Brainwave

Tasklist Application

Hi Guys!

So, far you have learnt how to use the Brainwave Platform to create simple applications. Now we are going to look how the "Poseidon" database works and how data is being stored and retrieved from there.

For this we are going to create an application called "Tasklist". In which a user will be able to assign a task to any user including him also, and will be able to view all the tasks assigned to him. He can also delete any task from his tasklist.

Guide

Step 1: Install the Brainwave Platform in your computer. Double click on the executable file and follow the instructions.

Step 2: Install Python 2.5, available from http://www.python.org/download/releases/2.5/Python-2.5.msi. Download it and Install it.

Step 3: Download and install your favorite programmer's text editor. We use the free Notepad++ which can be downloaded from http://prdownloads.sourceforge.net/notepad-plus/npp.3.9.Installer.exe?use_mirror=umn.

Step 4: The Brainwave Platform requires Firefox 1.5 or later. Firefox can be be downloaded from http://www.mozilla.com/en-US/products/download.html?product=firefox-2.0&os=win&lang=en-USDownload & Install Firefox.

Before creating the application you need to understand the "Poseidon Database Structure". For this please refer "Poseidon Documentation".

In our application the structure will look something like this.

In the structure you can see we are creating two sets of links
First is ('user','tasklist','user_tasklist')

Second is ('user_tasklist','task','tasks')

First link will be created during the initialization of the application with p.setContext as "sys_user".
Second will be created by the default p.setContext

To create the application click on the Brainwave icon on the desktop
Or
Go to Start -> Programs -> Brainwave -> Start Brainwave.
The brainwave home page will be displayed. Click on the Application Builder icon.

The logon screen will appear. As the Brainwave Platform comes with a built-in authentication feature, you have to be logged in to view any application or to use the platform.

It will open the application builder application.

Enter 'Tasklist' as the application name or any name you want to give. Now follow the tutorial on the right side of the screen.

Go to the created Tasklist folder 'C:/Program Files/Brainwave/Apps/Tasklist', there you will see a file Tasklist.py. Open it in Notepad++.

We need to create the first link for every user. So, we are going to write the following code in the def __init__(self) method

def __init__(self):
		
		iris.App.__init__(self)
		self.aphrodite = aphrodite.Aphrodite('tasklist')
		
		p=self.findObject('poseidon')
		
		p.setContext('sys_user','sys_user')
		
		Idea.setPoseidon(p)
		
		users = Idea.findAll('user')
		tasklist_verb = self.createNamespace(p, "tasklist.tasklist", save=False)['o']
		for x in users:
			
			user_id = x.get_id()
			user_list = x.findValues('tasklist')
			user_name = x.get_name()
			
			if len(user_list)<1:
				
				
				p.addCapability(user_id, 'read', user_list_id, save=False)
				p.addCapability(user_id, 'write', user_list_id, save=False)
				p.addCapability(user_id, 'link', user_list_id, save=False)
				
				p.setPolicy(user_list_id,'write','True',save=False)
				p.addLink(user_id, tasklist_verb, user_list_id)
				p.save()

First we are setting the reference of the 'Poseidon' Database to p.
Then we are setting the p.setContext ('sys_user','sys_user') in order to create the first link. So, that every user could have access to it.
Next we are passing the Database reference to Idea. So, that it could search the database.
Then we are creating a list (users) of all the users, by using idea to find all the users exist in the database.
And also we are creating the NameSpace for the 'tasklist' word.
Next for every user we are creating a list (user_list) of the tasklist by using Idea to find the values 'tasklist' for every 'x' i.e for every user.
Repeating the same procedure for the 'user_id's and 'user_name'.
Then checking each user to see the user_list. If the user_list doesn't exist, create the link, adding capabilities and setting the global p.setPolicy('write') to True.

So, far we have created the First Link for any user.

Now we are going to define the index method. Here we are trying to find out, if any tasks were there in the database for the current user. If yes, then it will print them on the screen.

@iris.expose
	def index(self, *args, **kwargs):
		p=self.findObject('poseidon')
		users = Idea.findAll('user')
		user_tasks = Idea.get(iris.session['uid']).findValues("tasklist")
		tasks = Idea.get(user_tasks[0]['__id']).findValues("task")
		return CheetahRender(data={'users':users,'tasks':tasks},template="index")

First, we find out the all the users.
Then for the current user, we find his/her tasklists.
Next print the tasklist on the screen for the current user along with a list of all the users.
In order to print we passing the data to the Index template file.

Now we are going to create the interface of the application i.e the Index template file. Write the following code into the "index.tmpl" file

#filter WebSafe
<window>
	<div style="width:100%;text-align:center;margin:0 auto;">
		<p>
		<div class="box" style="width:700px;height:350px;margin:0 auto;">		
			<div class="boxtitle" style="text-align:center;font:25 Times New Roman"><b>Tasklist</b></div>
				<p/>
				<table>
					<tr>
						<td width="200" align="center">
							<div style="border:1px solid #ccc;font:16 Times New Roman"><b>Tasks</b></div>
						</td>
						<td width="500" align = "center">
							<div style="border:1px solid #ccc;font:16 Times New Roman"><b>Create and Assign Task</b></div>
						</td>
					</tr>
				
					<tr>
						<td width="250">
							<div id="tasklist" style="border:1px solid #ccc;height:250px;padding-left:10px;overflow:auto">
								<ol>
								#for $task in $tasks
								<li id="${task.get_id()}">$task.get_name()
									<button image="del" update="tasklist" url="/tasklist/remove/]]><![CDATA[$]]><![CDATA[{task.get_id()}" />
								</li>
	
								</ol>
								</div>
						</td>
						<td width="350">
							<div style="border:1px solid #ccc;height:250px;padding-left:10px"><p/>
								<ajaxform id="createtask" url="/tasklist/create" method="get" update="tasklist">
									<table>
										<tr>
											<td><input type="text" name="task" id='task_box' style="width:225px;"/></td>
											<td><select name="user" style="width:150px; height:21px;">]]>
											<#><for> <$><users in> <$><users>
											<<option value='><$><!users.__id'>><$><users.__name</option>>
											<#><end for

											
											</select></td>
											<td><button image="go" submit="createtask" url="/tasklist/create" update="task_box=''"/></td>
										</tr>
										<tr align="center">
											<td><label>Task</label></td>
											<td><label>Assigned to</label></td>
										</tr>
									</table>
								</ajaxform>
							<br/><p/>
							</div>
						</td>
					</tr>
					
				</table>	
			</div>
		</p>
	</div>
</window>

The interface will look this.

Now we are going to create the 'create method' for creating the tasks.

@iris.expose
	def create(self, *args, **kwargs):
		p=self.findObject('poseidon')
		del kwargs['_']
		
		u_def_task= p.addMeme(kwargs['task'])[0].id
		
		if p.getNeuron('task') is None:
			ver = p.addMeme('task')[0].id
			p.setPolicy(ver,'write','True',save=False)
			p.save()
		else:
			ver = p.getNeuron('task')[0].id
			
		user_tasklist = Idea.get(kwargs['user']).findValues("tasklist")
		
		p.addLink(user_tasklist[0]['__id'],ver,u_def_task)
		p.addLink(u_def_task,p.addMeme('is a')[0].id,ver)
		p.save()
		
		user_tasks = Idea.get(iris.session['uid']).findValues("tasklist")
		tasks = Idea.get(user_tasks[0]['__id']).findValues("task")
		return CheetahRender(data={'tasks':tasks},template="tasklist")

This function is going to be called by the create button image with params (user,task), which are then passed to function through kwargs.
So here we are going to the extract the 'Task' defined by the user from the kwargs and save it in the database.
Next we are searching for the 'task' Neuron, whether it is there in the database. If it is there, save the id of the neuron, else create it and set its set.Policy('write') to true.
Next we find the user_tasklist of the user to whom the task is being assigned. So, here code is going to get kwargs['user'] from the database and find the values ('tasklist').
Then we are create the second link ('user_tasklist','task','tasks').
In order to keep the database structure, we have create another link i.e ('tasks','is a','task').
For the current user we are finding out his/her ('tasklist') values.
Based on the 'tasklist' finding out his/her tasks.
Next we send the retrieved or created data tasks to the 'Tasklist' template file.

To view the tasks create the tasklist.tmpl and put the following code there.

#filter WebSafe
<ol>
	#for $task in $tasks
		<li>$task
			<button image="del" />
		</li>
	#end for
</ol>

Here we display the tasks along with an image button to delete the task.

Now lets create a task for the current user himself.

Once we are able to create tasks, let's create another method to delete the tasks.

@iris.expose
	def remove(self, *args, **kwargs):
		p=self.findObject('poseidon')
		
		user_tasklist = Idea.get(iris.session['uid']).findValues('tasklist')
				
		pol=p.addLink(user_tasklist[0]['__id'],p.getNeuron('task')[0].id,args[0])
		
		p.removeLink(pol.id)
		
		user_tasks = Idea.get(iris.session['uid']).findValues("tasklist")
		
		tasks = Idea.get(user_tasks[0]['__id']).findValues("task")
		
		return CheetahRender(data={'tasks':tasks},template="tasklist")

When the user will click on the delete image the 'remove' method or function will be called passing the 'task.id' as kwargs.
Then we find out the 'tasklist' values for the current user get the id of the first link i.e ('user','tasklist','user_tasklist') for the current user by addlink (returns the link id, if it exist, otherwise creates a new one).
And then remove the link by passing its id.
Finally, find the data for the current user and send it back to the screen, to reload the tasklist.