Json – Ignore property when null using the new Net Core 3.0 Json

.net-core-3.0asp.net-core-3.0jsonjson.netsystem.text.json

When using JSON.Net in ASP.Net Core 2.2 I was able to ignore a property when its value was null when serializing to JSON:

[JsonProperty(NullValueHandling = NullValueHandling.Ignore)]
public DateTime? Created { get; set; }

But when using the new ASP.Net Core 3.0 built in JSON (System.Text.Json) I can’t find an equivalent attribute to ignore a property if its value is null.

I could only find JsonIgnore.

Am I missing something?

Best Answer

I'm looking at .Net Core 3.1, where this should ignore null values

    services.AddControllers().AddJsonOptions(options =>
    {
        options.JsonSerializerOptions.IgnoreNullValues = true;
    });

Note, the above isn't per property/attribute, although there is an attribute which may be helpful JsonIgnoreAttribute

An alternative, to solve your problem might be a JsonConverterAttribute, information on how to write your own converter is here

Related Solutions

C# – JavaScriptSerializer – JSON serialization of enum as string

I have found that Json.NET provides the exact functionality I'm looking for with a StringEnumConverter attribute:

using Newtonsoft.Json;
using Newtonsoft.Json.Converters;

[JsonConverter(typeof(StringEnumConverter))]
public Gender Gender { get; set; }

More details at available on StringEnumConverter documentation.

There are other places to configure this converter more globally:

enum itself if you want enum always be serialized/deserialized as string:

[JsonConverter(typeof(StringEnumConverter))]  
enum Gender { Male, Female }

In case anyone wants to avoid attribute decoration, you can add the converter to your JsonSerializer (suggested by Bjørn Egil):
```
serializer.Converters.Add(new Newtonsoft.Json.Converters.StringEnumConverter()); 
```
and it will work for every enum it sees during that serialization (suggested by Travis).

or JsonConverter (suggested by banana):

JsonConvert.SerializeObject(MyObject, 
    new Newtonsoft.Json.Converters.StringEnumConverter());

Additionally you can control casing and whether numbers are still accepted by using StringEnumConverter(NamingStrategy, Boolean) constructor.

C# – How to ignore a property in class if null, using json.net

An alternate solution using the JsonProperty attribute:

[JsonProperty(NullValueHandling=NullValueHandling.Ignore)]
// or
[JsonProperty("property_name", NullValueHandling=NullValueHandling.Ignore)]

// or for all properties in a class
[JsonObject(ItemNullValueHandling = NullValueHandling.Ignore)]

As seen in this online doc.

Best Answer

Related Solutions

C# – JavaScriptSerializer – JSON serialization of enum as string

C# – How to ignore a property in class if null, using json.net

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