将字符串反序列化为JSON对象时出错

Question

I have a php file which reads a .txt file and sends it via a php server to ac# unity script. Below is a snippet of the text file showing the first 3 lines:

{ "lemma" : "aljotta", "gloss" : "Fisħ soup" }
{ "lemma" : "arguzin", "gloss" : "Slave driver" }
{ "lemma" : "armunjaka", "gloss" : "Armunjaka" }

This is the php script:

<?php
$file = fopen("lemmas.txt", "r");
echo fread($file, filesize("lemmas.txt"));
fclose($file);
?>

In ac# script, the text is returned and each line is separated into an array (string[] lines) slot as seen below:

IEnumerator GetTextFromFile()
    {
        bool succcessful = true;
        WWWForm form = new WWWForm();
        WWW www = new WWW("http://localhost:9000/tounity.php", form);

        yield return www;

        if(www.error != null)
        {
            succcessful = false;
        }
        else
        {
            succcessful = true;
        }

        if (succcessful)
        {
            populateWordList(www.text);
        }
    }

 void populateWordList(string text)
    {
        string[] textArray = text.Split('\n');
        wordsList = gameDatabase.GetWords(textArray);
    }

The array is then passed to a method which deserializes each line into an object of class GameDatabase as seen in the image below:

public string lemma { get; set; } 
public string gloss { get; set; }

public GameDatabase(string lemma, string gloss)
{
    this.lemma = lemma;
    this.gloss = gloss;
}

public  ArrayList GetWords(string[] lines)
{
    foreach (string line in lines)
    {

        GameDatabase gd = JsonConvert.DeserializeObject<GameDatabase>(line);
        lemmasAndGlossesList.Add(new GameDatabase(gd.lemma, gd.gloss));
    }

    foreach(GameDatabase line in lemmasAndGlossesList)
    {
        Debug.Log(line.lemma + "------" + line.gloss);
    }

    return lemmasAndGlossesList;
}

The error occurs in GameDatabase gd = JsonConvert.DeserializeObject<GameDatabase>(line); and returns

JsonReaderException: Unexpected character encountered while parsing value: . Path '', line 0, position 0.

I have searched extensively, however, haven't found anything that works. Any help would be greatly appreciated. It is worth noting that this problem doesn't happen when loading the text file directly into unity without using php.

---

EDIT

---

When using the vs debugger this is the value in the line to be deserialized:

The JSON visualiser of Visual Studio 2019 however reports this:

Answer 1

Thanks to Jonathon K's comment and your reply we can see the data returned by the PHP script starts with a BOM : the first three bytes. This nice article explains how to handle such data properly. In short: use a StreamReader to read the data.

This little program demonstrates how it could work with your data:

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


public class Program
{
    public static void Main()
    {
        var bytes = new byte[] {
            0xEF,0xBB,0xBF,0x7B,0x20,0x22,0x6C,0x65,0x6D,0x6D,0x61,0x22,
            0x20,0x3A,0x20,0x22,0x61,0x72,0x67,0x75,0x7A,0x69,0x6E,0x22,
            0x2C,0x20,0x22,0x67,0x6C,0x6F,0x73,0x73,0x22,0x20,0x3A,0x20,
            0x22,0x53,0x6C,0x61,0x76,0x65,0x20,0x64,0x72,0x69,0x76,0x65,
            0x72,0x22,0x20,0x7D};

        string json;
        using(var ms = new MemoryStream(bytes))
        using(var sr = new StreamReader(ms))
        {
            json = sr.ReadToEnd();
            Console.WriteLine(json);
        }

        // I'm using dynamic here. In your case you can use GameDatabase
        dynamic obj = JsonConvert.DeserializeObject(json);
        Console.WriteLine(obj.lemma);
    }
}

Output:

{ "lemma" : "arguzin", "gloss" : "Slave driver" }
arguzin

Answer 2

I dont know the c# sintax but this will work.

change your JSON file.

[
    { "lemma" : "aljotta", "gloss" : "Fisħ soup" },
    { "lemma" : "arguzin", "gloss" : "Slave driver" },
    { "lemma" : "armunjaka", "gloss" : "Armunjaka" }
]

apply JsonConvert.DeserializeObject to www.text

for (GameDatabase line in JsonConvert.DeserializeObject<GameDatabase[]>(www.text)){
    Debug.Log(line.lemma + "------" + line.gloss);
}

Maybe my c# syntax is wrong but i would that u understand my idea

Answer 3

I think it's possible that you're going about deserialization wrong by using JsonConvert.

Instead, read up on this documentation and try to use the Unity functions: https://docs.unity3d.com/Manual/JSONSerialization.html

For starters, you're defining lemma and gloss incorrectly if you're looking to use them for deserializing JSON in Unity. See this answer for more info: Serialize and Deserialize Json and Json Array in Unity