ginkgoch-shapefile-reader is a Node.js library to help to read shapefiles from your disk.

View project in Github

shapefile in node.js

A shapefile is a simple, nontopological format for storing the geometric location and attribute information of geographic features. Geographic features in a shapefile can be represented by points, lines, or polygons (areas). The workspace containing shapefiles may also contain dBASE tables, which can store additional attributes that can be joined to a shapefile’s features.

Install

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npm i ginkgoch-shapefile-reader

Test

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npm test

Sample

Loops all records and print the vertices

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async function loopUSStates(callback) {
    const statesShp = await new Shapefile('./tests/data/USStates.shp').open();
    const iterator = await statesShp.iterator();
    let record = undefined;
    while ((record = await iterator.next()) && !record.done) {
        callback(record);
    }
    await statesShp.close();
}

Gets specific record by id

Gets records by id with all fields.

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async function getRecordById(id) {
    const statesShp = await new Shapefile('./tests/data/USStates.shp').open();
    const record = await statesShp.get(0);
    await statesShp.close();
    return record;
}

Gets records by id with none fields. Specify the fields to fetch from DBF to ignore reading unnecessary field values.

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async function getRecordById(id) {
    const statesShp = await new Shapefile('./tests/data/USStates.shp').open();
    const record = await statesShp.get(0, []);
    await statesShp.close();
    return record;
}

Gets matched features one time - Update v1.0.16

If you don’t like to use iteractor way, here is a normal way to get all features back.

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async function getAllRecords() {
    const statesShp = await new Shapefile('./tests/data/USStates.shp').open();
    const record = await statesShp.records();
    await statesShp.close();

    return record;
}

We also provide the filters that you could control the returned value. Here is the default filter structure.

  • from {Number} means the start index of the records. Default value is 0. e.g. { from: 20 } means the returned feature is start from position 20.
  • limit {Number} means the features count includes in the returned features. Default value is Number.MAX_SAVE_INTEGER
  • envelope {Envelope} means the returned features must intersect with the given envelope; default value is undefined, which means no envelope check.
  • fields {Array.<>} means the properties that returned with the features.

Let’s take a look at a demo. Says I want to paging my features. My page size is 10. I want to return all the features from my second page with only properties whose names are RECID and STATE_NAME. Here is the code.

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async function getAllRecords() {
    const statesShp = await new Shapefile('./tests/data/USStates.shp').open();
    const record = await statesShp.records({ from: 10, limit: 10, fields: ['RECID', 'STATE_NAME'] });
    await statesShp.close();

    return record;
}

Reference