CSharpEssentials.Json 6.2.0

CSharpEssentials.Json

Enhanced JSON serialization utilities on top of System.Text.Json.

Features

• Enum Conventions: [StringEnum] enums read and write their wire names (AddEnumConventions); other enums keep the host's behavior.
• Multi-Format DateTime: Deserialize from many date formats automatically.
• Polymorphic Serialization: Serialize abstract types and interfaces with a $type discriminator.
• Pre-Configured Options: CamelCase, ignore cycles, ignore nulls, relaxed escaping.

Installation

dotnet add package CSharpEssentials.Json

Usage

Pre-Configured Options

using CSharpEssentials.Json;
using System.Text.Json;

var options = EnhancedJsonSerializerOptions.DefaultOptions;
string json = JsonSerializer.Serialize(myObject, options);

Quick Extensions

ConvertToJson, ConvertFromJson and ConvertToJsonDocument use EnhancedJsonSerializerOptions.DefaultOptions (or the options you pass) through reflection-based serialization. They are annotated [RequiresUnreferencedCode] and [RequiresDynamicCode]; in trimmed or NativeAOT apps call JsonSerializer with a JsonSerializerContext instead.

using System.Text.Json;
using CSharpEssentials.Json;

var user = new { Name = "Alice", Age = 30 };

string json = user.ConvertToJson();
var parsed = json.ConvertFromJson<User>();
JsonDocument doc = json.ConvertToJsonDocument();

JsonElement to CLR Values

Dictionary<string, object> and object deserialize to JsonElement. ToClrObject turns them into plain values: objects become Dictionary<string, object?>, arrays List<object?>, numbers int, long, decimal or double (first that fits).

using System.Text.Json;
using CSharpEssentials.Json;

using JsonDocument doc = JsonDocument.Parse("""{"id":1,"price":9.99,"tags":["a"]}""");

var data = (Dictionary<string, object?>)doc.RootElement.ToClrObject()!;
// data["id"] is int, data["price"] is decimal, data["tags"] is List<object?>

Enum Conventions

AddEnumConventions adds the enum converter for every enum with generated metadata ([StringEnum], see CSharpEssentials.Enums). Other enums are left to the converters already on the options, so a plain enum stays a number unless you add JsonStringEnumConverter yourself.

using System.Text.Json;
using CSharpEssentials.Enums;
using CSharpEssentials.Json;

[StringEnum]
public enum Status { Active, Inactive, [EnumFallback] Unknown }

public enum Level { Low, High }

public sealed record Account(Status Status, Level Level);

// Data mode (the default): tolerant, for values you stored or received from a trusted service
JsonSerializerOptions data = new JsonSerializerOptions(JsonSerializerDefaults.Web)
    .AddEnumConventions(EnumConventions.Default);

// Input mode: strict, for request bodies (AddEnumConventions() in CSharpEssentials.AspNetCore does this for you)
JsonSerializerOptions input = new JsonSerializerOptions(JsonSerializerDefaults.Web)
    .AddEnumConventions(EnumConventions.Default, EnumReadMode.Input);

JsonSerializer.Serialize(new Account(Status.Active, Level.High), data); // {"status":"active","level":1}
JsonSerializer.Deserialize<Account>("""{"status":"gone","level":0}""", data);  // Status.Unknown (fallback)
JsonSerializer.Deserialize<Account>("""{"status":"gone","level":0}""", input); // throws EnumValueJsonException

• Reads accept the wire name, the member name in any casing, aliases and the number of a defined member. Input mode applies EnumConventions.AcceptNumbers, AcceptMemberNames and CaseInsensitive.
• Undefined values ("gone", 999) are rejected with EnumValueJsonException (a JsonException). In Data mode only, they map to the [EnumFallback] member when the enum declares one (EnumConventions.UnknownValue = UnknownEnumValueHandling.UseFallback, the default).
• Writes are the wire name, or the number with writeAs: EnumWireFormat.Number. [Flags] values are JSON arrays.
• EnhancedJsonSerializerOptions.DefaultOptions already calls AddEnumConventions(EnumConventions.Default) (Data mode).
• A [StringEnum] enum without generated metadata (CSE0015) throws when its converter is created instead of falling back to numbers. AddEnumConventionsWithReflection also converts enums without metadata through reflection; it is not trim or AOT safe.

ConditionalStringEnumConverter (4.x) is obsolete and forwards to the same converter in Input mode. It no longer has AllowUndefinedValues: undefined numbers are always rejected. See Migrating from 4.x to 5.0.

StringEnumNaming

StringEnumNaming is obsolete in 5.0 and stays as a working facade over EnumMetadata. In new code use EnumMetadata, EnumValueFormatter, EnumValueParser or the generated ToWireName() and TryParseWire helpers: they are the naming source that JSON, EF Core storage, Swagger schemas and query/route binding all use, so a member is spelled the same everywhere. Names are [JsonStringEnumMemberName] when present, otherwise snake_case_lower.

using CSharpEssentials.Json;

[StringEnum]
public enum Http { OK, HTTPStatus }

StringEnumNaming.GetName(Http.HTTPStatus);                    // "http_status"
StringEnumNaming.GetNames<Http>();                            // ["ok", "http_status"]
StringEnumNaming.TryParse<Http>("HTTPStatus", out var value); // true (policy name, member name or number)

Polymorphic Serialization

public abstract class Animal { public string Name { get; set; } = string.Empty; }
public class Dog : Animal { public string Breed { get; set; } = string.Empty; }

Animal dog = new Dog { Name = "Rex", Breed = "Labrador" };
string json = dog.ConvertToJson(); // {"$type":"Dog", "name":"Rex", "breed":"Labrador"}

Animal? restored = json.ConvertFromJson<Animal>();

Multi-Format DateTime

// All formats work automatically
string[] dates = ["2024-03-14T15:30:45Z", "14.03.2024", "March 14, 2024"];
foreach (var d in dates)
{
    DateTime dt = d.ConvertFromJson<DateTime>();
}