postgis/lib/mvt.js

A Node.js class for interacting with PostGIS-enabled PostgreSQL databases.

module.exports = function (table, x, y, z, columns, id_column, geom_column, filter) {
    return `
      WITH mvtgeom as (
        SELECT
          ST_AsMVTGeom (
            ST_Transform(${geom_column}, 3857),
            ST_TileEnvelope(${z}, ${x}, ${y})
          ) as geom
          ${columns ? `, ${columns}` : ''}
          ${id_column ? `, ${id_column}` : ''}
        FROM
          ${table},
          (SELECT ST_SRID(${geom_column}) AS srid FROM ${table} WHERE ${geom_column} IS NOT NULL LIMIT 1) a
        WHERE
          ST_Intersects(
            ${geom_column},
            ST_Transform(
              ST_TileEnvelope(${z}, ${x}, ${y}),
              srid
            )
          )
  
          ${filter ? ` AND ${filter}` : ''}
      )
      SELECT ST_AsMVT(mvtgeom.*, '${table}', 4096, 'geom' ${id_column ? `, '${id_column}'` : ''
        }) AS mvt from mvtgeom;
    `
}