63 lines
2.1 KiB
PL/PgSQL
63 lines
2.1 KiB
PL/PgSQL
-- encode straeto API params into the query string by the graphql API.
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-- yes, javascript in the database: the lazy way.
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CREATE OR REPLACE FUNCTION encode_straeto_querystring(obj jsonb) RETURNS text
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LANGUAGE plv8 STRICT IMMUTABLE AS $$
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return Object.keys(obj).map(function(variableName) {
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const variableValue = obj[variableName];
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if (typeof variableValue == 'object') {
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return encodeURIComponent(variableName) + '=' + encodeURIComponent(JSON.stringify(variableValue));
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} else {
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return encodeURIComponent(variableName) + '=' + encodeURIComponent(variableValue);
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}
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}).join('&');
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$$;
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CREATE OR REPLACE FUNCTION create_straeto_parameters(bus_routes text[]) RETURNS jsonb
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LANGUAGE plpgsql AS $$
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DECLARE query_params jsonb;
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BEGIN
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-- This is the unencoded GraphQL request payload.
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query_params := '{
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"operationName": "BusLocationByRoute",
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"variables": { "trips":[], "routes": [] },
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"extensions": {
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"persistedQuery": {
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"version": 1,
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"sha256Hash": "8f9ee84171961f8a3b9a9d1a7b2a7ac49e7e122e1ba1727e75cfe3a94ff3edb8"
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}
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}
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}'::jsonb;
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-- Add requested bus routes to the `routes` GraphQL variable.
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SELECT INTO query_params
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jsonb_set(query_params, '{variables, routes}', array_to_json(bus_routes)::jsonb);
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RETURN query_params;
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END
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$$;
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-- Builds the full request URL to download bus positions of the given
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-- route numbers.
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CREATE OR REPLACE FUNCTION build_api_url(bus_routes text[]) RETURNS text LANGUAGE sql AS $$
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SELECT concat(
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'https://straeto.is/graphql?',
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encode_straeto_querystring(create_straeto_parameters(bus_routes))
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);
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$$;
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-- Called by a scheduled job to request data on a timer. A trigger
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-- handles insertion of the response after record initially inserted.
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CREATE TABLE IF NOT EXISTS raw_bus_position_requests(
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request_id int,
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created TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT NOW()
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);
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CREATE OR REPLACE FUNCTION gather_bus_data()
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RETURNS void LANGUAGE sql
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as $$
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INSERT INTO raw_bus_position_requests (request_id) SELECT
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net.http_get(
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url := build_api_url(array['1', '2', '3']),
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headers := '{"Content-Type": "application/json"}'::jsonb
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);
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$$;
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