Handlers · 2 min read

ByteArrayToFloatArrayPropertyHandler

A property handler that maps a binary-encoded vector column, such as the MySQL VECTOR type, into a float array property.

A property handler that maps a binary-encoded vector column (for example, the MySQL VECTOR type, which is transferred as little-endian IEEE 754 single-precision values) into a float array property.

Overview

Name	Description
Class	`ByteArrayToFloatArrayPropertyHandler`
Namespace	`RepoDb.PropertyHandlers`
Package	RepoDb
Implements	IPropertyHandler`<byte[], float[]>`
Column type	A binary-encoded vector column (for example, the MySQL `VECTOR` type)
Property type	`float[]`

Conversions

Method	Direction	Description
Get	Database to property	Converts the binary vector value into a `float[]`, reading 4 bytes per element as little-endian IEEE 754 single-precision values. A `null` value is returned as `null`.
Set	Property to database	Converts the `float[]` into the binary vector value, writing 4 bytes per element in little-endian order. A `null` array is written as `null`.

Exceptions

Exception	Thrown When
`ArgumentException`	The length of the value returned by the database is not a multiple of 4 bytes.

Usability

Bind the handler to the property that maps to a VECTOR column.

Attribute

public class Embedding
{
    public int Id { get; set; }

    [Map("vector"), PropertyHandler(typeof(ByteArrayToFloatArrayPropertyHandler))]
    public float[] Vector { get; set; }
}

Once bound, the library invokes the handler automatically when the property is read or written.

using (var connection = new MySqlConnection(connectionString))
{
    connection.Insert(new Embedding { Id = 1, Vector = new float[] { 0.1f, 0.2f, 0.3f } });
    var embedding = connection.Query<Embedding>(e => e.Id == 1).First();
    // embedding.Vector is a float[] with 3 elements
}

Fluent Mapping

To configure via FluentMapper:

FluentMapper
    .Entity<Embedding>()
    .PropertyHandler<ByteArrayToFloatArrayPropertyHandler>(e => e.Vector);

Property Level Mapping

To configure via PropertyHandlerMapper:

PropertyHandlerMapper.Add<Embedding, ByteArrayToFloatArrayPropertyHandler>(e => e.Vector, new ByteArrayToFloatArrayPropertyHandler(), true);

Type Level Mapping

To apply the handler to every property of the type float[]:

PropertyHandlerMapper.Add<float[], ByteArrayToFloatArrayPropertyHandler>(new ByteArrayToFloatArrayPropertyHandler(), true);

A type level mapping is process-wide: it is applied to every float[] property of every entity and connection, not only to the intended column. Prefer the attribute, fluent or property level mapping unless every float[] property maps to a binary-encoded vector column.