This content originally appeared on HackerNoon and was authored by Nicolas Frankel
I spoke at Swiss PgDay in Switzerland in late June. The talk was about how to create a no-code API with the famous PostgreSQL database, the related PostgREST, and Apache APISIX, of course. I already wrote about the idea in a previous post. However, I wanted to improve it, if only slightly.
\
PostgREST offers a powerful SELECT mechanism. To list all entities with a column equal to a value, you need the following command:
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curl /products?id=eq.1
idis the columneq.1corresponds to theWHEREclause
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In this case, the generated query is SELECT * FROM products WHERE id=1.
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The query syntax is powerful and allows you to express complex queries. However, as an API designer, I want to avoid exposing users to this complexity. For example, a regular API can manage entities by their ID, e.g., /products/1. In turn, you'd expect PostgREST to be able to do the same with primary keys. Unfortunately, it doesn't treat primary keys any differently than regular columns. Apache APISIX to the rescue.
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One of APISIX's best features is to rewrite requests, i.e., exposing /products/1 and forwarding /products?id=eq.1 to PostgREST. Let's do it.
\ First, we need to capture the ID of the path parameter. For this, we need to replace the regular radix tree router with the radix tree with a parameter router.
\
apisix:
router:
http: radixtree_uri_with_parameter
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The next step is to rewrite the URL. We use the proxy-rewrite plugin for this on a /products/:id route. Unfortunately, using the :id parameter above in the regular expression is impossible. We need to copy it to a place that is accessible. To do that, before the rewriting, we can leverage the serverless-pre-function. With the plugin, you can write Lua code directly. It's an excellent alternative to a full-fledged plugin for short, straightforward snippets.
\ Here's the configuration:
\
curl -i http://localhost:9180/apisix/admin/plugin_configs/1 -X PUT -d '
{
"plugins": {
"serverless-pre-function": {
"phase": "rewrite",
"functions" : [
"return function(_, ctx)
ctx.var.product_id = ctx.curr_req_matched.id; #1
end"
]
},
"proxy-rewrite": {
"uri": "/products?id=eq.$product_id" #2
}
}
}'
- Copy the captured
idvariable to a place accessible to other plugins later on - Use it!
\ Thanks to my colleague Zeping for pointing out the solution to me!
\
You can expose the /products/1 REST-friendly URL and let APISIX rewrite it for PostgREST.
Conclusion
In this post, I've described using the proxy-rewrite plugin with a path variable. You can reuse the same technique with multiple variables. Keep also in mind that the serverless plugin is a hidden jewel; it can help you with small Lua snippets before moving to a full-fledged plugin.
To go further:
\
This content originally appeared on HackerNoon and was authored by Nicolas Frankel
Nicolas Frankel | Sciencx (2024-07-19T13:11:20+00:00) Improving No-Code APIs with PostgreSQL, PostgREST, and Apache APISIX. Retrieved from https://www.scien.cx/2024/07/19/improving-no-code-apis-with-postgresql-postgrest-and-apache-apisix/
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