PgGeometryPlugin.ts

import type { PgCodec } from '@dataplan/pg';
import { EXPORTABLE } from 'graphile-build';
import { sql } from 'pg-sql2';
import { Geometry } from 'wkx';

interface State {
  geometryCodec: PgCodec<string, any, any, any, undefined, any, any>;
}

declare global {
  namespace GraphileConfig {
    interface Plugins {
      PgGeometryPlugin: true;
    }
  }
}

export const PgGeometryPlugin: GraphileConfig.Plugin = {
  name: 'PgGeometryPlugin',

  gather: {
    initialState(): State {
      const geometryCodec: PgCodec<string, any, any, any, undefined, any, any> = EXPORTABLE(
        (sql) => ({
          name: 'geometry',
          sqlType: sql`geometry`,
          toPg(str) {
            return str;
          },
          fromPg(str) {
            return Geometry.parse(Buffer.from(str, 'hex')).toGeoJSON();
          },
          executor: null,
          attributes: undefined,
        }),
        [sql]
      );

      return { geometryCodec };
    },
    hooks: {
      async pgCodecs_findPgCodec(info, event) {
        // If another plugin has already supplied a codec; skip
        if (event.pgCodec) return;

        const { serviceName, pgType } = event;

        const geometryExt = await info.helpers.pgIntrospection.getExtensionByName(
          serviceName,
          'postgis'
        );

        if (!geometryExt || pgType.typnamespace !== geometryExt.extnamespace) {
          return;
        }

        if (pgType.typname === 'geometry') {
          event.pgCodec = info.state.geometryCodec;
        }
      },
    },
  },

  schema: {
    hooks: {
      init(_, build) {
        const codec = build.input.pgRegistry.pgCodecs.geometry;

        if (codec) {
          const geometryTypeName = build.inflection.builtin('Geometry');
          build.registerScalarType(
            geometryTypeName,
            { pgCodec: codec },
            () => ({
              description:
                'Represents an `geometry` type https://postgis.net/workshops/postgis-intro/geometries.html',
            }),
            'Adding "Geometry" scalar type from PgGeometryPlugin.'
          );
          build.setGraphQLTypeForPgCodec(codec, 'output', geometryTypeName);
          build.setGraphQLTypeForPgCodec(codec, 'input', geometryTypeName);
        }
        return _;
      },
    },
  },
};