Schema validation

IndexSchema declares the expected field set. Attach to the writer and every AddDocument is validated.

Define

var schema = new IndexSchema { StrictMode = true }
    .Add(new FieldMapping("id",    FieldType.String) { IsStored = true, IsRequired = true })
    .Add(new FieldMapping("title", FieldType.Text)   { IsRequired = true })
    .Add(new FieldMapping("price", FieldType.Numeric));

var config = new IndexWriterConfig { Schema = schema };

Generated schemas

With the source generator:

[LeanDocument]
public partial class Product
{
    [LeanString("id", Required = true)]
    public required string Id { get; init; }
    [LeanText("title", Required = true)]
    public required string Title { get; init; }
    [LeanNumeric("price")]
    public double Price { get; init; }
}

var config = new IndexWriterConfig { Schema = ProductIndex.CreateSchema() };

ProductIndex.CreateSchema() uses the [LeanDocument(StrictSchema = ...)] default. Override with ProductIndex.CreateSchema(strict: false).

Strict vs lax

• StrictMode = false (default): unknown fields accepted silently.
• StrictMode = true: unknown fields throw SchemaValidationException.

Required fields throw regardless of mode. Type mismatches always throw.

Per-field analyser

A FieldMapping can override the writer's default analyser:

new FieldMapping("title", FieldType.Text) { Analyser = new EnglishStemmerAnalyser() }

See also

• IndexSchema
• FieldMapping