DSeries.DMapper.Core 2.1.2

DMapper

DMapper is a lightweight and efficient .NET object‑mapping library designed to simplify object transformation, deep copying, and recursive property binding using advanced reflection techniques. The latest version (DMapper v6) uses a flattened‑object approach that leverages a flattening engine with Next/Previous pointers for each flattened property. This enables precise control over both relative and absolute property mappings via custom attributes.

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✨ What’s new (2.1.2)

Area	Highlights
Date/Time support	Automatic DateTimeOffset ↔ DateTime bridging. When the source provides a DateTimeOffset and the destination expects a DateTime (or vice versa), DMapper converts for you – even inside collections.
Fine‑grained control	[DMapperConverter] attribute. Attach a bespoke converter class to any destination property for one‑off or domain‑specific transformations (e.g. Unix‑epoch → DateTime). Converters are instantiated once and cached.
Tests	New xUnit suites cover the built‑in bridge, custom converters, and collection scenarios.

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Features

• Flattening Engine with Next/Previous Pointers – Objects are flattened into a dictionary of properties, where each flattened property includes Next and Previous pointers. These pointers can be used as a fallback when an exact key isn’t found during mapping.
• Advanced Recursive Mapping (v6) – The v6 engine maps source objects to destination objects solely by merging their flattened representations. It supports both [BindTo] and [ComplexBind] attributes, enabling you to specify relative or absolute property paths (e.g. x.y.u).
• Automatic Date/Time Bridging (new) – DateTimeOffset → DateTime and DateTime → DateTimeOffset conversions are performed transparently, preserving UTC semantics. Works for single values and elements inside arrays/lists.
• Per‑Property Custom Converters (new) ‑ Decorate a destination member with [DMapperConverter(typeof(MyConverter))]. ‑ Implement IDMapperPropertyConverter and return the transformed value. ‑ Combine with [BindTo] or Fluent‑API mappings.
• Attribute‑Based Mapping ‑ [BindTo] – map from one or more source keys; supports relative and absolute notation. ‑ [ComplexBind] – map nested destination paths from explicit source keys.
• Array & Collection Support – Intermediate collections are created as List<T> and converted into arrays during re‑hydration, ensuring array‑typed properties are properly instantiated.
• Deep Copying and Fluent Extensions – DMapper provides methods for deep copying objects and a Fluent API for programmatic configuration.
• Preserving Unmapped Properties – Non‑null destination values remain untouched unless explicitly remapped.

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Installation

# Package coming soon – for now just pull the source files.

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Using the new Date/Time bridge

public class Source
{
    public DateTimeOffset CreatedAt { get; set; }
}

public class Destination
{
    // No converter needed – handled automatically
    public DateTime CreatedAt { get; set; }
}

var dto  = new Source { CreatedAt = DateTimeOffset.UtcNow };
var view = dto.MapTo<Destination>();            // CreatedAt is UTC DateTime

The direction also works in reverse (DateTime ➜ DateTimeOffset).

Note The bridge uses UTC when a DateTime lacks offset information.

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Writing a custom converter

using DMapper.Attributes;
using DMapper.Converters;

// 1)  Implement the interface
public class UnixEpochConverter : IDMapperPropertyConverter
{
    public object Convert(object src)
    {
        long seconds = Convert.ToInt64(src);
        return DateTimeOffset.FromUnixTimeSeconds(seconds).UtcDateTime;
    }
}

// 2)  Use it on a destination member
public class LogDto
{
    public long Ts;   // Unix‑epoch seconds
}

public class LogModel
{
    [BindTo("Ts")]
    [DMapperConverter(typeof(UnixEpochConverter))]
    public DateTime Timestamp { get; set; }
}

// 3)  Map
var dto   = new LogDto { Ts = 1_718_064_000 };
var model = dto.MapTo<LogModel>();

Custom converters receive the raw source value chosen by [BindTo]/Fluent mapping and must return a value assignable to the destination property.

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Fluent API additions

All new capabilities (Date/Time bridge & value converters) work transparently with the Fluent‑API builder. Simply call builder.Map(...) as before; DMapper will detect converters on the destination member at runtime.

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Installation

Simply add the DMapper source files to your .NET project. No external dependencies are required.

Usage

1. Mapping with DMapper (latest version)

The DMapper (latest version) mapping engine relies solely on the flattened representation of source and destination objects. It performs the following steps:

1. Flatten the Source: The source object is converted into a dictionary of flattened properties with actual values.
2. Flatten the Destination Structure: The destination type’s structure is flattened (values are initially null). Then the actual destination instance is flattened and its non-null values are preserved.
3. Merge: The engine merges direct key matches, processes [BindTo] attributes (adding parent paths to relative candidate keys), and applies [ComplexBind] attributes using absolute keys.
4. Rehydrate: A new destination instance is created by rehydrating the merged flatten dictionary, with all intermediate objects and collections instantiated.

Test Cases

Test 1: Basic Mapping with [BindTo] on Top-Level Properties

public class Source1
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Source { get; set; }
    public Source2 Source2 { get; set; } = new Source2();
}
public class Source2
{
    public string SourceName2 { get; set; } = "SourceName2";
}
public class Destination1
{
    public int Id { get; set; }
    public string Name { get; set; }
    [BindTo("Source")]
    public string Destination { get; set; }
    public Destination2 Source2 { get; set; }
    public string DontChange { get; set; } = "DontChange";
}
public class Destination2
{
    [BindTo("SourceName2")]
    public string DestinationName3 { get; set; }
}

Test 2: Inner Mapping with [BindTo] on Nested Property

public class SourceTest2
{
    public string Outer { get; set; } = "OuterValue";
    public InnerSource Inner { get; set; } = new InnerSource();
}
public class InnerSource
{
    public string InnerProp { get; set; } = "InnerValue";
}
public class DestinationTest2
{
    public string Outer { get; set; }
    public InnerDest Inner { get; set; }
}
public class InnerDest
{
    [BindTo("InnerProp")]
    public string MyInner { get; set; }
}

Test 3: ComplexBind Mapping Using an Absolute Destination Key

public class SourceTest3
{
    public string Data { get; set; } = "DataFromSource";
    public NestedSource Nested { get; set; } = new NestedSource();
}
public class NestedSource
{
    public string Info { get; set; } = "NestedInfo";
}
public class DestinationTest3
{
    public string Data { get; set; }
    [ComplexBind("NestedDestination.Info", "Nested.Info")]
    public NestedDest NestedDestination { get; set; }
}
public class NestedDest
{
    public string Info { get; set; }
}

Test 4: ComplexBind on Inner Property with an Absolute Key

public class SourceTest4
{
    public string Extra { get; set; } = "ExtraValue";
}
public class DestinationTest4
{
    [ComplexBind("Sub.Info", "Extra")]
    public SubDest Sub { get; set; }
}
public class SubDest
{
    public string Info { get; set; }
}

Test 5: Array Mapping with [BindTo]

public class SourceTest5
{
    public string[] Items { get; set; } = new string[] { "Item1", "Item2", "Item3" };
}
public class DestinationTest5
{
    [BindTo("Items")]
    public string[] Items { get; set; }
}

Test 6: Fallback Mapping Using [BindTo] Candidate

public class SourceTest6
{
    public string X { get; set; } = "FallbackValue";
    public string B { get; set; } = "Beta";
}
public class DestinationTest6
{
    [BindTo("X")]
    public string B { get; set; }
}

Test 7: Relative BindTo with Nested Path "B.C"

public class SourceTest7
{
    public NestedSource7 A { get; set; } = new NestedSource7();
}
public class NestedSource7
{
    public NestedSource7Inner B { get; set; } = new NestedSource7Inner();
}
public class NestedSource7Inner
{
    public string C { get; set; } = "Value7";
}
public class DestinationTest7
{
    public DestinationTest7A A { get; set; } = new DestinationTest7A();
}
public class DestinationTest7A
{
    [BindTo("A.B.C")]
    public string X { get; set; }
}

Test 8: Absolute BindTo with Full Path

public class SourceTest8
{
    public string M { get; set; } = "MValue";
    public NestedSource8 N { get; set; } = new NestedSource8();
}
public class NestedSource8
{
    public string O { get; set; } = "OValue";
}
public class DestinationTest8
{
    [BindTo("N.O")]
    public string X { get; set; }
}

Test 9: Nested Relative BindTo on Inner Property

public class SourceTest9
{
    public NestedSource9 A { get; set; } = new NestedSource9();
}
public class NestedSource9
{
    public string Y { get; set; } = "Value9";
}
public class DestinationTest9
{
    public DestinationTest9A A { get; set; } = new DestinationTest9A();
}
public class DestinationTest9A
{
    [BindTo("Y")]
    public string Z { get; set; }
}

Test 10: Mapping a Collection Property (List of Complex Objects)

public class Src1
{
    public string Name { get; set; } = "Pesho";
    public List<Src2> Src2List { get; set; } = new List<Src2> { new Src2(), new Src2() };
}
public class Src2
{
    public int Age { get; set; } = 10;
    public string Name { get; set; } = "John";
}
public class Dest1
{
    public string? Name { get; set; }
    public List<Dest2> Src2List { get; set; }
}
public class Dest2
{
    public int? Age { get; set; }
    public string? Name { get; set; }
}

Test 11: Mapping a Collection (List & Array) of Complex Objects

public class CollectionSource1
{
    public List<CollectionItemSource> Items { get; set; } = new List<CollectionItemSource>
    {
        new CollectionItemSource { Value = "A", Number = 1 },
        new CollectionItemSource { Value = "B", Number = 2 }
    };

    public CollectionItemSource[] ArrayItems { get; set; } = new CollectionItemSource[]
    {
        new CollectionItemSource { Value = "C", Number = 3 },
        new CollectionItemSource { Value = "D", Number = 4 }
    };
}
public class CollectionItemSource
{
    public string Value { get; set; }
    public int Number { get; set; }
}
public class CollectionDestination1
{
    [BindTo("Items")]
    public List<CollectionItemDest> Items { get; set; }

    [BindTo("ArrayItems")]
    public CollectionItemDest[] ArrayItems { get; set; }
}
public class CollectionItemDest
{
    public string Value { get; set; }
    public int Number { get; set; }
}

Test 12: Mapping Nested Collections (List of Lists)

public class NestedCollectionSource
{
    public List<List<CollectionItemSource>> NestedItems { get; set; } = new List<List<CollectionItemSource>>
    {
        new List<CollectionItemSource>
        {
            new CollectionItemSource { Value = "E", Number = 5 },
            new CollectionItemSource { Value = "F", Number = 6 }
        },
        new List<CollectionItemSource>
        {
            new CollectionItemSource { Value = "G", Number = 7 }
        }
    };
}
public class NestedCollectionDestination
{
    public List<List<CollectionItemDest>> NestedItems { get; set; }
}

Test 13: Mapping a List with [BindTo]

public class Src1_13
{
    public string Name { get; set; } = "Pesho";
    public List<Src2_13> Src2List { get; set; } = new List<Src2_13> { new Src2_13(), new Src2_13() };
}
public class Src2_13
{
    public int Age { get; set; } = 10;
    public string Name { get; set; } = "John";
}
public class Dest1_13
{
    public string? Name { get; set; }

    [BindTo("Src2List")]
    public List<Dest2_13> Src2List_13 { get; set; }
}
public class Dest2_13
{
    public int? Age { get; set; }
    public string? Name { get; set; }
}

Test 14: Mapping a List with [BindTo] on Their Properties as Well

public class Src1_14
{
    public string Name { get; set; } = "Pesho";
    public List<Src2_14> Src2List { get; set; } = new List<Src2_14> { new Src2_14(), new Src2_14() };
}
public class Src2_14
{
    public int Age { get; set; } = 10;
    public string Name { get; set; } = "John";
}
public class Dest1_14
{
    public string? Name { get; set; }

    [BindTo("Src2List")]
    public List<Dest2_14> Src2List_13 { get; set; }
}
public class Dest2_14
{
    [BindTo("Age")]
    public int? Age2 { get; set; }
    public string? Name { get; set; }
}

Test 15: Cycle Dependency Mapping (Stack Overflow Test)

Description

Tests the handling of cyclic dependencies in object mapping to prevent infinite recursion.

Source Code

public class SourceTest15
{
    public string Name { get; set; } = "Parent";
    public SourceTest15 Child { get; set; }
}

public class DestinationTest15
{
    public string Name { get; set; }
    public DestinationTest15 Child { get; set; }
}

Expected Behavior

• The mapping should detect circular references and prevent infinite recursion.
• The parent-child structure should be mapped correctly without causing a stack overflow.

Test 16: Multi-Source with Same Destination

Description

Maps multiple source properties to a single destination property.

Source Code

public class SourceTest1_16
{
    public string Name1 { get; set; } = "Source1";
}

public class SourceTest2_16
{
    public string Name2 { get; set; } = "Source2";
}

public class DestinationTest16
{
    [BindTo("Name1, Name2")]
    public string Name { get; set; }
}

Expected Behavior

• The destination Name should be assigned the value of Name1 or Name2 based on availability.

Test 17: Multi ComplexBinding Source with Same Destination

Description

Tests complex binding where multiple sources contribute to the same nested destination object.

Source Code

public class SourceTest1_17
{
    public string Name1 { get; set; } = "Source1";
}

public class SourceTest2_17
{
    public string Name2 { get; set; } = "Source2";
}

public class DestinationTest1_17
{
    [ComplexBind("DestinationTest2_17.Name", "Name2")]
    [ComplexBind("DestinationTest2_17.Name", "Name1")]
    public DestinationTest2_17 DestinationTest2_17 { get; set; }
}

public class DestinationTest2_17
{
    public string Name { get; set; }
}

Expected Behavior

• The DestinationTest2_17.Name should take the first available value from Name1 or Name2.

Test 18: Binding to a Complex Object

Description

Maps a nested complex source object to a corresponding destination object using [BindTo].

Source Code

public class SourceTest1_18
{
    public SourceTest2_18 SourceTest2_18 { get; set; } = new();
}

public class SourceTest2_18
{
    public string Name { get; set; } = "Source";
}

public class DestinationTest1_18
{
    public DestinationTest2_18 DestinationTest2_18 { get; set; }
}

public class DestinationTest2_18
{
    [BindTo("SourceTest2_18.Name")]
    public string Name { get; set; }
}

Expected Behavior

• The DestinationTest2_18.Name should correctly map the value from SourceTest2_18.Name.

Test 19: Binding to a Complex Object with a [BindTo] Attribute on a Complex Object

Description

Maps a complex source object while also binding individual properties inside it.

Source Code

public class SourceTest1_19
{
    public SourceTest2_19 SourceTest2_19 { get; set; } = new();
}

public class SourceTest2_19
{
    public string Name { get; set; } = "Source";
    public int Age { get; set; } = 25;
}

public class DestinationTest1_19
{
    [BindTo("SourceTest2_19")]
    public DestinationTest2_19 DestinationTest2_19 { get; set; }
}

public class DestinationTest2_19
{
    [BindTo("Name")]
    public string Name2 { get; set; }
    public int Age { get; set; }
}

Expected Behavior

• DestinationTest2_19.Name2 should receive the value from SourceTest2_19.Name.
• DestinationTest2_19.Age should be mapped from SourceTest2_19.Age.

Object Flattening with DMapper

Overview

The ObjectFlattener utility in DMapper provides a way to flatten complex objects into key-value pairs, making it easier to work with deeply nested structures. This is especially useful for serialization, mapping, and transformation scenarios.

The utility supports flattening:

• Object Instances: Converts an object into a dictionary with key paths.
• Type Structures: Analyzes a type and produces a structure representation.
• Collections & Arrays: Handles lists, dictionaries, and arrays gracefully.

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Installation

Ensure that your project references the DMapper.Helpers namespace:

using DMapper.Helpers;
using DMapper.Helpers.Models;

If you are using the extension methods:

using DMapper.Extensions;

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Basic Usage

1. Flattening an Object Instance

To flatten an instance of an object:

var myObject = new
{
    Name = "John Doe",
    Address = new { City = "New York", Zip = "10001" },
    Tags = new[] { "Developer", "Blogger" }
};

FlattenResult result = myObject.Flatten();

This will produce key-value pairs like:

Name -> "John Doe"
Address.City -> "New York"
Address.Zip -> "10001"
Tags[0] -> "Developer"
Tags[1] -> "Blogger"

2. Flattening a Type Structure

To get the structure of a type without an instance:

FlattenResult result = typeof(MyClass).Flatten();

This generates a similar dictionary but with null values, representing the type structure.

3. Flattening a Generic Type

FlattenResult result = Flatten<MyClass>();

This is equivalent to calling Flatten(typeof(MyClass)).

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Understanding FlattenResult

A FlattenResult contains:

• FlattenedType: The type of the object that was flattened.
• Properties: A dictionary mapping flattened property paths to FlattenedProperty objects.

Each FlattenedProperty consists of:

• Value: The actual value of the property.
• PropertyType: The type of the property.
• Next and Previous: Pointers to adjacent properties in sorted order, allowing for sequential access.

Example:

foreach (var entry in result.Properties)
{
    Console.WriteLine($"{entry.Key} -> {entry.Value.Value} (Type: {entry.Value.PropertyType.Name})");
}

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Handling Collections

The ObjectFlattener handles lists and arrays using indexed paths:

var obj = new { Numbers = new[] { 1, 2, 3 } };
FlattenResult result = obj.Flatten();

Output:

Numbers[0] -> 1
Numbers[1] -> 2
Numbers[2] -> 3

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Custom Separator

By default, the separator is . but you can customize it:

FlattenResult result = myObject.Flatten(separator: "/");

Produces:

Address/City -> "New York"

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Advanced Flattening Capabilities

Flattening with GlobalConstants.DefaultDotSeparator

If your application uses GlobalConstants.DefaultDotSeparator as the standard separator, you can leverage it:

FlattenResult result = myObject.Flatten(separator: GlobalConstants.DefaultDotSeparator);

Flattening Nested Collections

var obj = new {
    Categories = new[] {
        new { Name = "Tech", Items = new[] { "Laptop", "Phone" } },
        new { Name = "Books", Items = new[] { "Fiction", "Non-Fiction" } }
    }
};

FlattenResult result = obj.Flatten();

Output:

Categories[0].Name -> "Tech"
Categories[0].Items[0] -> "Laptop"
Categories[0].Items[1] -> "Phone"
Categories[1].Name -> "Books"
Categories[1].Items[0] -> "Fiction"
Categories[1].Items[1] -> "Non-Fiction"

Flattening Dictionaries

Dictionaries are also supported and use key-based paths:

var obj = new Dictionary<string, object>
{
    ["User"] = new { Name = "John", Age = 30 },
    ["Settings"] = new { Theme = "Dark" }
};

FlattenResult result = obj.Flatten();

Output:

User.Name -> "John"
User.Age -> 30
Settings.Theme -> "Dark"

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Rehydrating Objects

The FlattenResult allows rehydration into a strongly-typed object:

var rehydrated = (MyClass)result.Rehydrate();

This reconstructs the object with properties populated from the flattened values.

Handling Nested Properties

When rehydrating, intermediate objects and collections are instantiated automatically:

FlattenResult result = Flatten<MyClass>();
MyClass myObject = (MyClass)result.Rehydrate();

FlattenResult and PropertyMapping Documentation

Overview

This document provides an in-depth explanation of the FlattenResult and PropertyMapping classes in DMapper. These classes play a key role in object flattening and property mapping during transformation and serialization processes.

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FlattenResult

Purpose

The FlattenResult class represents the output of an object flattening operation. It provides access to a structured key-value representation of an object and includes functionality to restore the original object structure.

Public Members

Properties

• FlattenedType: The type of the object that was flattened.
• Properties: A dictionary mapping property paths to FlattenedProperty objects.

Constructor

public FlattenResult(Type flattenedType, Dictionary<string, FlattenedProperty> properties)

• flattenedType: Specifies the type of the original object.
• properties: Stores the flattened representation as key-value pairs.

Rehydration

The Rehydrate method reconstructs an object from its flattened representation.

public object Rehydrate(string separator = ".")

• Returns: A new instance of the original type with properties and collections properly instantiated.
• Usage:

FlattenResult result = Flatten<MyClass>();
MyClass rehydratedObject = (MyClass)result.Rehydrate();

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PropertyMapping

Purpose

The PropertyMapping class defines a mapping between a destination property and a chain of source properties, enabling structured object transformation.

Public Members

Properties

• DestinationProperty: The PropertyInfo representing the destination property.
• SourcePropertyChain: An array of PropertyInfo objects representing the property path from the source object.

Example Usage

var mapping = new PropertyMapping
{
    DestinationProperty = typeof(DestinationClass).GetProperty("NestedProperty"),
    SourcePropertyChain = new[]
    {
        typeof(SourceClass).GetProperty("SubObject"),
        typeof(SubObjectClass).GetProperty("Value")
    }
};

This example maps NestedProperty in DestinationClass from SourceClass.SubObject.Value.

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Conclusion

The FlattenResult and PropertyMapping classes are essential for managing object transformation, ensuring that flattened representations maintain structure and allowing for seamless rehydration into objects.

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Conclusion

Flattening is useful for mapping, serialization, and data transformation. Using ObjectFlattener, you can easily convert objects into structured key-value pairs and rehydrate them back into objects when needed. The framework handles collections, nested properties, and dictionaries, making it a powerful tool for handling structured data.

DMapper Fluent API Documentation

Introduction

DMapper's Fluent API provides a powerful and flexible way to define mappings between source and destination objects without relying on attributes. Instead, mappings are configured programmatically using a builder pattern. This approach offers greater control, allowing overrides, multi-source mappings, nested property bindings, and complex binding scenarios.

Getting Started

Installation

Ensure that DMapper and its Fluent API extensions are installed in your project.

using DMapper.Extensions;
using DMapper.Helpers.FluentConfigurations.Contracts;

Defining Mappings

Mappings are defined in destination classes by implementing the IDMapperConfiguration interface. The ConfigureMapping method allows specifying source properties using the builder.Map method.

Basic Mapping

In this example, a simple mapping is defined where properties from SourceFluentTest1 are mapped to DestinationFluentTest1.

public class SourceFluentTest1
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Source { get; set; }
}

public class DestinationFluentTest1 : IDMapperConfiguration
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Destination { get; set; }

    public void ConfigureMapping(IDMapperConfigure builder)
    {
        builder.Map(x => Destination, "Source");
    }
}

Mapping Nested Properties

For mapping nested properties, dot notation can be used.

public class SourceFluentTest2
{
    public string Outer { get; set; }
    public InnerSourceFluent Inner { get; set; } = new InnerSourceFluent();
}

public class InnerSourceFluent
{
    public string InnerProp { get; set; } = "InnerValue";
}

public class DestinationFluentTest2 : IDMapperConfiguration
{
    public string Outer { get; set; }
    public InnerDestFluent Inner { get; set; }

    public void ConfigureMapping(IDMapperConfigure builder)
    {
        builder.Map(x => Outer, "Outer")
            .Map(x => Inner.MyInner, "Inner.InnerProp");
    }
}

public class InnerDestFluent : IDMapperConfiguration
{
    public string MyInner { get; set; }
    public void ConfigureMapping(IDMapperConfigure builder)
    {
        builder.Map(x => MyInner, "InnerProp");
    }
}

Mapping Collections

Collections (lists and arrays) can be mapped similarly.

public class Src1_Fluent
{
    public string Name { get; set; } = "Pesho";
    public List<Src2_Fluent> Src2List { get; set; } = new List<Src2_Fluent> { new Src2_Fluent(), new Src2_Fluent() };
}

public class Src2_Fluent
{
    public int Age { get; set; } = 10;
    public string Name { get; set; } = "John";
}

public class Dest1_Fluent : IDMapperConfiguration
{
    public string Name { get; set; }
    public List<Dest2_Fluent> Src2List { get; set; }

    public void ConfigureMapping(IDMapperConfigure builder)
    {
        builder.Map(x => Name, "Name")
            .Map(x => Src2List, "Src2List");
    }
}

public class Dest2_Fluent : IDMapperConfiguration
{
    public int? Age { get; set; }
    public string Name { get; set; }

    public void ConfigureMapping(IDMapperConfigure builder)
    {
        builder.Map(x => Age, "Age")
            .Map(x => Name, "Name");
    }
}

Multi-Source Mapping

Properties from different source objects can be mapped into a single destination property using multiple candidate keys.

public class SourceFluentTest1_16
{
    public string Name1 { get; set; } = "Source1";
}

public class SourceFluentTest2_16
{
    public string Name2 { get; set; } = "Source2";
}

public class DestinationFluentTest16 : IDMapperConfiguration
{
    public string Name { get; set; }

    public void ConfigureMapping(IDMapperConfigure builder)
    {
        builder.Map(x => Name, "Name1", "Name2");
    }
}

Complex Binding

Complex objects and nested properties can be mapped explicitly.

public class SourceFluentTest3
{
    public string Data { get; set; } = "DataFromSource";
    public NestedSource_Fluent Nested { get; set; } = new NestedSource_Fluent();
}

public class NestedSource_Fluent
{
    public string Info { get; set; } = "NestedInfo";
}

public class DestinationFluentTest3 : IDMapperConfiguration
{
    public string Data { get; set; }
    public NestedDest_Fluent NestedDestination { get; set; }

    public void ConfigureMapping(IDMapperConfigure builder)
    {
        builder.Map(x => Data, "Data")
            .Map(x => NestedDestination.Info, "Nested.Info");
    }
}

public class NestedDest_Fluent
{
    public string Info { get; set; }
}

Handling Circular References

To prevent infinite loops when mapping objects with circular references, mappings should be controlled.

public class SourceFluentTest15
{
    public string Name { get; set; } = "Parent";
    public SourceFluentTest15 Child { get; set; }
}

public class DestinationFluentTest15 : IDMapperConfiguration
{
    public string Name { get; set; }
    public DestinationFluentTest15 Child { get; set; }

    public void ConfigureMapping(IDMapperConfigure builder)
    {
        builder.Map(x => Name, "Name"); // Avoids recursion
    }
}

Conclusion

DMapper's Fluent API provides fine-grained control over mapping definitions, supporting nested properties, collections, multi-source inputs, and circular reference handling. By leveraging programmatic configurations, developers can customize mappings without modifying source models.

Release 2.0.8

BindTo["", useLiteralName]

The [BindTo] attribute is used to decorate destination properties with one or more source property names. By default, if you supply a candidate source name that does not include a dot (used for nested properties), the mapping engine will automatically prepend an effective source prefix to it. In cases where you want to use the provided source name exactly as written (i.e., as a literal), you can enable the literal naming mode.

Overview

The [BindTo] attribute accepts two parameters:

• dest: A comma-separated list of candidate source property names.
• useLiteralName (optional): A boolean flag (default is false) that, when set to true, instructs the mapper to use the provided candidate names exactly as specified without any prefixing.

This option is useful when your source property names are globally unique or when you wish to bypass the default behavior of prefixing candidate names with the current source path.

Default Behavior (Without UseLiteralName)

When you apply the attribute like this:

[BindTo("Name")]
public string FullName { get; set; }

• If the candidate "Name" does not include a dot (.), the mapping engine will automatically prepend the effective source prefix. For example, if the current source prefix is "Person", the engine will look for "Person.Name".

Using UseLiteralName

By setting the useLiteralName parameter to true, the candidate name is used as-is without any automatic prefixing:

[BindTo("Name", useLiteralName: true)]
public string FullName { get; set; }

• Here, the mapper will search for a source property exactly named "Name" regardless of any effective prefix. This is particularly handy if your source property naming does not follow the default nested structure or if it’s already fully qualified.

How It Works Internally

During mapping (for example, in version 6 of the mapping engine), the mapping dictionary is built by examining each destination property. If a destination property is decorated with [BindTo], the engine:

1. Checks for Dot Notation:
   • If the candidate name already contains a dot, it is assumed to be fully qualified.
2. Respects UseLiteralName:
   • If UseLiteralName is set to true, the candidate is used as provided—no prefix is added.
3. Defaults to Relative Names:
   • Otherwise, the effective source prefix is prepended (with a dot separator) to the candidate name.

This behavior ensures that you have the flexibility to define source property mappings either relatively (default) or absolutely (literal).

Practical Example

Imagine you have a destination property that should map to a source property named "Name":

• Relative Mapping (Default):

  // If the effective source prefix is "Employee", the mapper looks for "Employee.Name".
  [BindTo("Name")]
  public string FullName { get; set; }
  

• Literal Mapping:

  // The mapper will directly use "Name" as the source property name.
  [BindTo("Name", useLiteralName: true)]
  public string FullName { get; set; }
  

Summary

• Default Behavior:
  Candidate names without a dot are prefixed with the effective source path.

• Literal Mode (UseLiteralName = true):
  Candidate names are used exactly as provided—ideal for source properties that do not adhere to the destination’s naming conventions.

By understanding and using the UseLiteralName option, you can control how the mapper interprets source property names and tailor the mapping behavior to your specific requirements.

Release 2.0.10

Collection Mapping Documentation

Overview

The Collection Mapping feature in DMapper provides a straightforward and powerful way to map collections, including lists and arrays, from one type to another using the MapTo extension method. It supports automatic mapping of complex types, arrays, and generic collections.

Usage

Mapping Lists and Arrays

You can map any collection implementing IEnumerable to arrays or generic lists:

var sourceList = new List<SourceType> { /* items */ };
var mappedList = sourceList.MapTo<List<DestinationType>>();

var sourceArray = new SourceType[] { /* items */ };
var mappedArray = sourceArray.MapTo<DestinationType[]>();

Example

// Given a source collection:
var source = new List<SourceItem>
{
    new SourceType { Name = "Alpha", Age = 20 },
    new SourceType { Name = "Beta", Age = 25 }
};

// Map to a destination collection:
var result = source.MapTo<List<DestinationType>>();

// Result:
// [{ Name: "Alpha", Age: 20 }, { Name: "Beta", Age: 25 }]

Supported Destination Types

• Arrays: DestinationType[]
• Generic Lists: List<DestinationType>
• Other generic collection types with constructors accepting IEnumerable<T>.

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License

DMapper is licensed under the MIT License.

Happy coding with DMapper! 🚀