Calculate the years since a milestone

You can build a Flow to calculate the years since an important date, such as an anniversary, when one of your customers opened an account, or another important milestone.

In this tutorial, you'll create a new Flow that calculates the years since Postman's founders founded the company. However, feel free to use your own milestone instead.

Create a new Flow

You build Flows in a workspace. Workspaces let you organize your API projects and collaborate with your team.

To create a new Flow, do the following:

1. Choose an existing workspace or create a new one.
2. From the Postman sidebar, select Flows.
3. Select Create a new Flow > Create new Flow.
4. Enter a name. For example, enter Calculate years since a milestone.
5. Select the Return or Enter key.

Create a variable for the current date and time

When you run a Flow, the Now block gives you the current date and time, which you'll need to calculate the years since the milestone.

Add a Now block

1. From the canvas toolbar, select Block.
2. Select Now. If you want to search for the block, enter Now in search.
3. Decide where on the canvas you want to place the Now block and select that location.

Connect a Create Variable block

When you connect two blocks, you connect one block's input to another block's output. Inputs are on the block's left side and outputs are on its right side.

It's optional to connect a Create Variable block. However, if you plan to use a value in multiple places, the best practice is to create a variable. These steps will also let you separate your logic.

To connect a Create Variable block, do the following:

1. Hover over the Now block's output port. The pointer changes to a crosshair.
2. Decide where on the canvas you want to place the Create Variable block and drag the port to that location.
3. Select Create Variable. If you want to search for the block, enter Create Variable in search.
4. Enter the variable's name. For example, enter now.

Group your blocks

In this tutorial, you'll separate the logic to get the current date and time from the logic to calculate the years since the milestone and other logic. You can group blocks to better separate this logic.

To group your blocks, do the following:

1. Select and hold the Command or Ctrl key.
2. Select the blocks you want to group. The canvas's flyout menu appears and displays the number of blocks you selected.
3. Hover over the canvas's flyout menu and select Group selection.
4. Hover over the group's title and select Edit title.
5. Enter a name. For example, enter Now.
6. Select the Return or Enter key.

Create a variable for the milestone

In the following set of procedures, you'll add a Record block to store the milestone date and other milestone-related information.

You could add a Date block instead. However, the Record block resembles the kind of information an API returns to you. In other words, these steps will prepare you to build more complex Flows in the future.

Add a Record block

1. Decide where on the canvas you want to place the Record block and right-click that location.
2. Select Record. If you want to search for the block, enter Record in search.
3. Select Add data blocks and choose String. If you want to search for the block, enter String in search.
4. Enter the string's key and value. For example, if the milestone is for a company, enter company and Postman, respectively.
5. Select Add data blocks and choose Date. If you want to search for the block, enter Date in search.
6. Enter the date's key and value. For example, if the milestone is a company's founded date, enter founded and October 14, 2014, respectively.

Optionally, add more data blocks. For example, to build on the previous steps, you can create a more complex data structure to represent the company's founders. In this case, you could add a list of records, where each item in the list represents a founder, and each record stores the founder's details.

Connect a Select block

1. Hover over the Record block's output port. The pointer changes to a crosshair.
2. Decide where on the canvas you want to place the Select block and drag the port to that location.
3. Select Select. If you want to search for the block, enter Select in search.
4. Select Enter path and choose the Record block's date key. For example, if the milestone is a company's founded date, choose that date.

Connect a Create Variable block

1. Hover over the Select block's output port. The pointer changes to a crosshair.
2. Decide where on the canvas you want to place the Create Variable block and drag the port to that location.
3. Select Create Variable. If you want to search for the block, enter Create Variable in search.
4. Enter the variable's name. For example, if the milestone is a company's founded date, enter date.

Group your blocks

1. Select and hold the Command or Ctrl key.
2. Select the blocks you want to group and select Group selection.
3. Hover over the group's title, select Edit title, and enter a name. For example, enter Postman.
4. Select the Return or Enter key.

Create a variable for milliseconds per year

When you finish this tutorial, you'll calculate the difference between now and the milestone date. However, this calculation will return an answer in milliseconds. For this reason, you must calculate millisecond per year and divide by this value to calculate the difference in years.

In this set of procedures, you'll calculate the average milliseconds per year, which takes leap year into account. However, note that while this is a great approximation, there are more exact methods to calculate the exact value.

Add an Evaluate block

1. Decide where on the canvas you want to place the Evaluate block and right-click that location.

2. Select Evaluate.

3. Add the following to the code editor:

   1000 * 60 * 60 * 24 * 365.25
   

Connect a Create Variable block

1. Hover over the Evaluate block's output port. The pointer changes to a crosshair.
2. Decide where on the canvas you want to place the Create Variable block and drag the port to that location.
3. Select Create Variable.
4. Enter the variable's name. For example, enter millisecondsPerYear.

Group your blocks

1. Select and hold the Command or Ctrl key.
2. Select the blocks you want to group and select Group selection.
3. Hover over the group's title, select Edit title, and enter a name. For example, enter Milliseconds per year.
4. Select the Return or Enter key.

Calculate the years since the milestone

Now that you've created the variables you need to calculate the years since the milestone—now, date, and millisecondsPerYear—you can use them to get an answer.

Add an Evaluate block

Decide where on the canvas you want to place the Evaluate block and right-click that location. Then, select Evaluate.

Get the variables

1. Select Add data blocks and choose Get Variable.
2. Enter the variable's key and choose the variable. For example, if you want to add the "now" variable, enter now and choose now.
3. Repeat these steps for each variable.

Your Evaluate block will reference all the variables you created: now, date, and millisecondsPerYear.

Calculate

All Evaluate blocks default to Flows Query Language (FQL). You'll use FQL to calculate the years since the milestone.

To calculate the value, add the following to the code editor:

$floor(
	(now - date) /
	millisecondsPerYear
)

This calculation takes the difference between now and the milestone date (which is in milliseconds) and divides it by milliseconds per year to get the years since the milestone. The FQL $floor() function removes any decimal values.

Optionally, use TypeScript to calculate this value. If you'd like to try this option, add another Evaluate block, switch to TypeScript (upper-right corner), and use the TypeScript Math.floor() method instead.

Connect an Output block

1. Hover over the Evaluate block's output port. The pointer changes to a crosshair.
2. Decide where on the canvas you want to place the Output block and drag the port to that location.
3. Select Output.

Group your blocks

1. Select and hold the Command or Ctrl key.
2. Select the blocks you want to group and select Group selection.
3. Hover over the group's title, select Edit title, and enter a name. For example, enter Calculate years since milestone.
4. Select the Return or Enter key.

Run the Flow

From the canvas toolbar, select Run.

Congratulations! You calculated the years since a milestone and displayed the result in an Output block.