3.3: using mapped types.

.idea/workspace.xml

@@ -2,9 +2,6 @@
 <project version="4">
   <component name="ChangeListManager">
     <list default="true" id="c6f02f4e-af06-43d1-8bc0-507af01d0573" name="Default Changelist" comment="">
-      <change afterPath="$PROJECT_DIR$/.idea/codeStyles/Project.xml" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/.idea/codeStyles/codeStyleConfig.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/codeStyles/codeStyleConfig.xml" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/.idea/workspace.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/workspace.xml" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/course/src/app/services/reportItem.service.ts" beforeDir="false" afterPath="$PROJECT_DIR$/course/src/app/services/reportItem.service.ts" afterDir="false" />
     </list>
     <option name="EXCLUDED_CONVERTED_TO_IGNORED" value="true" />
@@ -30,7 +27,7 @@
           <entry key="gitignore" value="2" />
           <entry key="groovy" value="1" />
           <entry key="json" value="16" />
-          <entry key="ts" value="29" />
+          <entry key="ts" value="33" />
           <entry key="txt" value="1" />
         </counts>
       </usages-collector>
@@ -40,20 +37,20 @@
           <entry key="JSON" value="3" />
           <entry key="PLAIN_TEXT" value="2" />
           <entry key="Scratch" value="3" />
-          <entry key="TypeScript" value="29" />
+          <entry key="TypeScript" value="33" />
           <entry key="tsconfig" value="13" />
         </counts>
       </usages-collector>
       <usages-collector id="statistics.file.extensions.edit">
         <counts>
           <entry key="json" value="62" />
-          <entry key="ts" value="1633" />
+          <entry key="ts" value="2389" />
         </counts>
       </usages-collector>
       <usages-collector id="statistics.file.types.edit">
         <counts>
           <entry key="JSON" value="5" />
-          <entry key="TypeScript" value="1633" />
+          <entry key="TypeScript" value="2389" />
           <entry key="tsconfig" value="57" />
         </counts>
       </usages-collector>
@@ -74,8 +71,8 @@
       <file pinned="false" current-in-tab="true">
         <entry file="file://$PROJECT_DIR$/course/src/app/services/reportItem.service.ts">
           <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="15">
-              <caret line="1" column="3" selection-start-line="1" selection-start-column="3" selection-end-line="1" selection-end-column="3" />
+            <state relative-caret-position="110">
+              <caret line="20" column="7" selection-start-line="20" selection-start-column="7" selection-end-line="20" selection-end-column="7" />
             </state>
           </provider>
         </entry>
@@ -166,6 +163,27 @@
               <item name="Pluralsight-GetTheMostFromTypescript" type="462c0819:PsiDirectoryNode" />
               <item name="course" type="462c0819:PsiDirectoryNode" />
             </path>
+            <path>
+              <item name="Pluralsight-GetTheMostFromTypescript" type="b2602c69:ProjectViewProjectNode" />
+              <item name="Pluralsight-GetTheMostFromTypescript" type="462c0819:PsiDirectoryNode" />
+              <item name="course" type="462c0819:PsiDirectoryNode" />
+              <item name="node_modules" type="462c0819:PsiDirectoryNode" />
+            </path>
+            <path>
+              <item name="Pluralsight-GetTheMostFromTypescript" type="b2602c69:ProjectViewProjectNode" />
+              <item name="Pluralsight-GetTheMostFromTypescript" type="462c0819:PsiDirectoryNode" />
+              <item name="course" type="462c0819:PsiDirectoryNode" />
+              <item name="node_modules" type="462c0819:PsiDirectoryNode" />
+              <item name="typescript" type="462c0819:PsiDirectoryNode" />
+            </path>
+            <path>
+              <item name="Pluralsight-GetTheMostFromTypescript" type="b2602c69:ProjectViewProjectNode" />
+              <item name="Pluralsight-GetTheMostFromTypescript" type="462c0819:PsiDirectoryNode" />
+              <item name="course" type="462c0819:PsiDirectoryNode" />
+              <item name="node_modules" type="462c0819:PsiDirectoryNode" />
+              <item name="typescript" type="462c0819:PsiDirectoryNode" />
+              <item name="lib" type="462c0819:PsiDirectoryNode" />
+            </path>
             <path>
               <item name="Pluralsight-GetTheMostFromTypescript" type="b2602c69:ProjectViewProjectNode" />
               <item name="Pluralsight-GetTheMostFromTypescript" type="462c0819:PsiDirectoryNode" />
@@ -256,19 +274,19 @@
       <updated>1535304175302</updated>
       <workItem from="1535304176395" duration="75000" />
       <workItem from="1535304274687" duration="6343000" />
-      <workItem from="1535393199806" duration="3815000" />
+      <workItem from="1535393199806" duration="4896000" />
     </task>
     <servers />
   </component>
   <component name="TimeTrackingManager">
-    <option name="totallyTimeSpent" value="10233000" />
+    <option name="totallyTimeSpent" value="11314000" />
   </component>
   <component name="ToolWindowManager">
     <frame x="0" y="23" width="1440" height="877" extended-state="6" />
     <editor active="true" />
     <layout>
       <window_info id="Favorites" order="0" side_tool="true" />
-      <window_info active="true" id="Structure" order="1" side_tool="true" visible="true" weight="0.1795422" />
+      <window_info id="Structure" order="1" side_tool="true" visible="true" weight="0.1795422" />
       <window_info id="npm" order="2" side_tool="true" />
       <window_info anchor="bottom" id="Event Log" order="0" sideWeight="0.5007153" side_tool="true" weight="0.3299363" />
       <window_info anchor="bottom" id="Version Control" order="1" />
@@ -291,7 +309,7 @@
       <window_info anchor="right" content_ui="combo" id="Hierarchy" order="4" weight="0.25" />
       <window_info anchor="right" content_ui="combo" id="Project" order="5" sideWeight="0.49582636" visible="true" weight="0.27110156" />
       <window_info anchor="right" id="Remote Host" order="6" show_stripe_button="false" />
-      <window_info anchor="right" x="0" y="0" width="310" height="677" id="Documentation" order="7" sideWeight="0.50417364" side_tool="true" weight="0.27110156" />
+      <window_info active="true" anchor="right" x="0" y="0" width="310" height="677" id="Documentation" order="7" sideWeight="0.50417364" side_tool="true" visible="true" weight="0.27110156" />
     </layout>
   </component>
   <component name="TypeScriptGeneratedFilesManager">
@@ -420,10 +438,17 @@
         </state>
       </provider>
     </entry>
+    <entry file="file://$PROJECT_DIR$/course/node_modules/typescript/lib/lib.es5.d.ts">
+      <provider selected="true" editor-type-id="text-editor">
+        <state relative-caret-position="348">
+          <caret line="1374" column="5" selection-start-line="1374" selection-start-column="5" selection-end-line="1374" selection-end-column="5" />
+        </state>
+      </provider>
+    </entry>
     <entry file="file://$PROJECT_DIR$/course/src/app/services/reportItem.service.ts">
       <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="15">
-          <caret line="1" column="3" selection-start-line="1" selection-start-column="3" selection-end-line="1" selection-end-column="3" />
+        <state relative-caret-position="110">
+          <caret line="20" column="7" selection-start-line="20" selection-start-column="7" selection-end-line="20" selection-end-column="7" />
         </state>
       </provider>
     </entry>

course/src/app/services/reportItem.service.ts

@@ -17,6 +17,36 @@ export type ReportItem = {
     date: Date;
 };
 
+// A ReportItem with all keys optional.
+export type ReportItem2 = {
+    // All properties same as ReportItem.
+    // [P in keyof ReportItem]?: ReportItem[P]
+
+    // All properties optional
+    [P in keyof ReportItem]?: ReportItem[P]
+}
+
+// A Generic for any object with all keys optional.
+type Optional<T> = {
+    // All properties optional
+    [P in keyof T]?: T[P]
+}
+
+// Same as ReportItem2 but using the generic.
+export type ReportItem3 = Optional<ReportItem>;
+
+// Same again, using the TS builtin for this.
+export type ReportItem4 = Partial<ReportItem>;
+
+// All keys readonly.
+export type ReportItem5 = Readonly<ReportItem>;
+
+// ReportItem again.
+export type ReportItem6 = Required<ReportItem3>;
+
+// Only keep 3 keys
+export type ReportItem7 = Pick<ReportItem, 'date' | 'amount' | 'description' >;
+
 function validateRequired(item: ReportItem): boolean {
     // false is a valid value for these, so exclude them from check.
     const exclude: (keyof ReportItem)[] = ['hasReceipt'];