Added multipart reader

Author: djthorpe

pkg/httprequest/query.go

@@ -28,14 +28,9 @@ var (
 
 // Read the request query parameters into a structure
 func Query(q url.Values, v any) error {
-	rv := reflect.ValueOf(v)
-	if rv.Kind() != reflect.Ptr {
-		return errBadRequest.With("v must be a pointer")
-	} else {
-		rv = rv.Elem()
-	}
-	if rv.Kind() != reflect.Struct {
-		return errBadRequest.With("v must be a pointer to a struct")
+	rv, err := structValue(v)
+	if err != nil {
+		return err
 	}
 
 	// Enumerate fields
@@ -70,6 +65,22 @@ func Query(q url.Values, v any) error {
 	return nil
 }
 
+///////////////////////////////////////////////////////////////////////////////
+// PRIVATE METHODS
+
+func structValue(v any) (reflect.Value, error) {
+	rv := reflect.ValueOf(v)
+	if rv.Kind() != reflect.Ptr {
+		return reflect.ValueOf(nil), errBadRequest.With("v must be a pointer")
+	} else {
+		rv = rv.Elem()
+	}
+	if rv.Kind() != reflect.Struct {
+		return reflect.ValueOf(nil), errBadRequest.With("v must be a pointer to a struct")
+	}
+	return rv, nil
+}
+
 func jsonName(field reflect.StructField) string {
 	tag := field.Tag.Get(tagName)
 	if tag == "-" {
@@ -81,6 +92,30 @@ func jsonName(field reflect.StructField) string {
 	return field.Name
 }
 
+func writableFieldForName(v any, name string) (reflect.Value, error) {
+	rv, err := structValue(v)
+	if err != nil {
+		return reflect.ValueOf(nil), err
+	}
+
+	// Enumerate fields
+	for _, field := range reflect.VisibleFields(rv.Type()) {
+		tag := jsonName(field)
+		if tag == "" || tag != name {
+			continue
+		}
+
+		// Get the value - return success
+		v := rv.FieldByIndex(field.Index)
+		if v.CanSet() {
+			return v, nil
+		}
+	}
+
+	// Return failure
+	return reflect.ValueOf(nil), errBadRequest.With("field %q not found or not writable", name)
+}
+
 func setQueryValue(tag string, v reflect.Value, value []string) error {
 	// Set zero-value
 	if len(value) == 0 {

pkg/httprequest/read.go

@@ -5,12 +5,21 @@ import (
 	"errors"
 	"io"
 	"net/http"
+	"reflect"
 
 	// Packages
-	"github.com/mutablelogic/go-server/pkg/httpresponse"
+	gomultipart "github.com/mutablelogic/go-client/pkg/multipart"
+	httpresponse "github.com/mutablelogic/go-server/pkg/httpresponse"
 	types "github.com/mutablelogic/go-server/pkg/types"
 )
 
+///////////////////////////////////////////////////////////////////////////////
+// GLOBALS
+
+const (
+	FormDataMaxMemory = 256 << 20 // 256 MB
+)
+
 ///////////////////////////////////////////////////////////////////////////////
 // PUBLIC METHODS
 
@@ -28,6 +37,8 @@ func Read(r *http.Request, v interface{}) error {
 		return readJson(r, v)
 	case types.ContentTypeTextPlain:
 		return readString(r, v)
+	case types.ContentTypeFormData:
+		return readFormData(r, v)
 	}
 
 	// Cannot handle this content type
@@ -66,3 +77,48 @@ func readString(r *http.Request, v any) error {
 		return httpresponse.ErrInternalError.Withf("cannot read %T as string", v)
 	}
 }
+
+var (
+	typeFile = reflect.TypeOf(gomultipart.File{})
+)
+
+func readFormData(r *http.Request, v any) error {
+	if err := r.ParseMultipartForm(FormDataMaxMemory); err != nil {
+		return err
+	}
+	if r.MultipartForm == nil {
+		return httpresponse.ErrBadRequest.With("Missing form data")
+	}
+
+	// Set non-file fields
+	if err := Query(r.MultipartForm.Value, v); err != nil {
+		return err
+	}
+	// Set file fields - we only support one file per field
+	for key, values := range r.MultipartForm.File {
+		if len(values) == 0 {
+			continue
+		}
+		// Get the first file for the field
+		value, err := writableFieldForName(v, key)
+		if err != nil {
+			return err
+		}
+		switch value.Type() {
+		case typeFile:
+			body, err := values[0].Open()
+			if err != nil {
+				return errBadRequest.Withf("cannot open file %q: %v", values[0].Filename, err)
+			}
+			value.Set(reflect.ValueOf(gomultipart.File{
+				Path: values[0].Filename,
+				Body: body,
+			}))
+		default:
+			return httpresponse.ErrBadRequest.Withf("cannot set field %q of type %s", key, value.Type())
+		}
+	}
+
+	// Return success
+	return nil
+}