x/rest/collection.go

205 lines
6.4 KiB
Go

package rest
import (
"fmt"
"net/http"
"reflect"
"strconv"
"strings"
jch_http "github.com/jchenry/jchenry/http"
)
const (
//IDPathParameter represents the entity's id in the parameter map IDPathParameter = "id"
IDPathParameter = "id"
)
// Collection - A Restful Collection interface backed by crud.CrudService
type CollectionInstance struct {
basePath string
name string
instanceType reflect.Type
service CollectionStore
}
type CollectionStore interface {
// Find returns a pointer to an array of the results found based on params
// or an error
Find(entityArrPtr interface{}, params map[string]interface{}) error
// Create returns the identifier for the newly accepted entity, or error
Create(entityPtr interface{}) error
// Update returns the id of the newly updated entity, or error
Update(entityPtr interface{}) error
// Delete returns whether the entity, specified by id, was successfully deleted
// or error
Delete(entityPtr interface{}) error
}
// type GetIDPathParameter func(*http.Request)
// Collection - Create a new instance of RESTCollection
func Collection(entityPtr interface{}, service CollectionStore) *CollectionInstance {
t := reflect.TypeOf(entityPtr).Elem()
return &CollectionInstance{
name: strings.ToLower(t.Name()),
instanceType: t,
service: service,
}
}
func (collection *CollectionInstance) Register(uriBase string, restServer *jch_http.Server) {
plural := properPlural(collection.name)
urlBase := uriBase + "/" + plural //collection.name + "s"
restServer.
POST(urlBase, "create a "+collection.name, http.HandlerFunc(collection.create)).
PUT(urlBase+"/:"+IDPathParameter, "update a "+collection.name, http.HandlerFunc(collection.update)).
DELETE(urlBase+"/:"+IDPathParameter, "delete a "+collection.name, http.HandlerFunc(collection.remove)).
GET(urlBase+"/:"+IDPathParameter, "get a "+collection.name+" by id", http.HandlerFunc(collection.find)).
GET(urlBase, "get "+collection.name+"s", http.HandlerFunc(collection.find))
}
func properPlural(word string) string {
if strings.HasSuffix(word, "s") {
return word
} else if strings.HasSuffix(word, "y") {
return word[:len(word)-1] + "ies"
} else {
return word + "s"
}
}
func (collection *CollectionInstance) create(response http.ResponseWriter, request *http.Request) {
entityPtr := reflect.New(collection.instanceType).Interface() //collection.instanceProviderPtr.NewInstance()
err := jch_http.ReadEntity(request, entityPtr)
if err != nil {
jch_http.WriteErrorResponse(response, http.StatusBadRequest, err.Error())
return
}
err = collection.service.Create(entityPtr)
if err != nil {
jch_http.WriteErrorResponse(response, http.StatusInternalServerError, err.Error())
return
}
response.WriteHeader(http.StatusCreated)
jch_http.WriteEntity(response, entityPtr)
}
func (collection *CollectionInstance) update(response http.ResponseWriter, request *http.Request) {
entityPtr := reflect.New(collection.instanceType).Interface() //collection.instanceProviderPtr.NewInstance()
err := jch_http.ReadEntity(request, entityPtr)
if err != nil {
jch_http.WriteErrorResponse(response, http.StatusBadRequest, err.Error())
return
}
id := request.Form.Get(IDPathParameter)
err = collection.service.Find(&[]interface{}{}, map[string]interface{}{IDPathParameter: id})
if err != nil {
if err == jch_http.ErrNotFound {
jch_http.WriteErrorResponse(response, http.StatusNotFound, fmt.Sprintf("%v with id %v not found", collection.name, id))
} else {
jch_http.WriteErrorResponse(response, http.StatusInternalServerError, err.Error())
}
return
}
err = collection.service.Update(entityPtr)
if err != nil {
jch_http.WriteErrorResponse(response, http.StatusInternalServerError, err.Error())
return
}
response.WriteHeader(http.StatusOK)
jch_http.WriteEntity(response, entityPtr)
}
func (collection *CollectionInstance) remove(response http.ResponseWriter, request *http.Request) {
id := request.Form.Get(IDPathParameter)
err := collection.service.Find(&[]interface{}{}, map[string]interface{}{IDPathParameter: id})
if err != nil {
if err == jch_http.ErrNotFound {
jch_http.WriteErrorResponse(response, http.StatusNotFound, fmt.Sprintf("%v with id %v not found", collection.name, id))
} else {
jch_http.WriteErrorResponse(response, http.StatusInternalServerError, err.Error())
}
return
}
entityPtr := reflect.New(collection.instanceType).Interface() //collection.instanceProviderPtr.NewInstance()
field := reflect.Indirect(reflect.ValueOf(entityPtr)).FieldByName(strings.ToUpper(IDPathParameter))
if !field.CanSet() {
jch_http.WriteErrorResponse(response, http.StatusInternalServerError, "entity does not have "+IDPathParameter+" field or field is not setable")
}
parsedID, err := strconv.ParseInt(id, 0, 64)
if err != nil {
jch_http.WriteErrorResponse(response, http.StatusInternalServerError, err.Error())
}
field.SetInt(parsedID)
err = collection.service.Delete(entityPtr)
if err != nil {
jch_http.WriteErrorResponse(response, http.StatusInternalServerError, err.Error())
return
}
response.WriteHeader(http.StatusNoContent)
}
func (collection *CollectionInstance) find(response http.ResponseWriter, request *http.Request) {
id := request.Form.Get(IDPathParameter)
arrv := reflect.New(reflect.SliceOf(reflect.PtrTo(collection.instanceType)))
arri := arrv.Interface()
err := collection.service.Find(arri, valuesToMap(request.URL.Query(), id))
if err != nil {
if err == jch_http.ErrNotFound {
jch_http.WriteErrorResponse(response, http.StatusNotFound, fmt.Sprintf("%v with id %v not found", collection.name, id))
} else {
jch_http.WriteErrorResponse(response, http.StatusInternalServerError, err.Error())
}
return
}
var results interface{}
if reflect.Indirect(arrv).Len() == 1 {
results = reflect.Indirect(arrv).Index(0).Interface()
fmt.Println(results)
} else {
results = &ResultSetResponse{
Metadata: Metadata{
ResultSet: ResultSetMetadata{
Count: reflect.Indirect(arrv).Len(),
//TODO: need to accomidate limit and offset here.
},
},
Results: arri,
}
}
response.WriteHeader(http.StatusOK)
jch_http.WriteEntity(response, results)
}
func valuesToMap(params map[string][]string, id string) map[string]interface{} {
m := make(map[string]interface{})
for key, val := range params {
if len(val) == 1 {
m[key] = val[0]
} else {
m[key] = val
}
}
if id != "" {
m[IDPathParameter] = id
}
return m
}