Read header file of .json and determine to which format it belongs to

Question

Hi,

Extension .json  format suits  to four formats: GeoJson, EsriJson, GeoJsonSeq, TopoJson.

How check the headers of these file and to determine to which format they  belong to ?

{ “.json”, “GeoJson” }, { “.json”, “EsriJson” }, { “.json”, “GeoJsonSeq” }, { “.json”, “TopoJson” },

 Please provide a ffull sample code for this operation in .NET 9 - C#.

I attached the sample files.

 

Thanks,

Dani

Answer 1

To determine the specific format of a .json file (such as GeoJson, EsriJson, GeoJsonSeq, or TopoJson) based on its header, you can read the file's content and check for specific characteristics or keys that are unique to each format. Below is a sample code in C# that demonstrates how to perform this operation:

using System;
using System.IO;
using Newtonsoft.Json.Linq;

class Program
{
    static void Main(string[] args)
    {
        string filePath = "path_to_your_file.json"; // Replace with your file path
        string format = DetermineJsonFormat(filePath);
        Console.WriteLine($"The format of the file is: {format}");
    }

    static string DetermineJsonFormat(string filePath)
    {
        if (!File.Exists(filePath))
        {
            throw new FileNotFoundException("File not found.", filePath);
        }

        string jsonContent = File.ReadAllText(filePath);
        JObject jsonObject = JObject.Parse(jsonContent);

        // Check for GeoJson
        if (jsonObject.ContainsKey("type") && jsonObject["type"]?.ToString() == "FeatureCollection")
        {
            return "GeoJson";
        }

        // Check for EsriJson
        if (jsonObject.ContainsKey("spatialReference") && jsonObject.ContainsKey("features"))
        {
            return "EsriJson";
        }

        // Check for GeoJsonSeq
        if (jsonObject.Type == JTokenType.Array)
        {
            return "GeoJsonSeq";
        }

        // Check for TopoJson
        if (jsonObject.ContainsKey("type") && jsonObject["type"]?.ToString() == "Topology")
        {
            return "TopoJson";
        }

        return "Unknown format";
    }
}

Explanation:

1. File Reading: The code reads the content of the specified JSON file.
2. JSON Parsing: It uses Newtonsoft.Json to parse the JSON content into a JObject.
3. Format Checking: The code checks for specific keys and values that are characteristic of each format:
   • GeoJson: Looks for a type key with the value FeatureCollection.
   • EsriJson: Checks for spatialReference and features keys.
   • GeoJsonSeq: Determines if the JSON is an array.
   • TopoJson: Looks for a type key with the value Topology.
4. Output: It prints the determined format.

Make sure to install the Newtonsoft.Json package via NuGet to use this code.

---

References:

• GeoJSON Module Examples
• Data formats supported for ingestion

Answer 2

I'm adding the json files, I added .txt to extensions, since there is a limitation to load .json files here.