@loaders.gl/json
Version:
Framework-independent loader for JSON and streaming JSON formats
45 lines (44 loc) • 1.69 kB
JavaScript
// loaders.gl
// SPDX-License-Identifier: MIT
// Copyright (c) vis.gl contributors
// Copyright 2022 Foursquare Labs, Inc.
import { getTableLength, getTableNumCols, getTableRowAsArray } from '@loaders.gl/schema';
/**
* Attempts to identify which column contains geometry
* Currently just returns name (key) of first object-valued column
* @todo look for hints in schema metadata
* @todo look for WKB
*/
export function detectGeometryColumnIndex(table) {
// TODO - look for hints in schema metadata
// look for a column named geometry
const geometryIndex = table.schema?.fields.findIndex((field) => field.name === 'geometry') ?? -1;
if (geometryIndex > -1) {
return geometryIndex;
}
// look at the data
// TODO - this drags in the indices
if (getTableLength(table) > 0) {
const row = getTableRowAsArray(table, 0);
for (let columnIndex = 0; columnIndex < getTableNumCols(table); columnIndex++) {
const value = row?.[columnIndex];
if (value && typeof value === 'object') {
return columnIndex;
}
}
}
throw new Error('Failed to detect geometry column');
}
/**
* Return a row as a property (key/value) object, excluding selected columns
*/
export function getRowPropertyObject(table, row, excludeColumnIndices = []) {
const properties = {};
for (let columnIndex = 0; columnIndex < getTableNumCols(table); ++columnIndex) {
const columnName = table.schema?.fields[columnIndex].name;
if (columnName && !excludeColumnIndices.includes(columnIndex)) {
properties[columnName] = row[columnName];
}
}
return properties;
}