Dapper.PartialUpdate

Dapper.PartialUpdate adds a Partial<T> wrapper and Dapper extension methods that only send explicitly-set fields during INSERT and UPDATE.

Why

Use this when you need patch-style updates/inserts:

• Sometimes you send a full model.
• Sometimes you need to omit fields so they are not written at all.

Partial<T> tracks whether a value has been set (IsSet), and extensions build SQL using only those set fields.

Install

dotnet add package Dapper.PartialUpdate

Quick Example

using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using Dapper.PartialUpdate;

[Table("Fixture")]
public sealed class Fixture
{
    [Key]
    public int Id { get; set; }

    public Partial<int> FixtureType { get; set; }
    public Partial<string?> Name { get; set; }
}

var fixture = new Fixture { Id = 12 };
fixture.Name = "Updated Name";     // marks IsSet = true
fixture.FixtureType = 3;           // marks IsSet = true

await connection.UpdatePartialsAsync(fixture, tx);

Only Name and FixtureType are included in the SET clause.

Partial

var p = new Partial<string>("abc"); // IsSet = true
p.Unset();                          // IsSet = false
p.Value = "xyz";                    // IsSet = true

You can also assign directly with implicit conversion:

entity.Name = "Alice"; // Partial<string> IsSet=true

Extension Methods

DapperPartialExtensions provides:

• UpdatePartials<T>(...)
• UpdatePartialsAsync<T>(...)
• InsertPartials<T>(...)
• InsertPartialsAsync<T>(...)

Update behavior

• Table name from [Table] or class name.
• Key from [Key], or Id, or {TypeName}Id.
• Column names from [Column] or property name.
• Only Partial<T> properties with IsSet == true are updated.
• If no fields are set, update returns 0 without executing SQL.

Insert behavior

• Only set Partial<T> properties are included.
• If no partial fields are set, executes INSERT ... DEFAULT VALUES.

Build NuGet Package (local)

.\pack.ps1

Override version:

.\pack.ps1 -Version 0.1.1

Packages are written to artifacts\nuget.