qRules 4.2 is coming soon, and with it - big changes to the SubmitToSharePointList command! But wait - don't panic - if you have a 4.1 injected form that is doing what you need, the command is backward compatible. You'll be able to inject with 4.2 and use all the awesome new string, math and financial commands without worrying about making any changes to your SubmitToSharePointList command.
Since the last walkthrough I did on this command was way back when we introduced it, I thought it was about time for a re-do. I've got another blog post that talks in general terms about the changes we've made, and one that explains the mapping file in more detail than you probably really want, so take a look at those if you are interested in any of the nitty gritty details.
Here's a link to my very favorite SharePoint template, and one that I plan to use for this walkthrough - If you are like me and the Northwind data makes you a little misty, you'll love this SharePoint template - it comes pre-loaded with Northwind data! We will be using the Customers, Orders and Order Details lists - our form will use qRules to submit to all three of them, with just one submit connection, and just one mapping file! Fasten your seatbelts, and here we go ....
The Form
First, we'll create a simple form. In case you'd be happier not having to do this yourself, you can find my form here - just a warning, it is pretty bare bones, we'll add to it as we go along. Oh, if you are wondering how I was able to add multiple fields with the same name - I added a reference to the field in the Data Source Task Pane. You can learn a bit more about that here, or towards the end of your qRules user guide.
Here's my schema:

The Customer, Employee and Ship Via columns in my SharePoint Orders list are lookups - we'll have to handle those specially. So is the Product column in the Order Details list.
The Mapping
First, we'll create our mapping file. If you have not already installed the InfoPath to SharePoint List Tool form that comes with qRules, you'll want to do that first - you can find more info starting on about page 3 of your qRules user guide.
Open the mapping tool:

EDIT: In qRules 4.3, we changed the installation process for the full trust forms. If you are using v4.3 or later, you'll see this in your start menu:

Clicking on qRules Forms in the start menu opens a folder:

The mapping tool is there, along with an installer for the form and instructions on how to install the form. Once the form has been installed, you can either access it directly from the folder, or by opening InfoPath Filler and opening the form from there:

Under the Define Mapping tab, attach your XSN file and enter your SharePoint URL:

Click the Get SharePoint Lists button to expand the Mapping Definition section of the form and allow you to pick the lists you wish to map to.
In qRules 4.2, our lists will be submitted to in the order they are mapped. In our form, the parent list is the Customers list, then the Orders list, and finally, the Order Details list. So, we will map our data in that order. Also, in our form, the Customer is not repeating, but we can have multiple orders and multiple order details.
First, we'll map our customer information. Select the Customers list from the SharePoint List drop down control:

Click the ... button next to the FormField:

This will display the form fields in the task pane:

Double click the ShPId field. We are going to use this field for the Customers list item id. It doesn't get mapped to a column - on a successful submit, qRules will populate it with the newly created item's id, so we can update our list item from our form. Click the Show button in the Options column, and select Id - your first column mapping will look like this:

Map the rest of the fields - these are all from the Customer group in my form template schema:

Click the widget to insert another SharePoint Mapping - we are now going to map the Orders group to the Orders list:

We want to map our lists in the order we want them to submit, as I mentioned above, since qRules will process the mapping file sequentially (unless we specify the /mappingName parameter in the command). Because we want to submit our new Customer list item id with our Order for the Customer lookup, we want the Customer mapping to submit first, so the field we've indicated as the id is populated prior to submitting the Order.
Here's my partially completed Order mapping:

I have only filled out the Form Fields that can be selected using the field picker task pane at this point. This is a repeating group, so I have indicated that, and selected the group in the Repeating Group field.
I'm going to enter the XPath for the remaining mappings by hand - that's because they need to be relative to the repeating group itself.
My repeating group is: my:myFields/my:Customer/my:Orders/my:Order
The other information I want is in my Customer group - I have to go up the tree twice: ../../
That takes me from my:Order back up to my:Orders (../) and then again back up to my:Customer (../). When in doubt, let InfoPath figure it out - if I need a relative XPath and am not sure what it would be, I leverage InfoPath - here's a short post on that.
Now, I realize that my form may be working from an unrealistic conceit, but for my scenario, my Customer address information will be my Shipping Address information. My finished mapping, then, once I have carefully hand typed the relative paths to my Customer info, looks like this:

Notice I'm going to submit the ShpId field for the Customer to the Customer column in my Order list? That is because to set the value for a lookup column, I need to submit the item's id. When my customer is created in the Customers list, that field (/my:myFields/my:Customer/my:ShpId) will be populated with the new customer id. To link my Order to my Customer, I'll want to submit that very same id to the Customer column in my Orders list.
Finally, we insert yet another SharePoint mapping for the template - this time, I'll be mapping to the Order Details list:

This time, I'm including a relative path to the OrderNumber field - while my list has an Order Number column, it is not a lookup. Thus, I want to submit the actual OrderNumber value, not the id of the Order list item.
Finally, click the Save as qRules Mapping button:

The saved mapping will default the name to mapping.xml - I usually just leave that as is. In case you'd like it, my mapping is available here - keep in mind that even if you are using the same SharePoint template, your URL and list GUIDs will be different from mine.
The Data Connections
Now we will add our mapping file, mapping data connection, and submit data connection to our form. I have a rather specific way I like to add my XML resource files - I like to implicitly add the resource file instead of letting InfoPath do it, as InfoPath strips off the XML file extension when it "helps" you - since my mapping data connection schema won't change, if I add the resource file myself it makes it simpler when I decide to change the mapping.
From InfoPath, select the Data tab on the Ribbon, then From Other Sources --> From XML File:

Click the Resource Files button:

Click the Add button in the Resource Files dialog, and select the mapping.xml saved earlier:

Click OK, then Next and Finish - the default name for your mapping data connection will be mapping - just leave that as is, and leave the checkbox to load data on open selected. In the data connections dialog, the details for your data connection should look like this:

Next, we need to add a Submit data connection to the UpdateListItems method of the SharePoint Lists web service. On the Data tab of the Ribbon, select To Other Locations --> To Web Service:

The URL for the Lists web service is: http://YourServer/_vti_bin/lists.asmx - replace "YourServer" with your actual server name. If in doubt, test your URL in a browser, making sure you get a page that looks like this:

After entering the URL in the Data Connection Wizard, click Next and select the UpdateListItems method:

Click Next again and leave the parameters blank in the following dialog - just click Next and Yes on the warning:

qRules will populate the data for the submit parameters. In the final window, I usually deselect the checkbox for using the connection as the submit default, and I generally give my connection a simpler name:

Make a note of the name you use - including the casing - as you will need it for your command.
Handling Special Fields
I mentioned earlier that we would need to handle the lookup fields in a special manner - we need to make sure we are submitting valid list item ids for those fields. So, we need to add data connections in our form to the following lists:
-
Employees
-
Products
-
Shippers
You can use the From SharePoint List button on the Data tab of the Ribbon to create these connections. Be sure you select the ID field as well as whatever field you'd like to use for display in a drop down - like the Employee Name, Product Name or Company Name. After all your data connections have been created, your form's Data Connections will look like this:

If you need help creating a SharePoint List data connection, here's an Office Online article that may be of use.
In the form, we'll use these new data connections as data sources for drop down controls - we need to use drop downs for the Employee, Ship Via and Product fields:

Here's my form thus far, in case you need it - the important thing to remember is that the value for these drop down controls needs to be the list item id:

When we test our command, I'll show you what happens if we submit incorrect data to a lookup - I know you won't want to miss that!
Add the qRules SubmitToSharePointList Command
Oh, finally. We are at that point where we can add our command. And guess what? This will be the shortest section of the entire blog post. First, you'll need to inject your template with qRules. Save and close your form template, and from the Start menu, navigate to Qdabra / Tools and find your qRules folder - open the injector and inject your form. If you need more detail, qRules installs with a Quick Start guide that you'll find helpful.
After injecting, open your form in design mode, add a button to your form, and add an action rule to the button:

The Action should set the Command node in the QdabraRules data source:

The value we will set the Command node to is:
SubmitToSharePointList /submit=ShPList

Remember several thousand words ago, when I suggested you make note of the name of your UpdateListItems method data connection? This is why - the value to the right of the "=" sign needs to be the exact name of your SharePoint Lists web service data connection - including the casing. So, if yours is named MyFancySharePointSubmit your command would be SubmitToSharePointList /submit=MyFancySharePointSubmit.
I'm also assuming you followed along and left your mapping data connection named mapping - if it is named anything else, you'll need to include the /mapping parameter (SubmitToSharePointList /submit=MyFancySharePointSubmit /mapping=MyMappingThatIRenamedToBeDifficultAboutThings for example).
Test Your Form!
First, from the QdabraRules data source, drag the Error node onto your form:

You can also drag the Success node onto the form if you like.
Then, preview the form. Fill out some data:

And click the Submit button.....
If the Error node is blank (and Success is checked as true), go take a look at your lists, and do a little happy dance at your desk (it's okay, I won't tell anyone).
Here's what my lists look like -
Customers:

Orders:

Order Details:

Hang onto your form - we'll use it again in some future blog posts. We still haven't talked about adding attachments or refreshing our form data, and I've not even mentioned updating.... So much to say, so little space. But, before you race off to other, more exciting blogs, one last thing....
Troubleshooting
What if your form didn't submit? You have an error? Let's take a look at an issue I mentioned earlier - that your data won't submit if you have invalid values submitting to a lookup.
I've added the ShipVia field to my form again, but as a text box:

I'll fill out the form partially - and deliberately put bad data in that field:

When I click my button, I get an error:

That little gem is courtesy of SharePoint - not too helpful, is it. When I get errors like this, I usually do a web search with the error message and the name of the web method (UpdateListItems) - generally I can find enough clues to get me headed down the right path. For the sake of future searches - The operation failed because an unexpected error occurred. (Result Code: 0x80020005) from the UpdateListItems method may mean you are trying to set a lookup column to an invalid value!
Be sure to search this forum on errors as well, and if you have an issue you can't resolve, create a new thread in the qRules forum, so we can help you get it figured out.
***********************
Hey, I did a video walkthrough on this - you can find that here.
More posts coming soon on adding attachments to our list items, updating existing list items from InfoPath, refreshing the list items in our form, submitting only specific mappings, and other diverse topics of interest. Hang onto your form from this walkthrough, since I'll be using the same form for these future posts. I hope you are as excited about qRules 4.2 as I am!
***********************
Working with Attachments
Submitting a Single Mapping / Updating Existing Data
RefreshSharePointListItems