Handlers · 2 min read

ClickHouseDecimalToNullableDecimalPropertyHandler

A property handler that maps the ClickHouse Decimal types into a nullable decimal property, rejecting values that do not fit.

A property handler that maps the ClickHouse Decimal types (Decimal32, Decimal64, Decimal128 and Decimal256) into a Nullable<decimal> property. Values that are outside of the range of a decimal are rejected instead of being silently altered.

The Decimal128 and Decimal256 types can hold values that a decimal cannot. Such values are rejected with an OverflowException instead of being silently altered. Use ClickHouseDecimalToStringPropertyHandler to keep every digit of a wide Decimal.

Overview

Name	Description
Class	`ClickHouseDecimalToNullableDecimalPropertyHandler`
Namespace	`RepoDb.PropertyHandlers.ClickHouse`
Package	RepoDb.ClickHouse
Implements	IPropertyHandler`<object, decimal?>`
Column type	The ClickHouse `Decimal32`, `Decimal64`, `Decimal128` and `Decimal256` types
Property type	`decimal?`

Conversions

Method	Direction	Description
Get	Database to property	Converts the value returned by the driver (a `decimal`, a `ClickHouseDecimal`, or any value convertible to `decimal`) into a `decimal?`. `null` and `DBNull` are returned as `null`.
Set	Property to database	Converts the `decimal` into a `ClickHouseDecimal`, to be written into the `Decimal` column. A `null` value is written as `null`.

Exceptions

Exception	Thrown When
`OverflowException`	The value is outside of the range of a `decimal`.

Usability

Bind the handler to the property that maps to a nullable Decimal column.

Attribute

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

    [Map("discount"), PropertyHandler(typeof(ClickHouseDecimalToNullableDecimalPropertyHandler))]
    public decimal? Discount { get; set; }
}

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

using (var connection = new ClickHouseConnection(connectionString))
{
    connection.Insert(new Invoice { Id = 1, Discount = null });
    var invoice = connection.Query<Invoice>(e => e.Id == 1).First();
    // invoice.Discount is null
}

Fluent Mapping

To configure via FluentMapper:

FluentMapper
    .Entity<Invoice>()
    .PropertyHandler<ClickHouseDecimalToNullableDecimalPropertyHandler>(e => e.Discount);

Property Level Mapping

To configure via PropertyHandlerMapper:

PropertyHandlerMapper.Add<Invoice, ClickHouseDecimalToNullableDecimalPropertyHandler>(e => e.Discount, new ClickHouseDecimalToNullableDecimalPropertyHandler(), true);

Type Level Mapping

To apply the handler to every property of the type decimal?:

PropertyHandlerMapper.Add<decimal?, ClickHouseDecimalToNullableDecimalPropertyHandler>(new ClickHouseDecimalToNullableDecimalPropertyHandler(), true);

A type level mapping is process-wide: it is applied to every decimal? property of every entity and connection, not only to the intended column. Prefer the attribute, fluent or property level mapping unless every decimal? property maps to a Decimal column.