46 lines
1.6 KiB
TypeScript
46 lines
1.6 KiB
TypeScript
import { MigrationInterface, QueryRunner } from 'typeorm';
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export class AddDistanceFunction1648669551959 implements MigrationInterface {
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public async up(queryRunner: QueryRunner): Promise<void> {
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// From https://stackoverflow.com/questions/61135374/postgresql-calculate-distance-between-two-points-without-using-postgis
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await queryRunner.query(`
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CREATE OR REPLACE FUNCTION calculate_distance(lat1 float, lon1 float, lat2 float, lon2 float, units varchar)
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RETURNS float AS $dist$
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DECLARE
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dist float = 0;
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radlat1 float;
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radlat2 float;
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theta float;
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radtheta float;
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BEGIN
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IF lat1 = lat2 OR lon1 = lon2
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THEN RETURN dist;
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ELSE
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radlat1 = pi() * lat1 / 180;
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radlat2 = pi() * lat2 / 180;
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theta = lon1 - lon2;
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radtheta = pi() * theta / 180;
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dist = sin(radlat1) * sin(radlat2) + cos(radlat1) * cos(radlat2) * cos(radtheta);
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IF dist > 1 THEN dist = 1; END IF;
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dist = acos(dist);
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dist = dist * 180 / pi();
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dist = dist * 60 * 1.1515;
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IF units = 'K' THEN dist = dist * 1.609344; END IF;
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IF units = 'N' THEN dist = dist * 0.8684; END IF;
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RETURN dist;
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END IF;
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END;
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$dist$ LANGUAGE plpgsql;`);
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}
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public async down(queryRunner: QueryRunner): Promise<void> {
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await queryRunner.query(
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`DROP FUNCTION IF EXISTS calculate_distance(lat1 float, lon1 float, lat2 float, lon2 float, units varchar);`,
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);
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}
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}
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