front side validations

src/components/courses/ManageCoursePage.js

@@ -38,8 +38,22 @@ function ManageCoursePage({ courses, authors, actions, history, ...props }) {
     }));
   }
 
+  function formIsValid() {
+    const { title, authorId, category } = course;
+    const errors = {};
+
+    if (!title) errors.title = "Title is required.";
+    if (!authorId) errors.author = "Author is required";
+    if (!category) errors.category = "Category is required";
+
+    setErrors(errors);
+    // Form is valid if the errors object still has no properties
+    return Object.keys(errors).length === 0;
+  }
+
   function handleSave(event) {
     event.preventDefault();
+    if (!formIsValid()) return;
     setSaving(true);
     actions
       .saveCourse(course)