriptor
} from 'typeful-fetch'
type D = RouterDescriptor<{
'/': {
GET: HandlerDescriptor<{
querystring: {
aaa: string
}
response: {
200: {
bbb: string
}
}
}>
POST: HandlerDescriptor<{
body: {
ccc: string
}
response: {
200: {
ddd: string
}
}
}>
}
'/misc': RouterDescriptor<{
'/': {
PUT: HandlerDescriptor<{
body: {
eee: string
}
response: {
200: {
fff: string
}
}
}>
}
'/hello': {
GET: HandlerDescriptor<{
response: {
200: {
ggg: string
}
}
}>
}
}>
}>
const client = createClient<D>('http://localhost:3000/')
client.$get.query({ aaa: '123' }).fetch() // Promise<{ bbb: string; }>
client.$post.body({ ccc: '456' }).fetch() // Promise<{ ddd: string; }>
client.misc.$put.body({ eee: '789' }).fetch() // Promise<{ fff: string; }>
client.misc.hello.$get.fetch() // Promise<{ ggg: string; }>
More examples could be found in the unit tests.
References
Descriptors
Descriptors are used to describe your fetch endpoints. They are used to generate a client with type support.
We only have two types of descriptors: RouterDescriptor
and HandlerDescriptor
.
RouterDescriptor
type Route = RouterDescriptor<any> | Record<string, HandlerDescriptor<any>>
interface RouterDescriptor<Routes extends Record<string, Route>> {...}
RouterDescriptor is used to describe a router. It takes a generic type Routes
which is a record of routes. Each route can be either a RouterDescriptor
or a record of method to HandlerDescriptor
.
Also, route with a prefix /
will have that prefix removed. Thus, the following two descriptors are equivalent:
type D1 = RouterDescriptor<{
'/hello': {
GET: HandlerDescriptor<{ response: { 200: { a: string } } }>
}
}>
type D2 = RouterDescriptor<{
hello: {
GET: HandlerDescriptor<{ response: { 200: { a: string } } }>
}
}>
But we recommend using the first one, because it's more explicit.
Notice that we have special handling for the /
route. It is used to describe the root route of a router. If exists, it should be a record of method to HandlerDescriptor
. Otherwise, the type inference is not promised to succeed.
HandlerDescriptor
interface EndpointSchema<
Body,
Query,
Params,
Headers,
Response extends Record<number, any>
> {
body?: Body
querystring?: Query
params?: Params
headers?: Headers
response?: Response
}
interface HandlerDescriptor<Schema extends EndpointSchema<any, any, any, any, any>> {...}
HandlerDescriptor is used to describe a handler. Please notice that handlers have nothing to do with the path and method; they are just used to describe the schema of the endpoint.
To have the generated fetch
return a promise with the correct type, you need to specify the response
field in the schema. The key of the response
field should be the status code of the response, and the value should be the type of the response body. Thus, you should at least specify the response.200
field.
API
createClient
function createClient<R extends RouterDescriptor<any>>(
path: string,
options: RequestInit = {}
)
createClient
takes a RouterDescriptor
as generic parameter and returns a client with type support.
Parameters:
path
: the base path of the clientoptions
: the default options of the client, which'll be deep merged into every fetch request
Returns:
A client with type support, which have the intuitive structure corresponding to the given RouterDescriptor
.
Generally speaking, you will have to use client.some.path.to.the.api.$method
to get a ClientHandler
, using which you could form the actual fetch request. The expression given above will be mapped into an URL ${path}/some/path/to/the/api
and a method method
, which is saved in the ClientHandler
that you got.
Also, you could use client.$unsafe
to get a client with identical path and options, but have type checking turned off. Use this if you want to use the client to fetch endpoints that are not described by the RouterDescriptor
.
ClientHandler
Methods:
body
: set the body of the requestquery
: set the querystring of the requestparams
: set the params of the requestheaders
: set the headers of the requestfetch
: form and fire the actual fetch request
Notice that query
is serialized using the qs
package, and params
are implemented by simple doing string replacement stuff. Pay attention when using these two methods.
Please refer to the code for more details.