JsonHelper.cs

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using System;
using System.Collections.Generic;
using System.Text;
using Newtonsoft.Json.Linq;
using Newtonsoft.Json;

namespace Avro
{
    class JsonHelper
    {
        public static string GetOptionalString(JToken jtok, string field)
        {
            if (null == jtok) throw new ArgumentNullException("jtok", "jtok cannot be null.");
            if (string.IsNullOrEmpty(field)) throw new ArgumentNullException("field", "field cannot be null.");

            JToken child = jtok[field];
            if (null == child) return null;

            if (child.Type == JTokenType.String)
            {
                string value = child.ToString();
                return value.Trim('\"');
            }
            throw new SchemaParseException("Field " + field + " is not a string");
        }

        public static string GetRequiredString(JToken jtok, string field)
        {
            string value = GetOptionalString(jtok, field);
            if (string.IsNullOrEmpty(value)) throw new SchemaParseException(string.Format("No \"{0}\" JSON field: {1}", field, jtok));
            return value;
        }

        public static int GetRequiredInteger(JToken jtok, string field)
        {
            ensureValidFieldName(field);
            JToken child = jtok[field];
            if (null == child) throw new SchemaParseException(string.Format("No \"{0}\" JSON field: {1}", field, jtok));

            if (child.Type == JTokenType.Integer) return (int) child;
            throw new SchemaParseException("Field " + field + " is not an integer");
        }

        public static bool? GetOptionalBoolean(JToken jtok, string field)
        {
            if (null == jtok) throw new ArgumentNullException("jtok", "jtok cannot be null.");
            if (string.IsNullOrEmpty(field)) throw new ArgumentNullException("field", "field cannot be null.");

            JToken child = jtok[field];
            if (null == child) return null;

            if (child.Type == JTokenType.Boolean)
                return (bool)child;

            throw new SchemaParseException("Field " + field + " is not a boolean");
        }

        internal static void writeIfNotNullOrEmpty(JsonTextWriter writer, string key, string value)
        {
            if (string.IsNullOrEmpty(value)) return;
            writer.WritePropertyName(key);
            writer.WriteValue(value);
        }

        private static void ensureValidFieldName(string name)
        {
            if (string.IsNullOrEmpty(name)) throw new ArgumentNullException("name");
        }
    }
}