Members and names

Naming policies

By default, a key is the name of the property, such as DisplayName. Set PropertyNamingPolicy to convert every name:

For another convention, derive a class from YamlNamingPolicy and override ConvertName. DictionaryKeyPolicy converts the keys of dictionaries when writing; by default they are written unchanged.

[YamlNamingPolicy] overrides the policy of the options for all the members of a type, or for one member:

[YamlNamingPolicy(YamlKnownNamingPolicy.SnakeCaseLower)]
internal sealed class Product
{
    public int Id { get; set; }                       // id

    [YamlNamingPolicy(YamlKnownNamingPolicy.CamelCase)]
    public string? DisplayName { get; set; }          // displayName

    public DateTime CreationDate { get; set; }        // creation_date
}

Rename a member

[YamlPropertyName] sets the key of one member. It wins over every naming policy:

public sealed class Product
{
    public int Id { get; set; }

    [YamlPropertyName("name")]
    public string DisplayName { get; set; } = "";

    public string[] Tags { get; set; } = [];
}

Two members that end up with the same key throw an InvalidOperationException the first time the type is used.

Ignore members

DefaultIgnoreCondition sets which members are skipped, and [YamlIgnore] overrides it for a type or a member:

[YamlIgnore(Condition = YamlIgnoreCondition.WhenWritingNull)]
internal sealed class Product
{
    public string? Name { get; set; }                 // omitted when null

    [YamlIgnore(Condition = YamlIgnoreCondition.Never)]
    public string? Description { get; set; }          // always written

    [YamlIgnore]
    public string? Secret { get; set; }               // never serialized nor deserialized
}

[YamlIgnore] without a condition means Always. IgnoreReadOnlyProperties and IgnoreReadOnlyFields skip the members that have no setter when writing.

Fields and non-public members

Only the public properties are serialized by default. Set IncludeFields to also serialize the public fields. Mark a non-public property or field with [YamlInclude] to serialize it.

Order the members

Members are written in declaration order, from the base type to the derived type. [YamlPropertyOrder] changes the position of a member: lower values come first, and a member without the attribute has the order 0.

internal sealed class Product
{
    [YamlPropertyOrder(1)]
    public int Id { get; set; }

    [YamlPropertyOrder(2)]
    public string? Name { get; set; }
}

To sort the keys by name instead, see Key order.

Enum values

An enum value is written with the name of its member. [YamlEnumMemberName] sets another name:

internal enum Level
{
    Low,

    [YamlEnumMemberName("very-high")]
    VeryHigh,                                         // very-high
}

When reading, the name is matched ignoring the case, and a number is accepted as the numeric value of the member.