JsonSerializerSettings常用配置整理
1.忽略某些屬性
MemberSerialization.OptIn
默認情況下,所有的成員不會被序列化,類中的成員只有標有特性JsonProperty的才會被序列化,當類的成員很多,但客戶端僅僅需要一部分數據時,很有用
1 [JsonObject(MemberSerialization.OptIn)]
2 public class TestClass
3 {
4 public int A { get; set; }
5 public long B { get; set; }
6 public string C { get; set; }
7 [JsonProperty]
8 public DateTime D { get; set; }
9 public TestEnum E { get; set; }
10 [JsonIgnore]
11 public TestClass F { get; set; }
12 public List<TestClass> G { get; set; }
13 public bool H { get; set; }
14 }
15 public enum TestEnum
16 {
17 TestEnum0 = 0,
18 TestEnum1 = 1,
19 TestEnum2 = 2,
20 TestEnum3 = 3,
21 }
22 [JsonObject(MemberSerialization.OptIn)]
23 public class Person
24 {
25 [JsonIgnore]
26 public string Name { get; set; }
27 [JsonProperty]
28 public int Age { get; set; }
29 public DateTime BirthDay { get; set; }
30 }
1 Console.WriteLine(JsonConvert.SerializeObject(new Person { Name = "test", Age = 18, BirthDay = new DateTime(2011, 1, 1) }));
2 TestClass testClass = new TestClass
3 {
4 A = 1,
5 B = 2,
6 C = "C",
7 D = DateTime.Now,
8 E = TestEnum.TestEnum1,
9 F = new TestClass
10 {
11 A = 11,
12 B = 22,
13 C = "Cc",
14 D = DateTime.Now,
15 E = TestEnum.TestEnum2,
16 F = new TestClass()
17 },
18 G = new List<TestClass>
19 {
20 new TestClass
21 {
22 A=111,
23 B=222,
24 C="CCC",
25 E=TestEnum.TestEnum1,
26 F=new TestClass()
27 }
28 }
29 };
30 Console.WriteLine(JsonConvert.SerializeObject(testClass));
輸出結果：
{"Age":18}
{"D":"2019-11-26T10:37:33.7655514+08:00"}
MemberSerialization.OptOut
默認類中所有公有成員會被序列化,如果不想被序列化,可以用特性JsonIgnore
將上面的代碼OptIn改為OptOut輸出結果：
{"Age":18,"BirthDay":"2011-01-01T00:00:00"}
{"A":1,"B":2,"C":"C","D":"2019-11-26T15:49:37.9507028+08:00","E":1,"G":[{"A":111,"B":222,"C":"CCC","D":"0001-01-01T00:00:00","E":1,"G":null,"H":false}],"H":false}
2.默認值的處理
DefaultValueHandling.Ignore 序列化和反序列化時,忽略默認值
1 TestClass testClass = new TestClass
2 {
3 A = 1,
4 B = 2,
5 C = "C",
6 D = DateTime.Now,
7 E = TestEnum.TestEnum1,
8 F = new TestClass
9 {
10 A = 11,
11 B = 22,
12 C = "Cc",
13 D = DateTime.Now,
14 E = TestEnum.TestEnum2,
15 F = new TestClass()
16 },
17 G = new List<TestClass>
18 {
19 new TestClass
20 {
21 A=111,
22 B=222,
23 C="CCC",
24 E=TestEnum.TestEnum1,
25 F=new TestClass()
26 }
27 }
28 };
29 JsonSerializerSettings settings = new JsonSerializerSettings();
30 settings.DefaultValueHandling = DefaultValueHandling.Ignore;
31 Console.WriteLine(JsonConvert.SerializeObject(testClass,settings));
輸出結果：
{"A":1,"B":2,"C":"C","D":"2019-11-26T15:56:21.7204132+08:00","E":1,"G":[{"A":111,"B":222,"C":"CCC","E":1}]}
DefaultValueHandling.Include 序列化和反序列化時,包含默認值
將JsonSerializerSettings.DefaultValueHandling屬性設為DefaultValueHandling.Include輸出結果：
{"A":1,"B":2,"C":"C","D":"2019-11-26T16:21:48.5429746+08:00","E":1,"G":[{"A":111,"B":222,"C":"CCC","D":"0001-01-01T00:00:00","E":1,"G":null,"H":false}],"H":false}
DefaultValueHandling.Populate 在反序列化時，具有默認值但沒有JSON的成員將被設置為其默認值。
DefaultValueHandling.IgnoreAndPopulate 在序列化對象時忽略成員值與成員默認值相同的成員，在反序列化時將成員設置為其默認值
不指定的情況下，序列化時 默認 包含-DefaultValueHandling.Include
3.空值的處理
設置JsonSerializerSettings.NullValueHandling屬性
對序列化過程中所有屬性生效的，想單獨對某一個屬性生效可以使用JsonProperty
值為NullValueHandling.Ignore時，輸出結果為：
{"A":1,"B":2,"C":"C","D":"2019-11-26T16:34:21.3205145+08:00","E":1,"G":[{"A":111,"B":222,"C":"CCC","D":"0001-01-01T00:00:00","E":1,"H":false}],"H":false}
值為NullValueHandling.Include時，輸出結果為：
{"A":1,"B":2,"C":"C","D":"2019-11-26T16:34:21.3205145+08:00","E":1,"G":[{"A":111,"B":222,"C":"CCC","D":"0001-01-01T00:00:00","E":1,"G":null,"H":false}],"H":false}
4.支持非公共成員
序列化時默認都是處理公共成員，如果需要處理非公共成員，就要在該成員上加特性JsonProperty
5.日期處理（DateFormatHandling）
對於Dateime類型日期的格式化，系統自帶的會格式化成iso日期標准{"BirthDay":"2011-01-01T00:00:00"}
解決方案1：添加特性，指定轉換格式
1 public class LongDateTimeConvert: Newtonsoft.Json.Converters.IsoDateTimeConverter
2 {
3 public LongDateTimeConvert() : base()
4 {
5 base.DateTimeFormat = "yyyy-MM-dd";
6 }
7 }
8 //[JsonConverter(typeof(LongDateTimeConvert))]
9 public DateTime BirthDay { get; set; }
輸出結果：{"BirthDay":"2011-01-01"}
解決方案2：指定JsonSerializerSettings.DateFormatString的值
1 JsonSerializerSettings settings = new JsonSerializerSettings();
2 settings.DateFormatString = "yyyy-MM-dd HH:mm:ss";
3 var str = JsonConvert.SerializeObject(new Person { Name = "test", Age = 18, BirthDay = new DateTime(2011, 1, 1) }, settings);
4 Console.WriteLine(str);
輸出結果：{"BirthDay":"2011-01-01 00:00:00"}
同時指定時以特性（即方案1）為准
解決方案3：
object model = new object();
var jsonSettings = new JsonSerializerSettings();
jsonSettings.DateFormatHandling = DatFormatHandling.IsoDateFormat;
jsonSettings.Converters.Add(new Newtonsoft.Json.Converters.IsoDateTimeConverter () {DateTimeFormat = "yyyy-MM-dd HH:mm:ss.fff"});
string content = JsonConvert.SerializeObject (model,Formatting.Indented,jsonSettings);
6.自定義序列化的字段名稱
實體中定義的屬性名可能不是自己想要的名稱，但是又不能更改實體定義，這個時候可以自定義序列化字段名稱
[JsonProperty(PropertyName = "age")]
public int Age { get; set; }
輸出結果：{"age":18}
7.動態決定屬性是否序列化
指定JsonSerializerSettings.ContractResolver的實例，繼承DefaultContractResolver類，重寫方法
1 public class JsonContractResolver : DefaultContractResolver
2 {
3 protected IEnumerable<string> _excludedProperties;
4 public JsonContractResolver(IEnumerable<string> excludedProperties)
5 {
6 this._excludedProperties = excludedProperties;
7 }
8 protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)
9 {
10 return base.CreateProperties(type, memberSerialization).Where(a=>!this._excludedProperties.Contains(a.PropertyName)).ToList();
11 }
12 }
13 JsonSerializerSettings settings = new JsonSerializerSettings();
14 settings.ContractResolver =new JsonContractResolver(new[] { "Sign" });
15 settings.DateFormatHandling = DateFormatHandling.MicrosoftDateFormat;
16 settings.DateFormatString = "yyyy-MM-dd HH:mm:ss";
17 var str = JsonConvert.SerializeObject(new Person { Name = "test", Age = 18, BirthDay = new DateTime(2011, 1, 1) }, settings);
18 Console.WriteLine(str);
過濾屬性名為Sign的字段，輸出結果：{"age":18,"BirthDay":"2011-01-01T00:00:00"}
8.枚舉值的自定義格式化問題
默認枚舉輸出的是枚舉的 值 {"E":1}
在屬性上加上JsonConverter(typeof(StringEnumConverter))表示將枚舉值轉換成對應的字符串,StringEnumConverter是Newtonsoft.Json內置的轉換類型
輸出結果：{"E":"TestEnum1"}
9.自定義類型轉換
需要擴展類JsonConverter類
10.全局序列化設置
1 JsonSerializerSettings settings = new JsonSerializerSettings();
2 settings.ContractResolver =new JsonContractResolver(new[] { "Sign" });
3 settings.DateFormatHandling = DateFormatHandling.MicrosoftDateFormat;
4 settings.DateFormatString = "yyyy-MM-dd HH:mm:ss";
5 JsonConvert.DefaultSettings = () => settings;
指定JsonConvert.DefaultSettings
11.指定序列化時Key的處理方式：駝峰樣式，默認樣式（ContractResolver）
JsonSerializerSettings settings = new JsonSerializerSettings();
settings.ContractResolver = new CamelCasePropertyNamesContractResolver();
var str = JsonConvert.SerializeObject(new Person { Name = "test", Age = 18, BirthDay = new DateTime(2011, 1, 1) },Formatting.Indented);
Formatting.Indented 格式化json字符串數據,鋸齒狀的
輸出結果：
{
"sign": false,
"age": 18,
"birthDay": "2011-01-01T00:00:00"
}
12.序列化循環 引用及處理層數
對於關聯表的 對象或列表都不會序列化出來
//設置循環引用，及引用類型序列化的層數。
//注：目前在 EF core中目前不支持延遲加載，無所謂循環引用了
JsonSerializerSettings settings = new JsonSerializerSettings();
settings.Formatting = Formatting.Indented;
settings.MaxDepth = 10; //設置序列化的最大層數
settings.ReferenceLoopHandling = ReferenceLoopHandling.Serialize;//指定如何處理循環引用，None--不序列化，Error-拋出異常，Serialize--仍要序列化
本文參考文檔：
https://blog.csdn.net/u011127019/article/details/72801033
Newtonsoft.Json 官方文檔：https://www.newtonsoft.com/json/help/html/T_Newtonsoft_Json_JsonSerializerSettings.htm