Calculating distance by pulling a location from a different table

Hey there! In this step-by-step guide, we'll explore how to calculate the distance between records in different tables using Xano's no-code platform. This functionality can be incredibly useful for building location-based applications, such as finding nearby merchants or services based on a user's location.

Prerequisites

Before we dive in, make sure you have the following:

1. A Xano account set up and a project created.
2. Two tables in your database: one for merchants (or services) and another for users.
3. Each record in both tables should have a location field containing geographical coordinates (e.g., latitude and longitude).

Step 1: Create an API Endpoint

First, let's create a new API endpoint in Xano where we'll handle the distance calculation logic.

1. Navigate to the "APIs" section in your Xano project.
2. Click on the "Create API" button.
3. Give your API a name (e.g., "Calculate Distance") and click "Create."

Step 2: Retrieve User Location

In this step, we'll retrieve the user's location from the database. This will serve as the reference point for calculating the distance to merchants or services.

1. In your API endpoint, add a "Get Record" action.
2. Select the "Users" table from the dropdown.
3. Set the "Where" condition to match the user's ID (e.g., `id = :userId`).
4. Add an input parameter called `userId` to capture the user's ID.

Step 3: Query Merchant Records

Next, we'll query all merchant records and calculate the distance from the user's location for each record.

1. Add a "Query All Records" action and select the "Merchants" table.
2. Click the "Add Eval" button to create a new evaluated field.
3. Name the evaluated field "distance."
4. In the expression field, use the `distance()` function provided by Xano. The syntax is `distance(point1, point2, unit)`, where `point1` and `point2` are the geographical coordinates, and `unit` is the desired unit of measurement (e.g., "km" for kilometers, "mi" for miles).

Your expression should look something like this:

Replace `user.location` with the appropriate field name from the "Get Record" action you performed in Step 2.

1. Click "Save" to apply the changes.

Step 4: Test the API Endpoint

Now that we've set up the API endpoint, let's test it to ensure everything is working correctly.

1. In the API endpoint view, click the "Test" button.
2. Provide a valid `userId` value in the input field.
3. Click "Execute."

The response should display all merchant records, along with the calculated distance from the user's location.

Conclusion

Congratulations! You've successfully learned how to calculate the distance between records in different tables using Xano's no-code platform. This technique can be incredibly powerful for building location-based applications, allowing you to provide users with relevant and contextualized information based on their proximity to various services or merchants.

Remember, Xano is designed to empower both non-technical users and developers alike, enabling you to build and deploy backend services quickly and efficiently without writing a single line of code. So, keep exploring and leveraging Xano's capabilities to bring your ideas to life!