Dapper.FluentMap

Provides a simple API to fluently map POCO properties to database columns when using Dapper.

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Windows	Linux/OSX	NuGet

Introduction

This Dapper extension allows you to fluently congfigure the mapping between POCO properties and database columns. This keeps your POCO's clean of mapping attributes. The functionality is similar to Entity Framework Fluent API. If you have any questions, suggestions or bugs, please don't hesitate to contact me or create an issue.

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Download

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Usage

Manual mapping

You can map property names manually using the EntityMap<TEntity> class. When creating a derived class, the constructor gives you access to the Map method, allowing you to specify to which database column name a certain property of TEntity should map to.

public class ProductMap : EntityMap<Product>
{
    public ProductMap()
    {
        // Map property 'Name' to column 'strName'.
        Map(p => p.Name)
            .ToColumn("strName");
            
        // Ignore the 'LastModified' property when mapping.
        Map(p => p.LastModified)
            .Ignore();
    }
}

Column names are mapped case sensitive by default. You can change this by specifying the caseSensitive parameter in the ToColumn() method: Map(p => p.Name).ToColumn("strName", caseSensitive: false).

Initialization:

FluentMapper.Initialize(config =>
    {
       config.AddMap(new ProductMap());
    });

Convention based mapping

When you have a lot of entity types, creating manual mapping classes can become plumbing. If your column names adhere to some kind of naming convention, you might be better off by configuring a mapping convention.

You can create a convention by creating a class which derives from the Convention class. In the contructor you can configure the property conventions:

public class TypePrefixConvention : Convention
{
    public TypePrefixConvention()
    {
        // Map all properties of type int and with the name 'id' to column 'autID'.
        Properties<int>()
            .Where(c => c.Name.ToLower() == "id")
            .Configure(c => c.HasColumnName("autID"));

        // Prefix all properties of type string with 'str' when mapping to column names.
        Properties<string>()
            .Configure(c => c.HasPrefix("str"));

        // Prefix all properties of type int with 'int' when mapping to column names.
        Properties<int>()
            .Configure(c => c.HasPrefix("int"));
    }
}

When initializing Dapper.FluentMap with conventions, the entities on which a convention applies must be configured. You can choose to either configure the entities explicitly or use assembly scanning.

FluentMapper.Initialize(config =>
    {
        // Configure entities explicitly.
        config.AddConvention<TypePrefixConvention>()
              .ForEntity<Product>()
              .ForEntity<Order>;

        // Configure all entities in a certain assembly with an optional namespaces filter.
        config.AddConvention<TypePrefixConvention>()
              .ForEntitiesInAssembly(typeof(Product).Assembly, "App.Domain.Model");

        // Configure all entities in the current assembly with an optional namespaces filter.
        config.AddConvention<TypePrefixConvention>()
              .ForEntitiesInCurrentAssembly("App.Domain.Model.Catalog", "App.Domain.Model.Order");
    });

Transformations

The convention API allows you to configure transformation of property names to database column names. An implementation would look like this:

public class PropertyTransformConvention : Convention
{
    public PropertyTransformConvention()
    {
        Properties()
            .Configure(c => c.Transform(s => Regex.Replace(input: s, pattern: "([A-Z])([A-Z][a-z])|([a-z0-9])([A-Z])", replacement: "$1$3_$2$4")));
    }
}

This configuration will map camel case property names to underscore seperated database column names (UrlOptimizedName -> Url_Optimized_Name).

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Dommel

Dommel contains a set of extensions methods providing easy CRUD operations using Dapper. One of the goals was to provide extension points for resolving table and column names. Dapper.FluentMap.Dommel implements certain interfaces of Dommel and uses the configured mapping. It also provides more mapping functionality.

PM> Install-Package Dapper.FluentMap.Dommel

Usage

DommelEntityMap<TEntity>

This class derives from EntityMap<TEntity> and allows you to map an entity to a database table using the ToTable() method:

public class ProductMap : DommelEntityMap<TEntity>
{
    public ProductMap()
    {
        ToTable("tblProduct");
        
        // ...
    }
}

DommelPropertyMap<TEntity>

This class derives PropertyMap<TEntity> and allows you to specify the key property of an entity using the IsKey method:

public class ProductMap : DommelEntityMap<TEntity>
{
    public ProductMap()
    {
        Map(p => p.Id).IsKey();
    }
}

You can configure Dapper.FluentMap.Dommel in the FluentMapper.Initialize() method:

FluentMapper.Initialize(config =>
    {
        config.AddMap(new ProductMap());
        config.ForDommel();
    });