I'm starting to migrate some code I have from Newtonsoft.Json
to System.Text.Json
in a .net Core 3.0 app.
I migrated the properties from
[JsonProperty("id")]
to [JsonPropertyName("id")]
but I have some properties decorated with the JsonConverter
attribute as:
[JsonConverter(typeof(DateTimeConverter))] [JsonPropertyName("birth_date")] DateTime BirthDate{ get; set; }
But I cannot find the equivalent of this Newtonsoft converter in System.Text.Json
Does someone know how can this be achieved in .net Core 3.0?
Thanks!
Json does case-insensitive property name matching by default. The System. Text. Json default is case-sensitive, which gives better performance since it's doing an exact match.
The JsonConverterAttribute specifies which JsonConverter is used to convert an object. The attribute can be placed on a class or a member. When placed on a class, the JsonConverter specified by the attribute will be the default way of serializing that class.
A common way to deserialize JSON is to first create a class with properties and fields that represent one or more of the JSON properties. Then, to deserialize from a string or a file, call the JsonSerializer. Deserialize method.
System.Text.Json
now supports custom type converters in .NET 3.0 preview-7 and above.
You can add converters that match on type, and use the JsonConverter
attribute to use a specific converter for a property.
Here's an example to convert between long
and string
(because javascript doesn't support 64-bit integers).
public class LongToStringConverter : JsonConverter<long> { public override long Read(ref Utf8JsonReader reader, Type type, JsonSerializerOptions options) { if (reader.TokenType == JsonTokenType.String) { // try to parse number directly from bytes ReadOnlySpan<byte> span = reader.HasValueSequence ? reader.ValueSequence.ToArray() : reader.ValueSpan; if (Utf8Parser.TryParse(span, out long number, out int bytesConsumed) && span.Length == bytesConsumed) return number; // try to parse from a string if the above failed, this covers cases with other escaped/UTF characters if (Int64.TryParse(reader.GetString(), out number)) return number; } // fallback to default handling return reader.GetInt64(); } public override void Write(Utf8JsonWriter writer, long value, JsonSerializerOptions options) { writer.WriteStringValue(value.ToString()); } }
Register the converter by adding it to the Converters
list in JsonSerializerOptions
services.AddControllers().AddJsonOptions(options => { options.JsonSerializerOptions.Converters.Add(new LongToStringConverter()); });
Note: The current release doesn't support nullable types yet.
You can find the JsonConverterAttribute
in the namespace System.Text.Json.Serialization
.
https://docs.microsoft.com/en-us/dotnet/api/system.text.json.serialization.jsonconverterattribute?view=netcore-3.0
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