Note: This is an experimental SDK.
Make sure plv8 is installed on your server. Then enable it for your database:
create extension plv8;Now run the script in dist/index.sql and you'll get two SQL functions: extism_create_plugin and extism_call.
Assume you have a table called plugins:
CREATE TABLE public.plugins (
id int4 GENERATED ALWAYS AS IDENTITY( INCREMENT BY 1 MINVALUE 1 MAXVALUE 2147483647 START 1 CACHE 1 NO CYCLE) NOT NULL,
"data" bytea NULL,
"name" varchar NULL,
CONSTRAINT plugins_pk PRIMARY KEY (id)
);Insert a few plugins into the table. And then call:
select extism_call(data, 'count_vowels', 'Hello World!') from plugins where id = 2;Note: this assumes the plugin with id 2 has a function called count_vowels. You can find the plugin here.
If you want more control over your plugin, you can use extism_create_plugin:
-- DROP FUNCTION public.count_vowels_kv(varchar);
CREATE OR REPLACE FUNCTION public.count_vowels_kv(input character varying)
RETURNS character varying
LANGUAGE plv8
AS $function$
const createPlugin = plv8.find_function("extism_create_plugin");
const wasm = plv8.execute("select data from plugins where id = 3")[0];
const opts = {
useWasi: true,
functions: {
"extism:host/user": {
kv_read(cp, offs) {
const key = cp.read(offs).text();
let result = plv8.execute("SELECT value FROM kv WHERE key = $1", [key]);
let value = result.length > 0 ? result[0].value : new Uint8Array([0, 0, 0, 0]);
return cp.store(value);
},
kv_write(cp, kOffs, vOffs) {
const key = cp.read(kOffs).text();
const value = cp.read(vOffs).bytes();
let result = plv8.execute("SELECT value FROM kv WHERE key = $1", [key]);
if (result.length > 0) {
plv8.execute("UPDATE kv SET value = $1 WHERE key = $2", [value, key]);
} else {
plv8.execute("INSERT INTO kv (key, value) VALUES ($1, $2)", [key, value]);
}
}
}
}
};
const plugin = createPlugin(wasm, opts);
return plugin.call("count_vowels", input).text()
$function$
;The above example shows how you can use extism_create_plugin to supply your own host functions to the plugin. You can find th source code for the plugin here.
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