YamlSerializerOptions Class

When false, encountering an alias throws a YamlException.

When false, encountering a node that declares an anchor throws a YamlException.

The default is YamlSequenceItemStyle.Compact, which emits the first mapping key on the same line as the sequence dash when possible. This option is ignored when YamlSerializerOptions.WriteIndented is disabled, because the flow style has no sequence dash.

The default is YamlSequenceItemStyle.Expanded, which keeps nested sequence items on lines following the parent sequence dash. This option is ignored when YamlSerializerOptions.WriteIndented is disabled, because the flow style has no sequence dash.

Converters are evaluated in order and take precedence over built-in converters.

A block sequence used as a mapping value does not need its own indentation level: YAML allows the sequence dashes to sit at the indentation of the parent mapping. When false, the dashes are written at the indentation of the parent mapping instead of being indented by YamlSerializerOptions.IndentSize columns.

This option only affects sequences written as a mapping value. A sequence nested inside another sequence is always indented past its parent dash, because YAML has no unindented form for it. This option is ignored when YamlSerializerOptions.WriteIndented is disabled, because the flow style has no sequence dash.

A value of 0 uses the default limit of 100000.

The document object model does not preserve aliases as a distinct node type, so each alias is expanded into a copy of the anchored subtree. Nesting anchors so that each level references the previous one several times makes the node count grow exponentially while the document grows linearly, which lets a very small payload exhaust memory. Only nodes produced by alias expansion count towards this limit; documents without aliases are never affected, and YamlSerializerOptions.MaxDepth does not help because the growth is in breadth rather than depth.

The serializer applies the same limit to the nodes a merge key replays when its value is an alias (<<: *defaults), as a merged mapping can itself merge other mappings.

A value of 0 uses the default limit of 64.

The assigned instance becomes read-only: its YamlPolymorphismOptions.DerivedTypeMappings are copied, and changing them afterwards throws NotSupportedException. This keeps options that are already in use, and the copies made from them with a with expression, from changing.

A member-level or type-level YamlObjectCreationHandlingAttribute overrides this setting. The default behavior is YamlObjectCreationHandling.Replace.

This value is used to annotate YamlException messages with a source name (for example, a file path) when reporting parse errors.

Factories are evaluated in order, and the first one accepting a type classifies it. Without a factory, union cases are selected by YAML shape alone and a payload matching several cases fails to deserialize. Register YamlUnionTypeStructuralClassifier to also tell mapping cases apart by their keys.

When this is a source-generated YamlSerializerContext and this options instance differs from the context's own options, generated metadata may be initialized for this options instance. Cache and reuse the resulting YamlTypeInfo for repeated operations with the same runtime converter set.

Extension data members still capture unmatched properties when present.

Enabling this option allows tag-based type name activation and should only be used with trusted YAML input.

When false, built-in converters use a fast span-based path for common YAML 1.2 scalars while still honoring quoted scalars as strings. When true, scalar resolution goes through the selected YamlSerializerOptions.Schema.

When true, collections are written using the block style and nested collections are indented by YamlSerializerOptions.IndentSize columns.

When false, collections are written using the flow style, which keeps the whole document on a single line: {a: {b: 1}, c: [2, 3]}. Block YAML expresses nesting through indentation, so the flow style is what makes unindented output possible. YamlSerializerOptions.IndentSize, YamlSerializerOptions.BlockSequenceMappingStyle, and YamlSerializerOptions.BlockSequenceSequenceStyle only apply to the block style and are ignored.