Remove some duplication in API handlers

api/application.go

@@ -36,6 +36,20 @@ func (h *ApplicationHandler) applicationExists(token string) bool {
 	return application != nil
 }
 
+func (h *ApplicationHandler) getApplication(ctx *gin.Context) (*model.Application, error) {
+	id, err := getID(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	application, err := h.DB.GetApplicationByID(id)
+	if success := successOrAbort(ctx, http.StatusNotFound, err); !success {
+		return nil, err
+	}
+
+	return application, nil
+}
+
 // CreateApplication creates an application.
 func (h *ApplicationHandler) CreateApplication(ctx *gin.Context) {
 	var createApplication model.CreateApplication
@@ -69,16 +83,11 @@ func (h *ApplicationHandler) CreateApplication(ctx *gin.Context) {
 
 // DeleteApplication deletes an application with a certain ID.
 func (h *ApplicationHandler) DeleteApplication(ctx *gin.Context) {
-	id, err := getID(ctx)
+	application, err := h.getApplication(ctx)
 	if err != nil {
 		return
 	}
 
-	application, err := h.DB.GetApplicationByID(id)
-	if success := successOrAbort(ctx, http.StatusNotFound, err); !success {
-		return
-	}
-
 	if !isCurrentUser(ctx, application.UserID) {
 		return
 	}
@@ -98,22 +107,16 @@ func (h *ApplicationHandler) DeleteApplication(ctx *gin.Context) {
 
 // UpdateApplication updates an application with a certain ID.
 func (h *ApplicationHandler) UpdateApplication(ctx *gin.Context) {
-	id, err := getID(ctx)
+	application, err := h.getApplication(ctx)
 	if err != nil {
 		return
 	}
 
-	application, err := h.DB.GetApplicationByID(id)
-	if success := successOrAbort(ctx, http.StatusNotFound, err); !success {
-		return
-	}
-
 	if !isCurrentUser(ctx, application.UserID) {
 		return
 	}
 
 	var updateApplication model.UpdateApplication
-
 	if err := ctx.BindUri(&updateApplication); err != nil {
 		return
 	}

api/context.go

@@ -0,0 +1,19 @@
+package api
+
+import (
+	"errors"
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+)
+
+func getID(ctx *gin.Context) (uint, error) {
+	id, ok := ctx.MustGet("user").(uint)
+	if !ok {
+		err := errors.New("an error occured while retrieving ID from context")
+		ctx.AbortWithError(http.StatusInternalServerError, err)
+		return 0, err
+	}
+
+	return id, nil
+}

api/middleware.go

@@ -1,9 +1,6 @@
 package api
 
 import (
-	"errors"
-	"net/http"
-
 	"github.com/gin-gonic/gin"
 )
 
@@ -23,14 +20,3 @@ func RequireIDInURI() gin.HandlerFunc {
 		ctx.Set("id", requestModel.ID)
 	}
 }
-
-func getID(ctx *gin.Context) (uint, error) {
-	id, ok := ctx.MustGet("user").(uint)
-	if !ok {
-		err := errors.New("an error occured while retrieving ID from context")
-		ctx.AbortWithError(http.StatusInternalServerError, err)
-		return 0, err
-	}
-
-	return id, nil
-}

api/user.go

@@ -44,31 +44,48 @@ func (h *UserHandler) userExists(name string) bool {
 	return user != nil
 }
 
-func (h *UserHandler) ensureIsNotLastAdmin(ctx *gin.Context) (int, error) {
+func (h *UserHandler) requireMultipleAdmins(ctx *gin.Context) error {
 	if count, err := h.DB.AdminUserCount(); err != nil {
-		return http.StatusInternalServerError, err
+		ctx.AbortWithError(http.StatusInternalServerError, err)
+		return err
 	} else if count == 1 {
-		return http.StatusBadRequest, errors.New("instance needs at least one privileged user")
+		err := errors.New("instance needs at least one privileged user")
+		ctx.AbortWithError(http.StatusBadRequest, err)
+		return err
 	}
 
-	return 0, nil
+	return nil
+}
+
+func (h *UserHandler) getUser(ctx *gin.Context) (*model.User, error) {
+	id, err := getID(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	application, err := h.DB.GetUserByID(id)
+	if success := successOrAbort(ctx, http.StatusNotFound, err); !success {
+		return nil, err
+	}
+
+	return application, nil
 }
 
 // CreateUser creates a new user.
 // This method assumes that the requesting user has privileges.
 func (h *UserHandler) CreateUser(ctx *gin.Context) {
-	var externalUser model.CreateUser
+	var createUser model.CreateUser
 
-	if err := ctx.Bind(&externalUser); err != nil {
+	if err := ctx.Bind(&createUser); err != nil {
 		return
 	}
 
-	if h.userExists(externalUser.Name) {
+	if h.userExists(createUser.Name) {
 		ctx.AbortWithError(http.StatusBadRequest, errors.New("username already exists"))
 		return
 	}
 
-	user, err := h.DB.CreateUser(externalUser)
+	user, err := h.DB.CreateUser(createUser)
 
 	if success := successOrAbort(ctx, http.StatusInternalServerError, err); !success {
 		return
@@ -81,20 +98,14 @@ func (h *UserHandler) CreateUser(ctx *gin.Context) {
 //
 // This method assumes that the requesting user has privileges.
 func (h *UserHandler) DeleteUser(ctx *gin.Context) {
-	id, err := getID(ctx)
+	user, err := h.getUser(ctx)
 	if err != nil {
 		return
 	}
 
-	user, err := h.DB.GetUserByID(id)
-	if success := successOrAbort(ctx, http.StatusNotFound, err); !success {
-		return
-	}
-
 	// Last privileged user must not be deleted.
 	if user.IsAdmin {
-		if status, err := h.ensureIsNotLastAdmin(ctx); err != nil {
+		if err := h.requireMultipleAdmins(ctx); err != nil {
-			ctx.AbortWithError(status, err)
 			return
 		}
 	}
@@ -124,18 +135,12 @@ func (h *UserHandler) DeleteUser(ctx *gin.Context) {
 // This method assumes that the requesting user has privileges. If users can later update their own user, make sure they
 // cannot give themselves privileges.
 func (h *UserHandler) UpdateUser(ctx *gin.Context) {
-	id, err := getID(ctx)
+	user, err := h.getUser(ctx)
 	if err != nil {
 		return
 	}
 
-	user, err := h.DB.GetUserByID(id)
-	if success := successOrAbort(ctx, http.StatusNotFound, err); !success {
-		return
-	}
-
 	var updateUser model.UpdateUser
-
 	if err := ctx.BindUri(&updateUser); err != nil {
 		return
 	}
@@ -144,8 +149,7 @@ func (h *UserHandler) UpdateUser(ctx *gin.Context) {
 
 	// Last privileged user must not be taken privileges. Assumes that the current user has privileges.
 	if user.ID == currentUser.ID && !updateUser.IsAdmin {
-		if status, err := h.ensureIsNotLastAdmin(ctx); err != nil {
+		if err := h.requireMultipleAdmins(ctx); err != nil {
-			ctx.AbortWithError(status, err)
 			return
 		}
 	}

database/user.go

@@ -10,8 +10,8 @@ import (
 )
 
 // CreateUser creates a user.
-func (d *Database) CreateUser(externalUser model.CreateUser) (*model.User, error) {
+func (d *Database) CreateUser(createUser model.CreateUser) (*model.User, error) {
-	user := externalUser.IntoInternalUser(d.credentialsManager)
+	user := createUser.IntoInternalUser(d.credentialsManager)
 
 	return user, d.gormdb.Create(user).Error
 }