Video 8: use GraphQLNonNull for required arguments.

.idea/workspace.xml

@@ -2,7 +2,6 @@
 <project version="4">
   <component name="ChangeListManager">
     <list default="true" id="417b6c39-7b77-43c5-80fb-b9bf95b57f36" name="Default" comment="">
-      <change type="NEW" beforePath="" afterPath="$PROJECT_DIR$/doc/concepts.dot" />
       <change type="MODIFICATION" beforePath="$PROJECT_DIR$/.idea/workspace.xml" afterPath="$PROJECT_DIR$/.idea/workspace.xml" />
       <change type="MODIFICATION" beforePath="$PROJECT_DIR$/index.js" afterPath="$PROJECT_DIR$/index.js" />
     </list>
@@ -22,8 +21,8 @@
       <file leaf-file-name="index.js" pinned="false" current-in-tab="true">
         <entry file="file://$PROJECT_DIR$/index.js">
           <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="157">
-              <caret line="38" column="3" lean-forward="true" selection-start-line="38" selection-start-column="3" selection-end-line="38" selection-end-column="3" />
+            <state relative-caret-position="98">
+              <caret line="7" column="13" lean-forward="true" selection-start-line="7" selection-start-column="13" selection-end-line="7" selection-end-column="13" />
               <folding />
             </state>
           </provider>
@@ -117,6 +116,38 @@
               <option name="myItemType" value="com.jetbrains.php.projectView.PhpTreeStructureProvider$1" />
             </PATH_ELEMENT>
           </PATH>
+          <PATH>
+            <PATH_ELEMENT>
+              <option name="myItemId" value="Egghead GraphQL" />
+              <option name="myItemType" value="com.intellij.ide.projectView.impl.nodes.ProjectViewProjectNode" />
+            </PATH_ELEMENT>
+            <PATH_ELEMENT>
+              <option name="myItemId" value="egghead" />
+              <option name="myItemType" value="com.jetbrains.php.projectView.PhpTreeStructureProvider$1" />
+            </PATH_ELEMENT>
+            <PATH_ELEMENT>
+              <option name="myItemId" value="node_modules" />
+              <option name="myItemType" value="com.jetbrains.php.projectView.PhpTreeStructureProvider$1" />
+            </PATH_ELEMENT>
+          </PATH>
+          <PATH>
+            <PATH_ELEMENT>
+              <option name="myItemId" value="Egghead GraphQL" />
+              <option name="myItemType" value="com.intellij.ide.projectView.impl.nodes.ProjectViewProjectNode" />
+            </PATH_ELEMENT>
+            <PATH_ELEMENT>
+              <option name="myItemId" value="egghead" />
+              <option name="myItemType" value="com.jetbrains.php.projectView.PhpTreeStructureProvider$1" />
+            </PATH_ELEMENT>
+            <PATH_ELEMENT>
+              <option name="myItemId" value="node_modules" />
+              <option name="myItemType" value="com.jetbrains.php.projectView.PhpTreeStructureProvider$1" />
+            </PATH_ELEMENT>
+            <PATH_ELEMENT>
+              <option name="myItemId" value="graphql" />
+              <option name="myItemType" value="com.jetbrains.php.projectView.PhpTreeStructureProvider$1" />
+            </PATH_ELEMENT>
+          </PATH>
           <PATH>
             <PATH_ELEMENT>
               <option name="myItemId" value="Egghead GraphQL" />
@@ -271,16 +302,16 @@
       <workItem from="1481822371153" duration="34000" />
       <workItem from="1481822430451" duration="270000" />
       <workItem from="1481969401352" duration="4966000" />
-      <workItem from="1481993311649" duration="1895000" />
+      <workItem from="1481993311649" duration="2661000" />
     </task>
     <servers />
   </component>
   <component name="TimeTrackingManager">
-    <option name="totallyTimeSpent" value="7690000" />
+    <option name="totallyTimeSpent" value="8456000" />
   </component>
   <component name="ToolWindowManager">
     <frame x="0" y="23" width="1435" height="877" extended-state="6" />
-    <editor active="false" />
+    <editor active="true" />
     <layout>
       <window_info id="Project" active="false" anchor="right" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="true" show_stripe_button="true" weight="0.24011503" sideWeight="0.5" order="5" side_tool="false" content_ui="combo" />
       <window_info id="TODO" active="false" anchor="bottom" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.33" sideWeight="0.5" order="10" side_tool="false" content_ui="tabs" />
@@ -291,9 +322,9 @@
       <window_info id="Run" active="false" anchor="bottom" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.2089172" sideWeight="0.5" order="6" side_tool="false" content_ui="tabs" />
       <window_info id="Structure" active="false" anchor="left" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="true" show_stripe_button="true" weight="0.22501798" sideWeight="0.5" order="1" side_tool="false" content_ui="tabs" />
       <window_info id="Mongo Explorer" active="false" anchor="right" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.33" sideWeight="0.5" order="1" side_tool="false" content_ui="tabs" />
-      <window_info id="Terminal" active="true" anchor="bottom" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="true" show_stripe_button="true" weight="0.22929937" sideWeight="0.5" order="2" side_tool="false" content_ui="tabs" />
+      <window_info id="Terminal" active="false" anchor="bottom" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.22929937" sideWeight="0.5" order="2" side_tool="false" content_ui="tabs" />
       <window_info id="Favorites" active="false" anchor="left" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.33" sideWeight="0.5" order="0" side_tool="true" content_ui="tabs" />
-      <window_info id="Debug" active="false" anchor="bottom" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.2764331" sideWeight="0.5" order="7" side_tool="false" content_ui="tabs" />
+      <window_info id="Debug" active="false" anchor="bottom" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.27515924" sideWeight="0.5" order="7" side_tool="false" content_ui="tabs" />
       <window_info id="Cvs" active="false" anchor="bottom" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.25" sideWeight="0.5" order="8" side_tool="false" content_ui="tabs" />
       <window_info id="Message" active="false" anchor="bottom" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.33" sideWeight="0.5" order="4" side_tool="false" content_ui="tabs" />
       <window_info id="Commander" active="false" anchor="right" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.4" sideWeight="0.5" order="2" side_tool="false" content_ui="tabs" />
@@ -407,10 +438,18 @@
         </state>
       </provider>
     </entry>
+    <entry file="file://$PROJECT_DIR$/node_modules/graphql/index.js">
+      <provider selected="true" editor-type-id="text-editor">
+        <state relative-caret-position="181">
+          <caret line="65" column="31" lean-forward="false" selection-start-line="65" selection-start-column="31" selection-end-line="65" selection-end-column="31" />
+          <folding />
+        </state>
+      </provider>
+    </entry>
     <entry file="file://$PROJECT_DIR$/index.js">
       <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="157">
-          <caret line="38" column="3" lean-forward="true" selection-start-line="38" selection-start-column="3" selection-end-line="38" selection-end-column="3" />
+        <state relative-caret-position="98">
+          <caret line="7" column="13" lean-forward="true" selection-start-line="7" selection-start-column="13" selection-end-line="7" selection-end-column="13" />
           <folding />
         </state>
       </provider>

index.js

@@ -3,12 +3,13 @@
 const express = require('express');
 const graphqlHTTP = require('express-graphql');
 const {
-  GraphQLSchema,
-  GraphQLObjectType,
+  GraphQLBoolean,
   GraphQLID,
-  GraphQLString,
   GraphQLInt,
-  GraphQLBoolean
+  GraphQLNonNull,
+  GraphQLObjectType,
+  GraphQLSchema,
+  GraphQLString,
 } = require('graphql');
 const { getVideoById } = require('./src/data/index');
 
@@ -47,7 +48,7 @@ const queryType = new GraphQLObjectType({
       type: videoType,
       args: {
         id: {
-          type: GraphQLID,
+          type: new GraphQLNonNull(GraphQLID),
           description: 'The ID of the video'
         }
       },