How to Generate JSON from JSON Schema File in .Net C#?

 Many a times we may have the JSON Schema file describing the JSON content type and its format. Our requirement may be to generate a JSON file from the Schema with the default values for the properties populated from the Schema file. Here we are going to see how this can be done using a simple static utility class in .Net.

Generating Default JSON from JSON Schema file

For this example I have created a Console Application in C# .Net Framework, and in the Program.cs file I have hardcoded the JSON Schema which acts as our input to generate the JSON.


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using Newtonsoft.Json.Linq;
using Newtonsoft.Json.Schema;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace JSONGeneratorFromSchema
{
    public static class JSONGenerator
    {
        public static JToken Generate(JSchema schema)
        {
            JToken token = null;
            switch (schema.Type)
            {
                case JSchemaType.None:
                    break;
                case JSchemaType.Object:
                    {
                        var jObj = new JObject();
                        if (schema.Properties != null)
                        {
                            foreach (var property in schema.Properties)
                            {
                                jObj.Add(Transform(property.Key), Generate(property.Value));
                            }
                        }
                        return jObj;
                    }
                    break;
                case JSchemaType.Array:
                    {
                        var array = new JArray();
                        foreach (var item in schema.Items)
                        {
                            array.Add(Generate(item));
                        }
                        return array;
                    }
                    break;
                case JSchemaType.Integer:
                    {
                        if(schema.Default != null)
                        {
                            var value = new JValue(int.Parse(schema.Default.ToString()));
                            return value;
                        }
                    }
                    break;
                case JSchemaType.Number:
                    {
                        if (schema.Default != null)
                        {
                            var value = new JValue(float.Parse(schema.Default.ToString()));
                            return value;
                        }
                    }
                    break;
                case JSchemaType.String:
                    if (schema.Default != null)
                    {
                        var value = new JValue(schema.Default.ToString());
                        return value;
                    }
                    break;
                case JSchemaType.Boolean:
                    if (schema.Default != null)
                    {
                        var value = new JValue(bool.Parse(schema.Default.ToString()));
                        return value;
                    }
                    break;
                case JSchemaType.Null:
                    return null;
                    break;
                default:
                    break;
            }

            return token;
        }

        private static string Transform(string name)
        {
            return name.Substring(0, 1).ToLower() + name.Substring(1);
        }
    }

    internal class Program
    {
        static void Main(string[] args)
        {
            string schema = @"
{
    ""type"": ""object"",
  ""properties"": 
{
                ""countries"": {
                    ""type"": ""array"",
      ""items"": {
                        ""type"": ""string""
      }
                },
    ""address"": {
                    ""type"": ""object"",
      ""properties"": {
                    ""HouseNo"":{
                            ""type"":""number"",
                            ""default"" : 100
                    },
                    ""Street"":{
                            ""type"":""string"",
                            ""default"" : """"
                    },
                    ""city"":{
                            ""type"":""string"",
                            ""default"" : """"
                    },
                    ""Country"":{
                            ""type"":""string"",
                            ""default"" : """"
                    }
                  }
               }
            },
        }";
            var parsedSchema = JSchema.Parse(schema);
            var jsonDocument = JSONGenerator.Generate(parsedSchema);
            Console.WriteLine(jsonDocument.ToString());
            Console.ReadKey();
        }
    }
}


Above code depicts the code which is used to generate default JSON content from the Schema file. JSONGenerator is  a static class which has an API Generate which takes in the JSchema and gives back the root JObject. It is implemented in a recursive fashion which takes care of the nested JSchema types.

Output obtained as a result of executing the above code is shown below:

JSON generated from JSON Schema with default values

As you can see that the values assigned to the properties are the default ones specified in the JSON Schema file.




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