How to build and host (for free!) a mock API that serves data from a PostgreSQL table using RAW
In this example, we are going to build an API that reads data from a PostgreSQL table. This data will then be hosted as a REST API. For this, we are going to be using RAW, a platform to quickly build and host APIs. To follow along, you will need an account, which you can create and use for free here if you don't have one already.
Let's get started!
If you are familiar with RAW and want to deploy this endpoint on your account, click below:
API over PostgreSQL database
- Overview
- Code
Sample usage:
/api/postgresql[?code=<iata_code>]
For instance, to get La Guardia's (LGA) information use:
/api/postgresql?code=LGA
main(code: string = null) =
let
airports = PostgreSQL.InferAndRead(
"raw",
"example",
"airports",
host = "example-psql.raw-labs.com",
username = "**************",
password = "**************"
)
in
Collection.Filter(airports, (x) -> Nullable.IsNull(code) or x.iata_faa == code)
Create a blank API endpoint in RAW
First, we should create a free account:
Once you login to RAW, you should head up to the 'Workspace' section as shown below.
Then, click on 'Add +' to create a new endpoint and choose a new 'Blank Endpoint' as shown below. You could also choose an existing template, but for this example, let's start blank and write the code ourselves.
Write the endpoint code
Now that you have a blank endpoint, let's start writing some code. Before we start, here's an overview of the RAW Workspace.
Now let's follow in steps:
Step 1: Write the code
In RAW, endpoints are written in Snapi, a simple-to-use programming language specifically created specifically for building APIs. You will see this is very simple to create.
Let's copy/paste the following code for our endpoint (see figure, as step '1'):
main(code: string = null) =
let
airports = PostgreSQL.InferAndRead(
"raw", "example", "airports",
host = "example-psql.raw-labs.com",
username = "******",
password = "******"
)
in
Collection.Filter(airports,
x -> Nullable.IsNull(code) or x.iata_faa == code)
// The following test will run if you press the play button.
main("LIS")
Don't worry if you don't follow all the code just yet. This will be explained in detail below.
Step 2: Test the code
Next, let's test the code. Click on the play button (shown in the figure as step '2') and you will have a live preview of the result of calling the last line of the code.
The code will not work as-is because the password is not set. If you instead deploy the endpoint by expanding the box below, an example will be generated automatically that users a demo database we provide, with username/password set.
API over PostgreSQL database
- Overview
- Code
Sample usage:
/api/postgresql[?code=<iata_code>]
For instance, to get La Guardia's (LGA) information use:
/api/postgresql?code=LGA
main(code: string = null) =
let
airports = PostgreSQL.InferAndRead(
"raw",
"example",
"airports",
host = "example-psql.raw-labs.com",
username = "**************",
password = "**************"
)
in
Collection.Filter(airports, (x) -> Nullable.IsNull(code) or x.iata_faa == code)
Step 3: Choose the final URL
You can choose the exact path where your API will be hosted. This is shown in the figure as step '3'.
Step 4: Edit the metadata
Optionally, you can edit the metadata metadata (shown in the figure as step '4'). The metadata is important since RAW includes a built-in API Catalog that helps you and your users find API endpoints later.
Step 5: Deploy the endpoint live!
We are almost done. Now click to deploy your endpoint (shown in the figure as step '5').
Congratulations, your API is now published! It will be served right away and visible in the API Catalog as well.
How does the code work?
Let's look closer at how the Snapi code works!
main(code: string = null) =
let
airports = PostgreSQL.InferAndRead(
"raw", "example", "airports",
host = "example-psql.raw-labs.com",
username = "******",
password = "******"
)
in
Collection.Filter(airports,
x -> Nullable.IsNull(code) or x.iata_faa == code)
// The following test will run if you press the play button.
main("LIS")
- Line 1 defines the
main
method. Its arguments will become query parameters in the URL call. These arguments all have default values (null
to be precise), which means they are optional arguments. The valuenull
(i.e. not defined) will be handled later during the filtering operation. In this case,t he only argument is the IATA airport code. - Lines 3-8 defines the data source. In this case, it is a PostgreSQL table. Credentials are hidden and can be specified using "Secrets".
- Line 10 applies a filter. This will filter the PostgreSQL table so that we are left only with the rows whose values match the arguments (if defined).
- The filter condition is defined in Line 11. The pattern
Nullable.IsNull(code) or x.iata_faa == code
is used to apply the filter on IATA code only if thecode
value was defined by the user. TheNullable.IsNull(code)
will return true if the value is null. Otherwise, if the value is not null it means the user passed a code argument to filter on; in that case we check thatx.iata_faa == code
, i.e. the airport code info in the table matches the code passed by the user. - Line 13 defines the test to run when the play button is pressed.
Never store sensitive information as clear text in the code.
Instead use secrets, which are key/value pairs that are stored securely outside of the source code.
Secrets can be accessed using the built-in function Environment.Secret
.
Let's improve this API!
Now that you understand the basic concepts, there's many improvements that can be done. Below is a list of pointers:
- To learn how to manage credentials safely, read this guide.
- To secure the endpoint, read this guide.
- To improve performance with caching, read this guide.
- Learn how to invite users.
- To create API keys, read this guide.
- If you prefer, paid plans have access to GitHub integration, which allow teams to collaboratively build code together, write test suites, and provides a complete CI/CD flow.
What's next!
Take a look at other examples, or join us on Discord to learn more!
Ready to try it out?
Register for free and start building today!Otherwise, if you have questions/comments, join us on Discord!