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https://github.com/bobg/mid
Middleware for HTTP services in Go
https://github.com/bobg/mid
Last synced: about 1 month ago
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Middleware for HTTP services in Go
- Host: GitHub
- URL: https://github.com/bobg/mid
- Owner: bobg
- License: mit
- Created: 2020-07-13T14:53:59.000Z (over 4 years ago)
- Default Branch: master
- Last Pushed: 2022-06-28T13:51:49.000Z (over 2 years ago)
- Last Synced: 2024-06-19T18:08:00.356Z (6 months ago)
- Language: Go
- Size: 41 KB
- Stars: 7
- Watchers: 2
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: Readme.md
- License: LICENSE
Awesome Lists containing this project
- awesome-go-extra - mid - 07-13T14:53:59Z|2022-06-28T13:51:49Z| (Web Frameworks / Fail injection)
README
# Mid - Assorted middleware for HTTP services.
[](https://pkg.go.dev/github.com/bobg/mid)
[](https://goreportcard.com/report/github.com/bobg/mid)
[](https://github.com/bobg/mid/actions/workflows/go.yml)
[](https://coveralls.io/github/bobg/mid?branch=master)
This is mid,
a collection of useful middleware for HTTP services.
## Err
The `Err` function turns a `func(http.ResponseWriter, *http.Request) error`
into an `http.Handler`,
allowing handler functions to return errors in a more natural fashion.
These errors result in the handler producing an HTTP 500 status code,
but `CodeErr` and `Responder` allow you to control this behavior
(see below).
A `nil` return produces a `200`,
or a `204` (“no content”) if no bytes were written to the response object.
Usage:
```go
func main() {
http.Handle("/foo", Err(fooHandler))
http.ListenAndServe(":8080", nil)
}
func fooHandler(w http.ResponseWriter, req *http.Request) error {
if x := req.FormValue("x"); x != "secret password" {
return CodeErr{C: http.StatusUnauthorized}
}
fmt.Fprintf(w, "You know the secret password")
return nil
}
```
## JSON
The `JSON` function turns a `func(context.Context, X) (Y, error)`
into an `http.Handler`,
where `X` is the type of a parameter into which the HTTP request body is automatically JSON-unmarshaled,
and `Y` is the type of a result that is automatically JSON-marshaled into the HTTP response.
Any error is handled as with `Err`
(see above).
All parts of the `func` signature are optional:
the `context.Context` parameter,
the `X` parameter,
the `Y` result,
and the `error` result.
Usage:
```go
func main() {
// Parses the request body as a JSON-encoded array of strings,
// then sorts, re-encodes, and returns that array.
http.Handle("/bar", JSON(barHandler))
http.ListenAndServe(":8080", nil)
}
func barHandler(inp []string) []string {
sort.Strings(inp)
return inp
}
```
## CodeErr and Responder
`CodeErr` is an `error` type suitable for returning from `Err`- and `JSON`-wrapped handlers that can control the HTTP status code that gets returned.
It contains an HTTP status code field and a nested `error`.
`Responder` is an interface
(implemented by `CodeErr`)
that allows an error type to control how `Err`- and `JSON`-wrapped handlers respond to the pending request.
## ResponseWrapper
`ResponseWrapper` is an `http.ResponseWriter` that wraps a nested `http.ResponseWriter` and also records the status code and number of bytes sent in the response.
## Trace
The `Trace` function wraps an `http.Handler` and decorates the `context.Context` in its `*http.Request` with any “trace ID” string found in the request header.
## Log
The `Log` function wraps an `http.Handler` with a function that writes a simple log line on the way into and out of the handler.
The log line includes any “trace ID” found in the request’s `context.Context`.