[FIXED JENKINS-35410] Improve User Experience

src/main/java/hudson/plugins/batch_task/BatchTaskInvoker.java

@@ -10,16 +10,20 @@
 import hudson.model.Cause.UpstreamCause;
 import hudson.model.CauseAction;
 import hudson.model.Descriptor;
+import hudson.model.Item;
 import hudson.model.ItemGroup;
 import hudson.model.Result;
 import hudson.model.Run;
 import hudson.tasks.BuildStepDescriptor;
 import hudson.tasks.BuildStepMonitor;
 import hudson.tasks.Notifier;
 import hudson.tasks.Publisher;
+import hudson.util.FormValidation;
 import hudson.util.ListBoxModel;
 import jenkins.model.Jenkins;
 import net.sf.json.JSONObject;
+import org.kohsuke.accmod.Restricted;
+import org.kohsuke.accmod.restrictions.NoExternalUse;
 import org.kohsuke.stapler.AncestorInPath;
 import org.kohsuke.stapler.DataBoundConstructor;
 import org.kohsuke.stapler.QueryParameter;
@@ -139,6 +143,29 @@ public ListBoxModel doFillTaskItems(@QueryParameter String project, @AncestorInP
                 }
                 return r;
             }
+
+            @Restricted(NoExternalUse.class)
+            public FormValidation doCheckProject(@QueryParameter String project) {
+                if (project.startsWith("/")) {
+                    return FormValidation.warning(Messages.BatchTaskInvoker_ForwardSlash());
+                }
+                Jenkins jenkins = Jenkins.getInstance();
+                if (jenkins != null) {
+                    Item item = jenkins.getItemByFullName(project);
+                    if (item == null) {
+                        return FormValidation.warning(Messages.BatchTaskInvoker_NoSuchProject(project));
+                    }
+                }
+                return FormValidation.ok();
+            }
+
+            @Restricted(NoExternalUse.class)
+            public FormValidation doCheckTask(@QueryParameter String project, @QueryParameter String task) {
+                if (!project.isEmpty() && task.isEmpty()) {
+                    return FormValidation.warning(Messages.BatchTaskInvoker_NoBatchTaskExists(task));
+                }
+                return FormValidation.ok();
+            }
         }
     }
 

src/main/resources/hudson/plugins/batch_task/BatchTaskInvoker/Config/help-project.html

@@ -0,0 +1,11 @@
+<div>
+    The <strong>Full project name</strong>
+
+    <p>
+        For jobs inside a folder it is always a path like <strong>foo/bar</strong>
+    </p>
+
+    <p>
+        In Jenkins <strong>Full project name</strong> cannot start by "/"
+    </p>
+</div>

src/main/resources/hudson/plugins/batch_task/BatchTaskInvoker/Config/help-task.html

@@ -0,0 +1,7 @@
+<div>
+    List of tasks contained on the Project.
+
+    <p>
+        Empty means there is not any task on the selected Project.
+    </p>
+</div>

src/main/resources/hudson/plugins/batch_task/Messages.properties

@@ -6,3 +6,4 @@ BatchTaskInvoker.NoSuchProject=No such project exists: {0}
 BatchTaskInvoker.NoSuchTask=No such task exists: {0}. Perhaps you meant {1}
 BatchTaskAction.DisplayName={0,choice,1#Task|1<Tasks}
 BatchRunAction.DisplayName=Executed Tasks
+BatchTaskInvoker.ForwardSlash=Project should be a Full Project Name which cannot start by /. Current settings may lead to the undefined behavior.