DataTableMapper 1.4.0

DataTableMapper

Map a DataTable to a class instance via the MapTo<T>() extension method. The table's columns automatically map to the class' properties by name. Attributes are available for mapping to a column with a different name, for default values, and for converting one value to another before setting the property.

Targets netstandard2.0 (.NET Framework 4.6.1+, .NET Core 2.0+) and net10.0.

Install

dotnet add package DataTableMapper

Usage

The extension method signature is:

public static IEnumerable<T> MapTo<T>(this System.Data.DataTable table) where T : new()

Call it:

IEnumerable<MyClass> x = table.MapTo<MyClass>();

Mapping

MapTo attempts to find a value for each property of the class in the following order:

1. ColumnMappingAttribute — map the property to a column with another name (not case sensitive)
2. Property name — search for a column with the property's name (not case sensitive)
3. DefaultValueAttribute — set a default value when steps 1 and 2 could not produce one

Column mapping

By default MapTo maps a property to the table's column with the same name.

Decorate a property with ColumnMappingAttribute to map it to a column with another name. MapTo still falls back to property-name mapping if no match is found. For example, MapTo will look for a column named Id for the property below:

public class MyClass
{
    [ColumnMapping("Id")]
    public int MyClassId { get; set; }
}

ColumnMappingAttribute can be inherited for custom functionality.

Default values

Decorate a property with DefaultValueAttribute to assign a value when no mapping can be done, or when the mapping yields a DBNull:

class Person
{
    [DefaultValue(99)]
    public int Id { get; set; }

    [DefaultValue("Johnny")]
    public string Name { get; set; }

    [DefaultValue(true)]
    public bool IsGreat { get; set; }
}

Conversion

For columns returning a different type to the property type, BoolValueConversionAttribute (shipped with the library) converts a column returning an integer to a boolean with C-like rules — zero is false, any non-zero value is true:

class MyClass
{
    // Looks for a column named "val"; if the row value is non-zero the property is set to true, else false
    [BoolValueConversion]
    public bool Val { get; set; }
}

Extensibility

For a custom conversion (e.g. decryption), create an attribute implementing the IValueConversion interface.

Also inherit ColumnMappingAttribute to get column mapping with the attribute.

Building

Requires the .NET SDK 10 (see global.json).

dotnet build -c Release
dotnet test  -c Release
dotnet pack  DataTableMapper/DataTableMapper.csproj -c Release -o artifacts

Releasing

1. Bump <VersionPrefix> in Directory.Build.props.
2. Commit, then tag: git tag v1.2.0 && git push --follow-tags.
3. The Release workflow verifies the tag matches the project version, packs, and pushes to NuGet.org via Trusted Publishing (OIDC, no stored API key). It needs a nuget-release GitHub environment and a matching Trusted Publishing policy on nuget.org (see .github/workflows/release.yml).

Licence

MIT