Add logical PostGIS operators support to the plugin

They include the official logical operators (see https://postgis.net/docs/reference.html, section 8.8) and other operators returning a boolean value such as spatial relationships functions (e.g. ST_Disjoint, see section 8.9).

An experimental extension was made in the fork https://github.com/jepetko/postgraphile-plugin-connection-filter/commits/master incl. test setup of the dedicated “postgis” schema alongside the already existing “p” schema.

Example (see https://github.com/jepetko/postgraphile-plugin-connection-filter/blob/master/__tests__/fixtures/postgis-queries/postgis-connections-filter.graphql):

query {
  overlapping: allFilterables(filter: { theGeom: { overlapsBB: "LINESTRING(1 2, 4 6)" } }) { ...filterableConnection }
  disjointG: allFilterables(filter: { theGeom: { disjointsG: "LINESTRING(0 5, 4 6)" } }) { ...filterableConnection }
  intersectsG: allFilterables(filter: { theGeom: { intersectsG: "LINESTRING(-1 1, 3 1)" } }) { ...filterableConnection }
}

fragment filterableConnection on FilterablesConnection {
  pageInfo {
    ...
  }
  totalCount
  edges {
    cursor
    node {
      id
      theGeom
    }
  }
}

[mattbretl]

FYI, I just published this: https://github.com/mattbretl/postgraphile-plugin-connection-filter-postgis

Note: @graphile/postgis only supports SRID 4326 at the moment, so if you need to use other SRIDs, you still need a custom plugin like the examples above.

[mattbretl]

Sorry for the delay… this fell off my todo list. We still need a PostGIS plugin that does the upfront introspection work necessary to expose the right operators per geometry/geography type.

The approach you shared using allowedFieldTypes: ['String'] worked through beta.27, but beta.28 checks whether the field is a true string type (text, varchar, etc.) before exposing filter operators. As a result, your code won’t work with beta.28. If you (or anyone else) still needs this functionality, the fix is to register a GraphQL input type for the PostGIS geometry type. Here’s a full example based on the code you provided:

create extension postgis;

create schema app_public;

create table app_public.foo (
  id serial primary key,
  geom geometry(point,3857)
);

insert into app_public.foo (geom) values
  ('SRID=3857;POINT(1 1)'::geometry),
  ('SRID=3857;POINT(2 2)'::geometry),
  ('SRID=3857;POINT(3 3)'::geometry);

// PgConnectionArgFilterPostgisOperatorsPlugin.js
module.exports = function PgConnectionArgFilterPostgisOperatorsPlugin(builder) {
  // Register geometry type
  builder.hook("build", build => {
    const {
      graphql: { GraphQLScalarType, Kind },
      pgIntrospectionResultsByKind: introspectionResultsByKind,
      pgRegisterGqlTypeByTypeId,
      pgRegisterGqlInputTypeByTypeId
    } = build;
    const postgisExtension = introspectionResultsByKind.extension.find(
      e => e.name === "postgis"
    );
    const postgisGeometryType = introspectionResultsByKind.type.find(
      t =>
        t.name === "geometry" && t.namespaceId === postgisExtension.namespaceId
    );

    const GeometryType = new GraphQLScalarType({
      name: "Geometry",
      description:
        "Geometry property of a GeoJSON object; coordinates must be in EPSG:3857.",
      serialize: value => String(value),
      parseValue: value => String(value),
      parseLiteral: ast => {
        if (ast.kind !== Kind.STRING) {
          throw new Error("Can only parse string values");
        }
        return ast.value;
      }
    });

    pgRegisterGqlTypeByTypeId(postgisGeometryType.id, () => GeometryType);
    pgRegisterGqlInputTypeByTypeId(postgisGeometryType.id, () => GeometryType);

    return build;
  });

  // Add operators
  builder.hook("build", (input, build) => {
    const { addConnectionFilterOperator, pgSql: sql } = build;
    addConnectionFilterOperator(
      "bboxIntersects2D",
      `Returns TRUE if A's 2D bounding box intersects B's 2D bounding box.`,
      fieldInputType => fieldInputType,
      (identifier, val) => {
        return sql.query`CASE WHEN ST_SRID(${identifier}) <> 3857
          THEN ${identifier} && ST_Transform(ST_SetSRID(ST_GeomFromGeoJSON(${val}), 3857), ST_SRID(${identifier}))
          ELSE ${identifier} && ST_GeomFromGeoJSON(${val})
          END`;
      },
      {
        allowedFieldTypes: ["Geometry"]
      }
    );

    return input;
  });
};

const express = require("express");
const { postgraphile } = require("postgraphile");
const PgConnectionFilterPlugin = require("postgraphile-plugin-connection-filter");
const PgConnectionFilterPostgisPlugin = require("./PgConnectionArgFilterPostgisOperatorsPlugin.js");

const app = express();

app.use(
  postgraphile(process.env.DATABASE_URL, "app_public", {
    appendPlugins: [PgConnectionFilterPlugin, PgConnectionFilterPostgisPlugin],
    graphiql: true
  })
);

app.listen(5000);

{
  allFoos(filter: {
    geom: {
      bboxIntersects2D: "{\"type\":\"LineString\",\"coordinates\":[[2,2],[4,5]]}"
    }
  }) {
    nodes {
      id
    }
  }
}

{
  "data": {
    "allFoos": {
      "nodes": [
        {
          "id": 2
        },
        {
          "id": 3
        }
      ]
    }
  }
}

Hope that helps.