params.go

package hyperdrive

import (
	"fmt"
	"net/http"
	"net/url"

	"github.com/gorilla/mux"
)

// QueryParams extracts the values from the request QueryString. It returns
// a url.Values object (essentially map[string][]string). If the
// request method is not GET, an empty url.Values is returned.
func QueryParams(r *http.Request) url.Values {
	if r.Method == "GET" {
		r.ParseForm()
		return r.Form
	}
	return url.Values{}
}

// BodyParams deserializes the input, and extracts the values from the request
// body. It returns a url.Values object (essentially map[string][]string). If
// the request method is GET, an empty url.Values is returned.
func BodyParams(r *http.Request) url.Values {
	if r.Method != "GET" {
		return url.Values{}
	}
	return url.Values{}
}

// PathParams extracts the values from the request path which match named
// params in the route. They are returned as url.Values for consistincey
// with http.Request.Form's behaviour.
func PathParams(r *http.Request) url.Values {
	var params = url.Values{}
	for k, v := range mux.Vars(r) {
		params.Add(k, v)
	}
	return params
}

// Params extracts the param values from all sources: query, body, and path -- in
// that order. Each subsequent source will overwrite values with the same key, to
// ensure API client intent is maintained in a consistent way.
func Params(r *http.Request) url.Values {
	var params = QueryParams(r)

	for k, values := range BodyParams(r) {
		for _, v := range values {
			params.Set(k, v)
		}
	}

	for k, v := range mux.Vars(r) {
		params.Set(k, v)
	}

	return params
}

// GetParams returns all allowed request params. It returns an error on
// the first required param is not present. GetParams is intended to be used
// in your method handlers in a given endpoint.
func GetParams(e Endpointer, r *http.Request) (url.Values, error) {
	pp := parseEndpoint(e)
	p := Params(r)
	for k := range p {
		if contains(pp.Allowed(r.Method), k) != true {
			p.Del(k)
		}
	}

	for _, required := range pp.Required(r.Method) {
		if k, ok := p[required]; !ok {
			return p, fmt.Errorf("Missing required parameter: %s", k)
		}
	}
	return p, nil
}

// Parameter is an interface to allow users to create self-describing custom types
// to be used as endpoint params. The name and description are reusable
// across multiple endpoints.
type Parameter interface {
	GetName() string
	GetDesc() string
}