use enum for grades

Author: fabiotadashi

kotlin-ktor/src/main/java/com/baeldung/thymeleaf/data/DataHolder.kt

@@ -12,7 +12,7 @@ object DataHolder {
         findStudentById(studentId)
             .gradeList.forEach { grade ->
                 grade.apply {
-                    value = parameters[grade.id] ?: "F"
+                    gradeValue = parameters[grade.id]?.let { GradeValue.valueOf(it) }
                 }
             }
     }

kotlin-ktor/src/main/java/com/baeldung/thymeleaf/data/Grade.kt

@@ -3,5 +3,5 @@ package com.baeldung.thymeleaf.data
 data class Grade (
     val id: String,
     val subject: String,
-    var value: String = String()
+    var gradeValue: GradeValue? = GradeValue.EMPTY
 )

kotlin-ktor/src/main/java/com/baeldung/thymeleaf/data/GradeValue.kt

@@ -0,0 +1,20 @@
+package com.baeldung.thymeleaf.data
+
+enum class GradeValue(val displayValue: String) {
+
+    A("A"),
+    A_PLUS("A+"),
+    A_MINUS("A-"),
+    B("B"),
+    B_PLUS("B+"),
+    B_MINUS("B-"),
+    C("C"),
+    C_PLUS("C+"),
+    C_MINUS("C-"),
+    D("D"),
+    D_PLUS("D+"),
+    D_MINUS("D-"),
+    F("F"),
+    EMPTY("")
+
+}

kotlin-ktor/src/main/java/com/baeldung/thymeleaf/data/Student.kt

@@ -10,5 +10,5 @@ data class Student(
         get() = "$firstName $lastName"
 
     val hasAllGrades: Boolean
-        get() = gradeList.firstOrNull { grade -> grade.value.isBlank() } == null
+        get() = gradeList.firstOrNull { grade -> grade.gradeValue == GradeValue.EMPTY} == null
 }

kotlin-ktor/src/main/java/com/baeldung/thymeleaf/server/plugins/Routing.kt

@@ -1,6 +1,7 @@
 package com.baeldung.thymeleaf.server.plugins
 
 import com.baeldung.thymeleaf.data.DataHolder
+import com.baeldung.thymeleaf.data.GradeValue
 import io.ktor.server.application.*
 import io.ktor.server.request.*
 import io.ktor.server.response.*
@@ -13,7 +14,14 @@ fun Application.configureRouting() {
             call.respond(ThymeleafContent("index", mapOf("studentList" to DataHolder.getStudentList())))
         }
         get("/report-card/{id}") {
-            call.respond(ThymeleafContent("report-card", mapOf("student" to DataHolder.findStudentById(call.parameters["id"]))))
+            call.respond(
+                ThymeleafContent("report-card",
+                    mapOf(
+                        "student" to DataHolder.findStudentById(call.parameters["id"]),
+                        "gradeOptionList" to GradeValue.entries
+                    )
+                )
+            )
         }
         post("/report-card/{id}") {
             val parameters = call.receiveParameters()

kotlin-ktor/src/main/resources/templates/report-card.html

@@ -22,7 +22,14 @@ <h3>Name: <span th:text="${student.fullName}"/></h3>
             <tbody>
             <tr th:each="grade : ${student.gradeList}">
                 <td th:text="${grade.subject}"></td>
-                <td><input type="text" th:attr="value = ${grade.value}" th:name="${grade.id}"></td>
+                <td>
+                    <select th:name="${grade.id}">
+                        <option th:each="gradeOption : ${gradeOptionList}"
+                                th:value="${gradeOption}"
+                                th:text="${gradeOption.displayValue}"
+                                th:selected="${grade.gradeValue == gradeOption}"/>
+                    </select>
+                </td>
             </tr>
             </tbody>
         </table>

kotlin-ktor/src/test/java/com/baeldung/thymeleaf/data/DataHolderUnitTest.kt

@@ -39,10 +39,10 @@ class DataHolderUnitTest {
 
         val student = DataHolder.findStudentById("1")
         assertNotNull(student.gradeList)
-        assertEquals("A", student.gradeList.first { it.id == "1" }.value)
-        assertEquals("B", student.gradeList.first { it.id == "2" }.value)
-        assertEquals("C", student.gradeList.first { it.id == "3" }.value)
-        assertEquals("D", student.gradeList.first { it.id == "4" }.value)
+        assertEquals(GradeValue.A, student.gradeList.first { it.id == "1" }.gradeValue)
+        assertEquals(GradeValue.B, student.gradeList.first { it.id == "2" }.gradeValue)
+        assertEquals(GradeValue.C, student.gradeList.first { it.id == "3" }.gradeValue)
+        assertEquals(GradeValue.D, student.gradeList.first { it.id == "4" }.gradeValue)
     }
 
 }

kotlin-ktor/src/test/java/com/baeldung/thymeleaf/data/StudentUnitTest.kt

@@ -26,8 +26,8 @@ class StudentUnitTest {
             firstName = "John",
             lastName = "Doe",
             gradeList = listOf(
-                Grade(id = "1", subject = "Reading", value = "A"),
-                Grade(id = "2", subject = "Writing", value = "A"),
+                Grade(id = "1", subject = "Reading", gradeValue = GradeValue.A),
+                Grade(id = "2", subject = "Writing", gradeValue = GradeValue.A),
             )
         )
 
@@ -41,7 +41,7 @@ class StudentUnitTest {
             firstName = "John",
             lastName = "Doe",
             gradeList = listOf(
-                Grade(id = "1", subject = "Reading", value = "A"),
+                Grade(id = "1", subject = "Reading", gradeValue = GradeValue.A),
                 Grade(id = "2", subject = "Writing"),
             )
         )