geojson-validation

GeoJSON-Validation

A GeoJSON Validation Library
Check JSON objects to see whether or not they are valid GeoJSON. Validation is based off of the GeoJSON Format Specification revision 1.0

• Installation
• Usage
• Cli usage
• Api
• Testing
• Cavets

Installation

npm install geojson-validation

usage

var GJV = require("geojson-validation");

var validFeatureCollection = {
    "type": "FeatureCollection",
    "features": [
        {
            "type": "Feature",
            "geometry": {"type": "Point", "coordinates": [102.0, 0.5]},
            "properties": {"prop0": "value0"}
        },
        {
            "type": "Feature",
            "geometry": {
                "type": "LineString",
                "coordinates": [
                    [102.0, 0.0], [103.0, 1.0], [104.0, 0.0], [105.0, 1.0]
                ]
            },
            "properties": {
                "prop0": "value0",
                "prop1": 0.0
            }
        }
    ]
};

//simple test
if(GJV.valid(validFeatureCollection)){
    console.log("this is valid GeoJSON!");
}

var invalidFeature =  {
    "type": "feature",
    "geometry": {
        "type": "LineString",
        "coordinates": [
            [102.0, 0.0], [103.0, 1.0], [104.0, 0.0], [105.0, 1.0]
        ]
    },
    "properties": {
        "prop0": "value0",
        "prop1": 0.0
    }
};

//test to see if `invalidFeature` is valid
GJV.isFeature(invalidFeature, function(valid, errs){
    //log the errors
    if(!valid){
       console.log(errs);
    }
});

CLI usage

first install gobally
npm install geojson-validation -g
Then you can use gjv to validate file such as
gjv file1 file2..
Or you can stream files to it cat file | gjv
gjv will either return a list of error or a valid if the files are indeed valid.

API

All Function return a boolean and take a JSON object that will be evalatued to see if it is a GeoJSON object, with the exception of define.

Arguments

• geoJSON - a JSON object that is tested to see if it is a valid GeoJSON object
• callback(boolean, errors) - boolean is whether or not the object is valid. errors is an array of validation errors for an invalid JSON object.

valid(geoJSON, callback)

Alias: isGeoJSONObject
Checks if an object is a GeoJSON Object.

---

isGeoJSONObject(geoJSON, callback)

Checks if an object is a GeoJSON Object.

---

isGeometryObject(geoJSON, callback)

Checks if an object is a Geometry Object

---

isPosition(array, callback)

Checks if an array is a Position

---

isPoint(geoJSON, callback)

Checks if an object is a Point

---

isMultiPointCoor(array, callback)

Checks if an array can be interperted as coordinates for a MultiPoint

---

isMultiPoint(geoJSON, callback)

Checks if an object is a MultiPoint

---

isLineStringCoor(array, callback)

Checks if an array can be interperted as coordinates for a LineString

---

isLineString(geoJSON, callback)

Checks if an object is a Line String

---

isMultiLineStringCoor(array, callback)

Checks if an array can be interperted as coordinates for a MultiLineString

---

isMultiLineString(geoJSON, callback)

Checks if an object is a MultiLine String

---

isPolygonCoor(array, callback)

Checks an array can be interperted as coordinates for a Polygon

---

isPolygon(geoJSON, callback)

Checks if an object is a Polygon

---

isMultiPolygonCoor(array, callback)

Checks if an array can be interperted as coordinates for a MultiPolygon

---

isMultiPolygon(geoJSON, callback)

Checks if an object is a MultiPolygon

---

isGeometryCollection(geoJSON, callback)

Checks if an object is a Geometry Collection

---

isFeature(geoJSON, callback)

Checks if an object is a Feature Object

---

isFeatureCollection(geoJSON, callback)

Checks if an object is a Feature Collection Object

---

isBbox(array, callback)

Checks if an object is a Bounding Box

---

Define(type, function)

Define a Custom Validation for the give type. type can be "Feature", "FeatureCollection", "Point", "MultiPoint", "LineString", "MultiLineString", "Polygon", "MultiPolygon", "GeometryCollection", "Bbox", "Position", "GeoJSON" or "GeometryObject".

The function is passed the object being validated and should return a string or an array of strings representing errors. If there are no errors then the function should not return anything or an empty array. See the example for more.

---

Define Example

Shout out to @VitoLau for the code for this example.

GJV = require("geojson-validation");

GJV.define("Position", function(position){
    //the postion must be valid point on the earth, x between -180 and 180
    errors = [];
    if(position[0] < -180 || position[0] > 180){
        errors.push("the x must be between -180 and 180");
    }
    if(position[1] < -90 || position[1] > 90){
        errors.push("the y must be between -90 and 90");
    }
    return errors;

});

gj = {type: "Point", coordinates: [-200,3]};
//returns false
GJV.isPoint(gj);

Testing

To run tests npm test
Test use mocha

Cavets

• Does not check ordering of Bouding Box coordinates
• Does not check Coordinate Reference System Objects
• Does not check order of rings for polygons with multiple rings