48 lines
1.6 KiB
JavaScript
48 lines
1.6 KiB
JavaScript
function TablesExtentApi(pgQueryRunner) {
|
|
this.pgQueryRunner = pgQueryRunner;
|
|
}
|
|
|
|
module.exports = TablesExtentApi;
|
|
|
|
/**
|
|
* Given a username and a list of tables it will return the estimated extent in SRID 4326 for all the tables based on
|
|
* the_geom_webmercator (SRID 3857) column.
|
|
*
|
|
* @param {String} username
|
|
* @param {Array} tableNames The named can be schema qualified, so this accepts both `schema_name.table_name` and
|
|
* `table_name` format as valid input
|
|
* @param {Function} callback function(err, result) {Object} result with `west`, `south`, `east`, `north`
|
|
*/
|
|
TablesExtentApi.prototype.getBounds = function (username, tables, callback) {
|
|
var estimatedExtentSQLs = tables.map(function(table) {
|
|
return "ST_EstimatedExtent('" + table.schema_name + "', '" + table.table_name + "', 'the_geom_webmercator')";
|
|
});
|
|
|
|
var query = [
|
|
"WITH ext as (" +
|
|
"SELECT ST_Transform(ST_SetSRID(ST_Extent(ST_Union(ARRAY[",
|
|
estimatedExtentSQLs.join(','),
|
|
"])), 3857), 4326) geom)",
|
|
"SELECT",
|
|
"ST_XMin(geom) west,",
|
|
"ST_YMin(geom) south,",
|
|
"ST_XMax(geom) east,",
|
|
"ST_YMax(geom) north",
|
|
"FROM ext"
|
|
].join(' ');
|
|
|
|
this.pgQueryRunner.run(username, query, function handleBoundsResult (err, rows) {
|
|
if (err) {
|
|
var msg = err.message ? err.message : err;
|
|
return callback(new Error('could not fetch source tables: ' + msg));
|
|
}
|
|
var result = null;
|
|
if (rows.length > 0) {
|
|
result = {
|
|
bounds: rows[0]
|
|
};
|
|
}
|
|
callback(null, result);
|
|
});
|
|
};
|