How to: Build a Simple Looping Data Workflow

Iterators, like the Data Workflow component, often handle only one element of an array at a time. But what if you need to repeat the process to iterate on more elements? In this how-to guide, you’ll learn about a looping Data Workflow to achieve this task.  is and how to build one.

What Is a Looping Data Workflow?

Looping Data Workflows let you perform operations on consecutive rows of an array. Imagine you have a list of clients you need to email a renewal notice to. You might have that list in a table like the following:

To send out these emails manually, you’d use the following process:

1. Look at the list of clients, and see who needs to be emailed.

2. Retrieve the necessary details from the first row.

3. Complete and send the email to the first client.

4. Return to the list and see if others need to be emailed.

5. Repeat Steps 2 through 4 until each client on the list has been emailed.

But you don't want to send a generic email to every person on your list. Instead, you want to send a personalized email that follows this template:

To: {{clientEmail}}

Hello {{clientName}},

This is a notification that your product license for {{product}} will renew next year for {{renewalPrice}}. Please contact your account manager if you have any questions.

Best,

Our Company Services                                        

To see how this process works with a looping Data Workflow, look at the following diagram.

Here, Step 1 is some form of an input. In our example, this would be a table storing your client data. Step 2 is some form of logic to determine which row is next. In our case, it looks for which index in your table is next. Data from the next index is sent into the operation, which is represented by Step 3. In our case, this operation is sending an email to your client. At Step 2, if there are no additional indexes to process, the loop finishes. Then, it concludes at Step 4.

Configuration

This configuration can seem complex, but keep in mind the five steps you'd take to send these emails manually.

These instructions assume you have a new module open, saved, and with a title.

Configure the Data Table Component

Begin by configuring a Data Table component to store your client list and their information.

1. In the Module Builder, drag and drop a Data Table component onto your canvas.

2. In the Property ID and Label Text fields, enter dtClients.

3. In the data table, enter the following:

   #	clientName	clientEmail	product	renewalPrice
   1	Chelsea	chelsea@therainbowcompany.com	Many Hue	$1,999
   2	Noor	noor@thebuildingcompany.com	Construct It	$3,500
   3	Jadzia	jadzia@thebigcompany.com	Oversize	$70,000
   4	Alejandro	alejandro@thestartup.com	Grow Up	$1,000

   

4. Click Save Component.

Configure the First Hidden Component

Each row in your table has a number assigned to it. That number is called the index. Use a Hidden component to add a place for your application to keep track of which row it last processed. Indexes start at 0, indicating the first row. So, set the Default Value to 0. Later, you’ll add logic that increases this number, one value at a time.

1. Drag and drop a Hidden component onto your canvas, placing it below your Data Table component.

2. In the Property ID and Label Text fields, enter index.

3. In the Default Value field, enter 0.

4. Click Save Component.

Configure the First Data Workflow Component

Next, configure a Data Workflow component to create your looping logic.

1. Drag and drop a Data Workflow component onto your canvas, placing it below your Hidden component.

2. In the Property ID and Canvas Label Text fields, enter dwfLoop.

Configure the First Input Operator

This Input operator references your index Hidden component, which determines the row in your data table that needs processing next.

1. Drag and drop an Input operator onto your Data Workflow canvas.

2. Configure the operator's Info window as follows:

   Setting	Value
   Category	Input
   Component	index
   Required	Yes
   Source	Default

Configure the First Formula Operator

This Formula operator takes the previous index that was processed (A) and adds 1 to it.

The A value acts as an alias for values passed to the operator.

1. Drag and drop a Formula operator onto your Data Workflow canvas.

2. Configure the operator's Info window as follows:

   Setting	Value
   Category	Formula Value
   Label	Index + 1
   Formula/Expression	=SUM(A,1)

3. Connect the output port (right) of the Input operator to the input port (left) of the Formula operator.

Configure the First Output Operator

This Output operator outputs the data from the Formula operator to the index Hidden component. The formula updates the Hidden component’s Default Value by adding 1 to it. Now, with each loop of the Data Workflow, the value passed to the index Input operator increases by 1.

1. Drag and drop an Output operator onto your Data Workflow canvas.

2. Configure the operator's Info window as follows:

   Setting	Value
   Category	Output
   Component	index
   Action	value

3. Connect the output port (right) of the Formula operator to the input port (left) of the Output operator.

Configure the Second Input Operator

This Input operator brings your actual client data into your Data Workflow.

1. Drag and drop another Input operator onto your Data Workflow canvas.

2. Configure the operator's Info window as follows:

   Setting	Value
   Category	Input
   Component	dtClients
   Required	Yes
   Source	Default

Configure the Size Operator

For your Data Workflow to understand when all the data has been processed, you’ll use a Size operator to count the number of objects in the array. Meaning the number of clients in your table.

1. Drag and drop a Size operator onto your Data Workflow canvas.

2. Configure the operator's Info window as follows:

   Setting	Value
   Category	Size
   Label	How many clients are there?

3. Connect the output port (right) of the dtClients Input operator to the input port (left) of the Size operator.

Configure the Second Formula Operator

This Formula operator creates an expression that determines if your index Hidden component is less than the value returned by your Size operator. You’ll use the following expression: =CONCATENATE(A,"<",_arg), where A is the value from your index Hidden component and _arg is the value located by your Size operator. Later, you’ll use a Decision operator to determine whether this statement is true.

1. Drag and drop another Formula operator onto your Data Workflow canvas.

2. Configure the operator's Info window as follows:

   Setting	Value
   Category	Formula Value
   Label	More clients?
   Formula/Expression	=CONCATENATE(A,"<",_arg)

3. Connect the output port (right) of the index Input operator to the input port (left) of the More clients? Formula operator.

4. Connect the output port (right) of the Size operator to the argument port (top) of the More clients? Formula operator.

Configure the First Console Operator

You’ll add several Console operators during this configuration to view the data in the DevTools Console in Express View. This Console operator lets you view the result of your More clients? Formula operator.

1. Drag and drop a Console operator onto your Data Workflow canvas.

2. Configure the operator's Info window as follows:

   Setting	Value
   Category	Console
   Label	Condition

3. Connect the output port (right) of the More clients? Formula operator to the input port (left) of the Console operator.

Configure the Decision Operator

This Decision operator determines whether there are more emails to send by looking at the expression created by your More clients? Formula operator. If this expression is true, the Decision operator passes your data through its upper output port. If this expression is false, the Decision operator passes your data through its lower output port. So, your dtClients Input operator serves as the input and your More clients? Formula operator serves as the argument.

Your Data Workflow should continue to loop until there are no more rows to input from your Data Table component. So, you're using A<_arg to determine if the number stored in the index Hidden component is less than the total number of rows in the table. After the first loop of the Data Workflow, the value stored in the index Hidden component is 1. In the next loop, the Data Workflow processes the second row of the table (index 1). After your Data Workflow processes the fourth and final row of the table, the value stored in the index Hidden component is 4. This is no longer less than four, so in the next loop, the Decision operator evaluates the A<_arg statement as false to stop the loop.

1. Drag and drop a Decision operator onto your Data Workflow canvas.

2. Configure the operator's Info window as follows:

   Setting	Value
   Category	Decision
   Input List
   Condition	_arg

3. Connect the output port (right) of the dtClients Input operator to the input port (left) of the Decision operator.

4. Connect the output port (right) of the More clients? Formula operator to the argument port (top) of the Decision operator.

Configure the Second Console Operator

This Console operator lets you view the data your Decision operator passes to its upper input port.

1. Drag and drop another Console operator onto your Data Workflow canvas.

2. Configure the operator's Info window as follows:

   Setting	Value
   Category	Console
   Label	True

3. Connect the upper output port (right) of the Decision operator to the input port (left) of the True Console operator.

Configure the Third Console Operator

This Console operator lets you view the data your Decision operator passes to its lower input port.

1. Drag and drop another Console operator onto your Data Workflow canvas.

2. Configure the operator's Info window as follows:

   Setting	Value
   Category	Console
   Label	False

3. Connect the lower output port (right) of the Decision operator to the input port (left) of the False Console operator.

Configure the Get Operator

Once you've determined if there are more emails to send, the next step is to retrieve the data needed to send the next email. Here, you’ll connect a Get operator to your Decision operator so your dtClients Data Table component data passes through. Then, set your index Input operator as the argument to remind the Get operator which row of your table is next.

1. Drag and drop a Get operator onto your Data Workflow canvas.

2. Configure the operator's Info window as follows:

   Setting	Value
   Category	Get
   Label	Get Current Row
   Path	[_arg]

3. Connect the upper output port (right) of the Decision operator to the input port (left) of the Get operator.

4. Connect the output port (right) of the Index Input operator to the argument port (top) of the Get operator.

Configure the Fourth Console Operator

This Console operator lets you view the data retrieved by the Get operator.

1. Drag and drop another Console operator onto your Data Workflow canvas.

2. Configure the operator's Info window as follows:

   Setting	Value
   Category	Console
   Label	Current Row

3. Connect the output port (right) of the Get operator to the input port (left) of the Current Row Console operator.

   

4. Click Save Component.

Configure the Second Hidden Component

Before configuring the rest of your Data Workflow, add a place to store the results. This Hidden component stores each row of data retrieved by your Get operator. Your loop overwrites this each time it runs. So, this component only stores the row you're currently emailing.

1. Drag and drop a Hidden component onto your canvas, placing it below your Data Workflow component.

2. In the Property ID and Label Text fields, enter currentRow.

3. Click Save Component.

Update the First Data Workflow Component

Now that you have a Hidden component to store the results, you’ll update your Data Workflow component to output the data to this Hidden component. Then, you’ll reference this data in a separate Data Workflow later. The second Data Workflow sends your emails, while the first manages your loop.

1. Hover over the dwfLoop Data Workflow component.

   A toolbar displays above the component on hover-over.

2. Using the toolbar, click the (Settings) button.

Configure the Second Output Operator

This Output operator sends the data to your currentRow Hidden component.

1. Drag and drop another Output operator onto your Data Workflow canvas.

2. Configure the operator's Info window as follows:

   Setting	Value
   Category	Output
   Component	currentRow
   Action	value

3. Connect the output port (right) of the Get operator to the input port (left) of the currentRow Output operator.

4. Click Save Component.

Configure the Second Data Workflow Component

Now that you have your loop configured, set up another Data Workflow component to send your emails.

1. Drag and drop another Data Workflow component onto your canvas, placing it below your currentRow Hidden component.

2. In the Property ID and Canvas Label Text fields, enter dwfOperation.

Configure the Input Operator

This Input operator brings in the data stored in your currentRow Hidden component. When sending your emails, you’ll reference this component instead of the larger data table because it stores the data for a single client at a time.

1. Drag and drop an Input operator onto your Data Workflow canvas.

2. Configure the operator's Info window as follows:

   Setting	Value
   Category	Input
   Component	currentRow
   Required	Yes
   Source	Default

Configure the Console Operator

This Console operator lets you view the data retrieved from the currentRow Hidden component.

1. Drag and drop a Console operator onto your Data Workflow canvas.

2. Configure the operator's Info window as follows:

   Setting	Value
   Category	Console
   Label	Email Sent

3. Connect the output port (right) of the Input operator to the input port (left) of the Console operator.

Configure the Output Operator

Next, add an Output operator to trigger your first Data Workflow to run again once an email is sent.

1. Drag and drop an Output operator onto your Data Workflow canvas.

2. Configure the operator's Info window as follows:

   Setting	Value
   Category	Output
   Component	dwfLoop
   Action	trigger

3. Connect the output port (right) of the Input operator to the input port (left) of the Output operator.

   

4. Click Save Component.

Update the First Data Workflow Component

Now that you have a Data Workflow configured to run your operation, configure your first Data Workflow to trigger it. Doing so stops the loop once everyone is sent an email.

1. Hover over the dwfLoop Data Workflow.

   A toolbar displays above the component on hover-over.

2. Using the toolbar, click the (Settings) button.

Configure the Third Output Operator

Configure another Output operator to trigger the second Data Workflow to run.

1. Drag and drop another Output operator onto your Data Workflow canvas.

2. Configure the operator's Info window as follows:

   Setting	Value
   Category	Output
   Component	dwfOperation
   Action	trigger

3. Connect the output port (right) of the Get operator to the input port (left) of the dwfOperation Output operator.

Configure the Fourth Output Operator

Remember, your Decision operator determines whether there are more emails to send. If there aren't, the Decision operator passes data to its lower output port. So, you’ll add an Output operator to stop the looping process.

1. Drag and drop another Output operator onto your Data Workflow canvas.

2. Configure the operator's Info window as follows:

   Setting	Value
   Category	Output
   Component	_self
   Action	value

3. Connect the lower output port (right) of the Decision operator to the input port (left) of the _self Output operator.

4. Click Save Component.

Configure the Initializer Component

Lastly, add an Initializer component to begin the entire process.

1. Drag and drop an Initializer component onto your canvas, placing it above your Data Table component.

2. In the Property ID and Canvas Label Text fields, enter initLoop.

3. From the Trigger Type drop-down, select New Submission.

4. In the Outputs table, enter the following:

   #	Source	Type	Value
   1	dwfLoop	trigger	GO

   

5. Click Save Component.

6. Save your module.

Here's how your module looks in the Module Builder:

Preview your module in Express View and open the DevTools Console. Activity from your various Console operators populates, showing the loop is working correctly.

The first section of the image displays the path your first row of data takes through your Data Workflows. Your Condition Console operator displays the expression of 0<4 because it’s the 0 index in your data, and there are 4 items in your table. The True Console operator displays your original data, and the False Console operator displays _BLOCKED because the expression 0<4 is true. From there, your first row of data is separated. You can see this in your Current Row Console operator. Then, you also see that data in your Email Sent Console operator, indicating the data has passed through your second Data Workflow. The Console operators below this data display the rest of your data through the same process. You can expand this data in your DevTools Console to see more details.

The second portion of this image displays where your loop ends. Here, you see 4<4 in the Condition Console operator, showing that your Data Workflow has processed your data with an index of 4. Because 4<4 is a false statement, your data takes that path instead. The True Console operator displays _BLOCKED, and now your data displays under the False Console operator. Once your loop reaches this point, the process stops.