ExpressWalker provides a generic way to examine and change any object graph in fashion similar to "Visitor Pattern". You can build generic hierarchy composition (visitor) capable to "visit" and change any object's property, basing on configuration. Uses reflection only while building a visitor and relies purely on expression trees while visiting objects. That's why IT IS WAY FASTER than custom solutions usually built with reflection.

It is optionally protected from circular references so you can avoid StackOverflowException easily. Provides fluent API while building a visitor which increases code readability in terms of recognizing the hierarchy being built right away from the code. Some of functionalities: are visiting properties by matching owner type and name (or only type), visiting through items in collecitons, specifying depth, custom expression for changing property value, cloning etc.

//example 1 - IVisitor that visits properties by property names and/or types (start from TypeWalker class):

 var typeVisitor = TypeWalker<Parent>.Create()
                 .ForProperty<Parent, string>(p => p.TestString1, (old, met) => old + met)
                 .ForProperty<Child, DateTime>(p => p.TestDate1, (old, met) => old.AddYears(10))
                 .ForProperty<CommonType>((old, met) => new CommonType { CommonString = "..." })

 var parentClone = new Parent();
 var propertyValues = new HashSet<PropertyValue>()
 typeVisitor.Visit(parentObject, parentClone, 10, new InstanceGuard(), propertyValues);
//example 2 - IVisitor that visits properties by explicit configuration (start from ManualWalker class):

 var manualVisitor = ManualWalker.Create<A1>()
                                   .Property<A1, DateTime>(a1 => a1.A1Date, (va1, met) => va1.AddYears(10))
                                   .Element<A1, B1>(a1 => a1.B1, b1 =>
                                           b1.Property<B1, string>(x => x.B1Name, (vb1, met) => vb1 + "Test2"))
                                   .Collection<A1, B2>(a1 => a1.B2List, b2 => b2
                                           .Property<B2, DateTime>(x => x.B2Date, (vb2, met) => vb2.AddYears(10)))

 var parentClone = new A1();
 var propertyValues = new HashSet<PropertyValue>()
 manualVisitor.Visit(parentObject, parentClone, 10, new InstanceGuard(), propertyValues);

//Paremeter 'met' in expressions above is optional metadata object set in design-time.
//It can be set by [VisitorMetadata] property attribute in visited class.
//e.g. in example above, there is [VisitorMetadata("AnyString")] on property Parent.TestString1.

Many thanks to Francisco José Rey Gozalo for contributing with ideas and solutions.

There is a newer version of this package available.
See the version list below for details.
Install-Package ExpressWalker -Version
dotnet add package ExpressWalker --version
<PackageReference Include="ExpressWalker" Version="" />
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add ExpressWalker --version
The NuGet Team does not provide support for this client. Please contact its maintainers for support.
#r "nuget: ExpressWalker,"
For F# scripts that support #r syntax, copy this into the source code to reference the package.

Release Notes

More refinded and comprihensive unit tests are added. Visits based on depth are tested and fixed.


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Version History

Version Downloads Last updated 672 4/1/2018 618 9/10/2016 571 9/8/2016 570 9/7/2016 569 9/7/2016 576 8/17/2016 564 8/17/2016 590 8/16/2016 570 8/16/2016 569 8/9/2016 596 8/7/2016 550 8/7/2016 570 8/7/2016 555 8/7/2016 565 8/4/2016 587 8/3/2016 583 8/3/2016 595 8/3/2016 582 8/3/2016
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