使用JSON.NET和C＃阅读文件和反序列化JSON失败 [英] Using JSON.NET and C# reading file and deserialize the JSON fails

问题描述

我有一个名为movies.json一个JSON文件，其中包含的对象和3电影的数组。在movies.json的JSON看起来是这样的：

I have a JSON file named 'movies.json' which contains an object and an array of 3 movies. The JSON in movies.json looks like this:

{
  "theMovies": [
    {
      "name": "Starship Troopers",
      "year": 1997
    },
    {
      "name": "Ace Ventura: When Nature Calls",
      "year": 1995
    },
    {
      "name": "Big",
      "year": 1988
    }
  ]
}

我也有一个名为Movie类

I also have a class named Movie

public class Movie
{
    public string Name { get; set; }
    public int Year { get; set; }
}

我想将文件读入一个字符串和反序列化的JSON来\\：;电影>（File.ReadAllText（@C

I am trying to read the file into a string and deserialize the JSON to a type of Movie like this:

 Movie movie1 = JsonConvert.DeserializeObject<Movie>(File.ReadAllText(@"c:\Temp\movies.json"));

和这样的：

using (StreamReader file = File.OpenText(@"c:\Temp\movies.json"))
        {
            JsonSerializer serializer = new JsonSerializer();
            Movie movie2 = (Movie)serializer.Deserialize(file, typeof(Movie));
            Console.WriteLine(movie2.Name);
            Console.WriteLine(movie2.Year);
        }

无论是一期工程。无论MOVIE1和MOVIE2显示没有真正的数据观察窗口：

Neither one works. Both movie1 and movie2 show no real data the Watch window:

movie1.Name = null
movie1.Year = 0
movie2.Name = null
movie2.Year = 0

显然有一个里面的数组是行不通的对象。有什么建议么？

Apparently having an object with an array inside is not working. Any suggestions?

推荐答案

在JSON，什么都放在 [] 表示一个集合，任何包含在 {} 表示对象（请参阅我的答案这里 ）。所以，你可以看到你有一个包含名为 theMovies 集合，每2个属性包含3个对象（在这种情况下，电影）的对象。如果你觉得这些在C＃来说，你可以有一个类（将作为根对象，姑且称之为 MyJsonDocument ）包含名单，LT ;电影> 集合（这将作为 theMovies 集合）来保存每个电影实例在

In JSON, anything enclosed in [ ] denotes a collection and anything enclosed in { } denotes an object (see my answer here). So, you can see that you have an object containing a collection called theMovies, consisting of 3 objects (in this case, movies) with 2 properties each. If you think of these in C# terms, you could have a class (which would act as the root object, let's call it MyJsonDocument) containing a List<Movie> collection (which would act as theMovies collection) to hold each Movie instance in.

public class MyJsonDocument
{
    //  JsonProperty indicates how each variable appears in the JSON, _
    //  so the deserializer knows that "theMovies" should be mapped to "Movies". _
    //  Alternatively, your C# vars should have the same name as the JSON vars.
    [JsonProperty("theMovies")]
    public List<Movie> Movies { get; set; }
}

public class Movie
{
    [JsonProperty("name")]
    public string Name { get; set; }
    [JsonProperty("year")]
    public int Year { get; set; }
}

现在，你有你的结构设置：

Now that you have your structure set up:

var myJsonDocument = JsonConvert.DeserializeObject<MyJsonDocument>(File.ReadAllText(@"C:\Users\trashr0x\Desktop\movies.json"));
foreach(Movie movie in myJsonDocument.Movies)
{
    Console.WriteLine(string.Format("{0} ({1})", movie.Name, movie.Year));
}

输出：

Output:

星河战队（1997）

艾丝：当自然召唤（1995）

Ace Ventura: When Nature Calls (1995)

大（1988）

顺便说一句，你还可能要考虑当一些JSON属性是空的会发生什么（例如，没有上市一年为一个特定的电影）。你将不得不转换年度是一个 INT？（空整型），而不是一个 INT 。如果你有信心100％，在JSON属性将总是被填充，那么你可以忽略这一点。

As an aside, you might also want to consider what happens when some of the JSON properties are empty (for example, no year listed for a particular movie). You would have to convert Year to be an int? (nullable integer) instead of an int. If you are 100% confident that all properties in the JSON will be always populated then you can ignore this.

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