Tip #2: Using Google Sheets as UI for your n8n workflow

Very often you need more control on input and output data for your n8n workflow, i.e. store input data in tabular format, execute n8n workflow on some specific part of your data, store new fields from n8n workflow output, etc. In other words you need some kind of UI for your n8n workflow. Google Sheets is very popular and easy way to do it and also it's well intergrated with n8n. Let's create a simple Google Sheet with the fields Color, Status and Number:

Here Color is just a color name, Status can be READY or DONE and Number is a string length of Color name.

We will use this Google Sheet as UI for our n8n workflow, Color will be input data, Number will be output data and Status will control which data will be used as input data on the next execution and show which data already has an output.

Let's switch to n8n workflow and first add Google Sheets node to read all the rows with Status READY:

If you execute it you can see your tabular data with Status READY:

Now let's add a Loop node and Set node within it:

Set node should pass row_number value to output and return length of Color name which we will put into Google Sheet as Number. Also we want to update Status to DONE:

Finally let's add Google Sheets node again but for updating the rows:

It will map columns automatically and also use row_number for matching rows:

Well, let's execute and check the output:

Looks as expected and now let's check Google Sheet itself:

Nice! Google Sheet has been updated as well.

If we execute our n8n workflow again, nothing will be done because there are no more rows with Status READY. So this way we can control input values for our n8n workflow. And also we can see output values and Status.

Google Sheet for this tip is available here.

Tip #1: Testing n8n sub-workflow

Sometimes you need to move a set of nodes to a separate sub-workflow in n8n and execute it by the main workflow. It allows to make your workflow more compact and also reuse it's part in other workflows. But how to test it properly without executing it by the main workflow?

So let's start with some simple sub-workflow. Of course the first node will be Execute Sub-workflow Trigger node:

Let's add some input field:

Now let's add Manual Trigger node which will be used for testing purposes:

Next we should do the trick - add two Edit Fields (Set) nodes, one is for test input and the other one will combine the input from both triggers:

Specify color field with some test value in Test Input node:

And include all the input fields in Combine Input node:

Let's try to execute this n8n sub-workflow:

And check the input of the last node:

So you can see the same color field value we specified in Test Input node as Combine Input node output. If we execute this sub-workflow by the main n8n workflow with some color input it will be available in Combine Input node output as well.

Regardless the way we trigger our sub-workflow (manually or by main workflow) Combine Input node will always have color field value (testing value or real input from the main n8n workflow).

In further nodes you can use Combine Input node to refer to input values:

You can find the template for the described approach here.