Analysieren von JSON mit Json.net

Ich versuche, JSON mithilfe der JSon.Net-Bibliothek zu analysieren. Die Dokumentation wirkt etwas spärlich und ich bin verwirrt, wie ich das erreichen soll, was ich brauche. Hier ist das Format für den JSON, den ich analysieren muss.

{
    "displayFieldName" : "OBJECT_NAME", 
    "fieldAliases" : {
        "OBJECT_NAME" : "OBJECT_NAME", 
        "OBJECT_TYPE" : "OBJECT_TYPE"
    }, 
    "positionType" : "point", 
    "reference" : {
        "id" : 1111
    }, 
    "objects" : [ {
        "attributes" : {
            "OBJECT_NAME" : "test name", 
            "OBJECT_TYPE" : "test type"
        }, 
        "position" : {
            "x" : 5, 
            "y" : 7
        }
    } ]
}

Die einzigen Daten, die ich wirklich brauche, sind die Inhalte im Objektarray. Kann ich das mit so etwas wie dem JSonTextReader analysieren und einfach die gewünschten Dinge herausziehen, wie OBJECT_TYPE und die x- und y-Position? Ich kann anscheinend nicht so JSonTextReaderarbeiten, wie ich es möchte, und ich finde wenig bis gar keine Anwendungsbeispiele dafür.

Es scheint, als wäre es ideal, zuerst zu serialisieren und dann LINQ mit meinem Objekt zu verwenden. In jedem Beispiel, das ich finde, wird zuerst das Serialisieren von JSON erörtert, aber ich bin mir nicht sicher, wie ich ein Objekt für diese Struktur erstellen würde. Insbesondere das Objektarray, das so etwas wie eine Liste von Paaren von Attribut- und Positionsobjekten sein müsste. Ich habe keine Ahnung, wie ich mein Objekt codieren würde, damit JSon.Net weiß, wie man das serialisiert.

Ich dachte, ich könnte meinen eigenen einfachen Parser schreiben, um einfach alles, was ich brauche, in ein von mir erstelltes Attributobjekt zu ziehen, aber ich habe wenig Glück.

Hoffentlich macht das alles Sinn, irgendwelche Ideen?

Ich weiß nicht , über JSON.NET, aber es funktioniert gut mit JavaScriptSerializeraus System.Web.Extensions.dll(.NET 3.5 SP1):

using System.Collections.Generic;
using System.Web.Script.Serialization;
public class NameTypePair
{
    public string OBJECT_NAME { get; set; }
    public string OBJECT_TYPE { get; set; }
}
public enum PositionType { none, point }
public class Ref
{
    public int id { get; set; }
}
public class SubObject
{
    public NameTypePair attributes { get; set; }
    public Position position { get; set; }
}
public class Position
{
    public int x { get; set; }
    public int y { get; set; }
}
public class Foo
{
    public Foo() { objects = new List<SubObject>(); }
    public string displayFieldName { get; set; }
    public NameTypePair fieldAliases { get; set; }
    public PositionType positionType { get; set; }
    public Ref reference { get; set; }
    public List<SubObject> objects { get; set; }
}
static class Program
{

    const string json = @"{
  ""displayFieldName"" : ""OBJECT_NAME"", 
  ""fieldAliases"" : {
    ""OBJECT_NAME"" : ""OBJECT_NAME"", 
    ""OBJECT_TYPE"" : ""OBJECT_TYPE""
  }, 
  ""positionType"" : ""point"", 
  ""reference"" : {
    ""id"" : 1111
  }, 
  ""objects"" : [
    {
      ""attributes"" : {
        ""OBJECT_NAME"" : ""test name"", 
        ""OBJECT_TYPE"" : ""test type""
      }, 
      ""position"" : 
      {
        ""x"" : 5, 
        ""y"" : 7
      }
    }
  ]
}";


    static void Main()
    {
        JavaScriptSerializer ser = new JavaScriptSerializer();
        Foo foo = ser.Deserialize<Foo>(json);
    }


}

Bearbeiten:

Json.NET arbeitet mit demselben JSON und denselben Klassen.

Foo foo = JsonConvert.DeserializeObject<Foo>(json);

Link: Serialisieren und Deserialisieren von JSON mit Json.NET

Edit: Danke Marc, lies das Thema Struktur gegen Klasse nach und du hast Recht, danke!

Ich neige dazu, die folgende Methode zu verwenden, um das zu tun, was Sie beschreiben, mit einer statischen Methode von JSon.Net:

MyObject deserializedObject = JsonConvert.DeserializeObject<MyObject>(json);

Link: Serialisieren und Deserialisieren von JSON mit Json.NET

Darf ich für die Objektliste vorschlagen, generische Listen zu verwenden, die aus Ihrer eigenen kleinen Klasse mit attributesund positionKlasse erstellt wurden. Sie können die PointStruktur in System.Drawing( System.Drawing.Pointoder System.Drawing.PointFfür Gleitkommazahlen) für Ihre X und Y verwenden.

Nach der Objekterstellung ist es viel einfacher, die Daten zu erhalten, nach denen Sie suchen, als die Textanalyse, die Sie sonst betrachten.

(Diese Frage tauchte in einem Suchmaschinenergebnis häufig auf, aber ich habe einen anderen Ansatz gewählt. Hinzufügen einer Antwort auf diese alte Frage, falls andere Personen mit ähnlichen Fragen dies lesen)

Sie können dies mit Json.Net lösen und eine Erweiterungsmethode erstellen, um die Elemente zu verarbeiten, die Sie schleifen möchten:

public static Tuple<string, int, int> ToTuple(this JToken token)
{
    var type = token["attributes"]["OBJECT_TYPE"].ToString();
    var x = token["position"]["x"].Value<int>();
    var y = token["position"]["y"].Value<int>();
    return new Tuple<string, int, int>(type, x, y);
}

Und dann greifen Sie wie folgt auf die Daten zu: (Szenario: Schreiben auf die Konsole):

var tuples = JObject.Parse(myJsonString)["objects"].Select(item => item.ToTuple()).ToList();
tuples.ForEach(t => Console.WriteLine("{0}: ({1},{2})", t.Item1, t.Item2, t.Item3));

/*
     * This method takes in JSON in the form returned by javascript's
     * JSON.stringify(Object) and returns a string->string dictionary.
     * This method may be of use when the format of the json is unknown.
     * You can modify the delimiters, etc pretty easily in the source
     * (sorry I didn't abstract it--I have a very specific use).
     */ 
    public static Dictionary<string, string> jsonParse(string rawjson)
    {
        Dictionary<string, string> outdict = new Dictionary<string, string>();
        StringBuilder keybufferbuilder = new StringBuilder();
        StringBuilder valuebufferbuilder = new StringBuilder();
        StringReader bufferreader = new StringReader(rawjson);

        int s = 0;
        bool reading = false;
        bool inside_string = false;
        bool reading_value = false;
        //break at end (returns -1)
        while (s >= 0)
        {
            s = bufferreader.Read();
            //opening of json
            if (!reading)
            {
                if ((char)s == '{' && !inside_string && !reading) reading = true;
                continue;
            }
            else
            {
                //if we find a quote and we are not yet inside a string, advance and get inside
                if (!inside_string)
                {
                    //read past the quote
                    if ((char)s == '\"') inside_string = true;
                    continue;
                }
                if (inside_string)
                {
                    //if we reached the end of the string
                    if ((char)s == '\"')
                    {
                        inside_string = false;
                        s = bufferreader.Read(); //advance pointer
                        if ((char)s == ':')
                        {
                            reading_value = true;
                            continue;
                        }
                        if (reading_value && (char)s == ',')
                        {
                            //we know we just ended the line, so put itin our dictionary
                            if (!outdict.ContainsKey(keybufferbuilder.ToString())) outdict.Add(keybufferbuilder.ToString(), valuebufferbuilder.ToString());
                            //and clear the buffers
                            keybufferbuilder.Clear();
                            valuebufferbuilder.Clear();
                            reading_value = false;
                        }
                        if (reading_value && (char)s == '}')
                        {
                            //we know we just ended the line, so put itin our dictionary
                            if (!outdict.ContainsKey(keybufferbuilder.ToString())) outdict.Add(keybufferbuilder.ToString(), valuebufferbuilder.ToString());
                            //and clear the buffers
                            keybufferbuilder.Clear();
                            valuebufferbuilder.Clear();
                            reading_value = false;
                            reading = false;
                            break;
                        }
                    }
                    else
                    {
                        if (reading_value)
                        {
                            valuebufferbuilder.Append((char)s);
                            continue;
                        }
                        else
                        {
                            keybufferbuilder.Append((char)s);
                            continue;
                        }
                    }
                }
                else
                {
                    switch ((char)s)
                    {
                        case ':':
                            reading_value = true;
                            break;
                        default:
                            if (reading_value)
                            {
                                valuebufferbuilder.Append((char)s);
                            }
                            else
                            {
                                keybufferbuilder.Append((char)s);
                            }
                            break;
                    }
                }
            }
        }
        return outdict;
    }

Sie verwenden die JSONKlasse und rufen dann die GetData()Funktion auf.

/// <summary>
/// This class encodes and decodes JSON strings.
/// Spec. details, see http://www.json.org/
///
/// JSON uses Arrays and Objects. These correspond here to the datatypes ArrayList and Hashtable.
/// All numbers are parsed to doubles.
/// </summary>
    using System;
    using System.Collections;
    using System.Globalization;
    using System.Text;

public class JSON
{
    public const int TOKEN_NONE = 0;
    public const int TOKEN_CURLY_OPEN = 1;
    public const int TOKEN_CURLY_CLOSE = 2;
    public const int TOKEN_SQUARED_OPEN = 3;
    public const int TOKEN_SQUARED_CLOSE = 4;
    public const int TOKEN_COLON = 5;
    public const int TOKEN_COMMA = 6;
    public const int TOKEN_STRING = 7;
    public const int TOKEN_NUMBER = 8;
    public const int TOKEN_TRUE = 9;
    public const int TOKEN_FALSE = 10;
    public const int TOKEN_NULL = 11;

    private const int BUILDER_CAPACITY = 2000;

    /// <summary>
    /// Parses the string json into a value
    /// </summary>
    /// <param name="json">A JSON string.</param>
    /// <returns>An ArrayList, a Hashtable, a double, a string, null, true, or false</returns>
    public static object JsonDecode(string json)
    {
        bool success = true;

        return JsonDecode(json, ref success);
    }

    /// <summary>
    /// Parses the string json into a value; and fills 'success' with the successfullness of the parse.
    /// </summary>
    /// <param name="json">A JSON string.</param>
    /// <param name="success">Successful parse?</param>
    /// <returns>An ArrayList, a Hashtable, a double, a string, null, true, or false</returns>
    public static object JsonDecode(string json, ref bool success)
    {
        success = true;
        if (json != null) {
            char[] charArray = json.ToCharArray();
            int index = 0;
            object value = ParseValue(charArray, ref index, ref success);
            return value;
        } else {
            return null;
        }
    }

    /// <summary>
    /// Converts a Hashtable / ArrayList object into a JSON string
    /// </summary>
    /// <param name="json">A Hashtable / ArrayList</param>
    /// <returns>A JSON encoded string, or null if object 'json' is not serializable</returns>
    public static string JsonEncode(object json)
    {
        StringBuilder builder = new StringBuilder(BUILDER_CAPACITY);
        bool success = SerializeValue(json, builder);
        return (success ? builder.ToString() : null);
    }

    protected static Hashtable ParseObject(char[] json, ref int index, ref bool success)
    {
        Hashtable table = new Hashtable();
        int token;

        // {
        NextToken(json, ref index);

        bool done = false;
        while (!done) {
            token = LookAhead(json, index);
            if (token == JSON.TOKEN_NONE) {
                success = false;
                return null;
            } else if (token == JSON.TOKEN_COMMA) {
                NextToken(json, ref index);
            } else if (token == JSON.TOKEN_CURLY_CLOSE) {
                NextToken(json, ref index);
                return table;
            } else {

                // name
                string name = ParseString(json, ref index, ref success);
                if (!success) {
                    success = false;
                    return null;
                }

                // :
                token = NextToken(json, ref index);
                if (token != JSON.TOKEN_COLON) {
                    success = false;
                    return null;
                }

                // value
                object value = ParseValue(json, ref index, ref success);
                if (!success) {
                    success = false;
                    return null;
                }

                table[name] = value;
            }
        }

        return table;
    }

    protected static ArrayList ParseArray(char[] json, ref int index, ref bool success)
    {
        ArrayList array = new ArrayList();

        // [
        NextToken(json, ref index);

        bool done = false;
        while (!done) {
            int token = LookAhead(json, index);
            if (token == JSON.TOKEN_NONE) {
                success = false;
                return null;
            } else if (token == JSON.TOKEN_COMMA) {
                NextToken(json, ref index);
            } else if (token == JSON.TOKEN_SQUARED_CLOSE) {
                NextToken(json, ref index);
                break;
            } else {
                object value = ParseValue(json, ref index, ref success);
                if (!success) {
                    return null;
                }

                array.Add(value);
            }
        }

        return array;
    }

    protected static object ParseValue(char[] json, ref int index, ref bool success)
    {
        switch (LookAhead(json, index)) {
            case JSON.TOKEN_STRING:
                return ParseString(json, ref index, ref success);
            case JSON.TOKEN_NUMBER:
                return ParseNumber(json, ref index, ref success);
            case JSON.TOKEN_CURLY_OPEN:
                return ParseObject(json, ref index, ref success);
            case JSON.TOKEN_SQUARED_OPEN:
                return ParseArray(json, ref index, ref success);
            case JSON.TOKEN_TRUE:
                NextToken(json, ref index);
                return true;
            case JSON.TOKEN_FALSE:
                NextToken(json, ref index);
                return false;
            case JSON.TOKEN_NULL:
                NextToken(json, ref index);
                return null;
            case JSON.TOKEN_NONE:
                break;
        }

        success = false;
        return null;
    }

    protected static string ParseString(char[] json, ref int index, ref bool success)
    {
        StringBuilder s = new StringBuilder(BUILDER_CAPACITY);
        char c;

        EatWhitespace(json, ref index);

        // "
        c = json[index++];

        bool complete = false;
        while (!complete) {

            if (index == json.Length) {
                break;
            }

            c = json[index++];
            if (c == '"') {
                complete = true;
                break;
            } else if (c == '\\') {

                if (index == json.Length) {
                    break;
                }
                c = json[index++];
                if (c == '"') {
                    s.Append('"');
                } else if (c == '\\') {
                    s.Append('\\');
                } else if (c == '/') {
                    s.Append('/');
                } else if (c == 'b') {
                    s.Append('\b');
                } else if (c == 'f') {
                    s.Append('\f');
                } else if (c == 'n') {
                    s.Append('\n');
                } else if (c == 'r') {
                    s.Append('\r');
                } else if (c == 't') {
                    s.Append('\t');
                } else if (c == 'u') {
                    int remainingLength = json.Length - index;
                    if (remainingLength >= 4) {
                        // parse the 32 bit hex into an integer codepoint
                        uint codePoint;
                        if (!(success = UInt32.TryParse(new string(json, index, 4), NumberStyles.HexNumber, CultureInfo.InvariantCulture, out codePoint))) {
                            return "";
                        }
                        // convert the integer codepoint to a unicode char and add to string
                        s.Append(Char.ConvertFromUtf32((int)codePoint));
                        // skip 4 chars
                        index += 4;
                    } else {
                        break;
                    }
                }

            } else {
                s.Append(c);
            }

        }

        if (!complete) {
            success = false;
            return null;
        }

        return s.ToString();
    }

    protected static double ParseNumber(char[] json, ref int index, ref bool success)
    {
        EatWhitespace(json, ref index);

        int lastIndex = GetLastIndexOfNumber(json, index);
        int charLength = (lastIndex - index) + 1;

        double number;
        success = Double.TryParse(new string(json, index, charLength), NumberStyles.Any, CultureInfo.InvariantCulture, out number);

        index = lastIndex + 1;
        return number;
    }

    protected static int GetLastIndexOfNumber(char[] json, int index)
    {
        int lastIndex;

        for (lastIndex = index; lastIndex < json.Length; lastIndex++) {
            if ("0123456789+-.eE".IndexOf(json[lastIndex]) == -1) {
                break;
            }
        }
        return lastIndex - 1;
    }

    protected static void EatWhitespace(char[] json, ref int index)
    {
        for (; index < json.Length; index++) {
            if (" \t\n\r".IndexOf(json[index]) == -1) {
                break;
            }
        }
    }

    protected static int LookAhead(char[] json, int index)
    {
        int saveIndex = index;
        return NextToken(json, ref saveIndex);
    }

    protected static int NextToken(char[] json, ref int index)
    {
        EatWhitespace(json, ref index);

        if (index == json.Length) {
            return JSON.TOKEN_NONE;
        }

        char c = json[index];
        index++;
        switch (c) {
            case '{':
                return JSON.TOKEN_CURLY_OPEN;
            case '}':
                return JSON.TOKEN_CURLY_CLOSE;
            case '[':
                return JSON.TOKEN_SQUARED_OPEN;
            case ']':
                return JSON.TOKEN_SQUARED_CLOSE;
            case ',':
                return JSON.TOKEN_COMMA;
            case '"':
                return JSON.TOKEN_STRING;
            case '0': case '1': case '2': case '3': case '4':
            case '5': case '6': case '7': case '8': case '9':
            case '-':
                return JSON.TOKEN_NUMBER;
            case ':':
                return JSON.TOKEN_COLON;
        }
        index--;

        int remainingLength = json.Length - index;

        // false
        if (remainingLength >= 5) {
            if (json[index] == 'f' &&
                json[index + 1] == 'a' &&
                json[index + 2] == 'l' &&
                json[index + 3] == 's' &&
                json[index + 4] == 'e') {
                index += 5;
                return JSON.TOKEN_FALSE;
            }
        }

        // true
        if (remainingLength >= 4) {
            if (json[index] == 't' &&
                json[index + 1] == 'r' &&
                json[index + 2] == 'u' &&
                json[index + 3] == 'e') {
                index += 4;
                return JSON.TOKEN_TRUE;
            }
        }

        // null
        if (remainingLength >= 4) {
            if (json[index] == 'n' &&
                json[index + 1] == 'u' &&
                json[index + 2] == 'l' &&
                json[index + 3] == 'l') {
                index += 4;
                return JSON.TOKEN_NULL;
            }
        }

        return JSON.TOKEN_NONE;
    }

    protected static bool SerializeValue(object value, StringBuilder builder)
    {
        bool success = true;

        if (value is string) {
            success = SerializeString((string)value, builder);
        } else if (value is Hashtable) {
            success = SerializeObject((Hashtable)value, builder);
        } else if (value is ArrayList) {
            success = SerializeArray((ArrayList)value, builder);
        } else if ((value is Boolean) && ((Boolean)value == true)) {
            builder.Append("true");
        } else if ((value is Boolean) && ((Boolean)value == false)) {
            builder.Append("false");
        } else if (value is ValueType) {
            // thanks to ritchie for pointing out ValueType to me
            success = SerializeNumber(Convert.ToDouble(value), builder);
        } else if (value == null) {
            builder.Append("null");
        } else {
            success = false;
        }
        return success;
    }

    protected static bool SerializeObject(Hashtable anObject, StringBuilder builder)
    {
        builder.Append("{");

        IDictionaryEnumerator e = anObject.GetEnumerator();
        bool first = true;
        while (e.MoveNext()) {
            string key = e.Key.ToString();
            object value = e.Value;

            if (!first) {
                builder.Append(", ");
            }

            SerializeString(key, builder);
            builder.Append(":");
            if (!SerializeValue(value, builder)) {
                return false;
            }

            first = false;
        }

        builder.Append("}");
        return true;
    }

    protected static bool SerializeArray(ArrayList anArray, StringBuilder builder)
    {
        builder.Append("[");

        bool first = true;
        for (int i = 0; i < anArray.Count; i++) {
            object value = anArray[i];

            if (!first) {
                builder.Append(", ");
            }

            if (!SerializeValue(value, builder)) {
                return false;
            }

            first = false;
        }

        builder.Append("]");
        return true;
    }

    protected static bool SerializeString(string aString, StringBuilder builder)
    {
        builder.Append("\"");

        char[] charArray = aString.ToCharArray();
        for (int i = 0; i < charArray.Length; i++) {
            char c = charArray[i];
            if (c == '"') {
                builder.Append("\\\"");
            } else if (c == '\\') {
                builder.Append("\\\\");
            } else if (c == '\b') {
                builder.Append("\\b");
            } else if (c == '\f') {
                builder.Append("\\f");
            } else if (c == '\n') {
                builder.Append("\\n");
            } else if (c == '\r') {
                builder.Append("\\r");
            } else if (c == '\t') {
                builder.Append("\\t");
            } else {
                int codepoint = Convert.ToInt32(c);
                if ((codepoint >= 32) && (codepoint <= 126)) {
                    builder.Append(c);
                } else {
                    builder.Append("\\u" + Convert.ToString(codepoint, 16).PadLeft(4, '0'));
                }
            }
        }

        builder.Append("\"");
        return true;
    }

    protected static bool SerializeNumber(double number, StringBuilder builder)
    {
        builder.Append(Convert.ToString(number, CultureInfo.InvariantCulture));
        return true;
    }
}

//parse and show entire json in key-value pair
    Hashtable HTList = (Hashtable)JSON.JsonDecode("completejsonstring");
        public void GetData(Hashtable HT)
        {           
            IDictionaryEnumerator ienum = HT.GetEnumerator();
            while (ienum.MoveNext())
            {
                if (ienum.Value is ArrayList)
                {
                    ArrayList arnew = (ArrayList)ienum.Value;
                    foreach (object obj in arnew)                    
                    {
                        Hashtable hstemp = (Hashtable)obj;
                        GetData(hstemp);
                    }
                }
                else
                {
                    Console.WriteLine(ienum.Key + "=" + ienum.Value);
                }
            }
        }