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README.md

HybridModelBinding

For those who want the utmost flexibility in model binding.

The hybrid approach differs from traditional model binding since you get to work with both IModelBinder and IValueProvider. This means your model can first get bound with data from the body of a request, and then get updated with data from route or querystring-attributes (in that order). This has the most benefit for users who prefer to have one-model for their request representations.

Examples

ASP.NET Core 3.1

dotnet add package HybridModelBinding

Startup.cs

// Boilerplate...

public void ConfigureServices(IServiceCollection services)
{
    // Add framework services.
    services
        .AddMvc()

        /**
         * This will also register a MVC-convention to auto-apply hybrid-binding behavior when a controller-action has a single parameter.
         * There are additional rules that get enforced to make sure the class is instantiable before applying this convention.
         */
        .AddHybridModelBinder(options =>
        {
            /**
             * This is optional and overrides internal ordering of how binding gets applied to a model that doesn't have explicit binding-rules.
             * Internal ordering is: body => form-values => route-values => querystring-values => header-values
             */
            options.FallbackBindingOrder = new[] { Source.QueryString, Source.Route };
        });
}

Model

using HybridModelBinding;

[HybridBindClass(defaultBindingOrder: new[] { Source.Header, Source.Body, Source.Form, Source.QueryString, Source.Route })]
public class IndexModel
{
    // Binding will result from ordering specified at the class-level.
    public int? Age { get; set; }

    /// <summary>
    /// For this specific source, we want to bind to a header-key of `X-Name`.
    /// Additionally, this has higher-precedence when looking for a binding-source.
    /// </summary>
    [HybridBindProperty(Source.Header, "X-Name")]

    /// <summary>
    /// These are bound using the source-key of `Name`.
    /// </summary>
    [HybridBindProperty(new[] { Source.Body, Source.Form, Source.QueryString, Source.Route })]
    public string Name { get; set; }
}
HybridBindClass

This attribute is optional. It allows specifying default-ordering when a property is not decorated with HybridBindProperty. This will override FallbackBindingOrder.

HybridBindProperty

This attribute is optional. It will override HybridBindClass and FallbackBindingOrder. It also allows specifying order. This is implicitly set based on the line-number of the attribute. It can also be explicitly set to avoid confusion:

[HybridBindProperty(Source.Header, "X-Name", order: 5)]
[HybridBindProperty(new[] { Source.Body, Source.Form, Source.QueryString, Source.Route }, order: 10)]
public string Name { get; set; }

Declaring multiple attributes on the same line may cause unpredictable results and should be avoided (unless using explicit ordering):

[HybridBindProperty(Source.Header, "X-Name")][HybridBindProperty(new[] { Source.Body, Source.Form, Source.QueryString, Source.Route })]
public string Name { get; set; }

This way is also valid, but may look odd depending whether you read lists top-bottom or bottom-top. In this case, the Source.Body...-attribute is given higher priority.

[HybridBindProperty(Source.Header, "X-Name", order: 10)]
[HybridBindProperty(new[] { Source.Body, Source.Form, Source.QueryString, Source.Route }, order: 5)]
public string Name { get; set; }
IHybridBoundModel

Maybe you want to see how a property received its value. If your model implements IHybridBoundModel, this will give you what you seek. This is optional and not required for everything else to work.

public class IndexModel : IHybridBoundModel
{
    public int? Age { get; set; }

    [HybridBindProperty(Source.Header, "X-Name")]
    [HybridBindProperty(new[] { Source.Body, Source.Form, Source.QueryString, Source.Route })]
    public string Name { get; set; }

    /**
     * Key is the property-name
     * Value is the source of the binding
     */
    public IDictionary<string, string> HybridBoundProperties { get; } = new Dictionary<string, string>();
}

Controller

[HttpGet]
[Route("{age?}/{name?}")]
public IActionResult Index(IndexModel model)
{ }

/**
 * This action needs to declare `[FromHybrid]` since the registered convention won't hook it up to the library.
 * Without the parameter-attribute, default .NET behavior will get applied—even if your model is decorated with hybrid-attributes.
 */
[HttpGet]
[Route("{age?}/{name?}")]
public IActionResult IndexAlternate(int age, [FromHybrid]IndexModel model)
{ }
FromHybrid

This attribute is optional if the action only contains one, class-parameter. When used, however, also has the ability to specify default-ordering when a property is not decorated with HybridBindProperty. This will override FallbackBindingOrder and HybridBindClass. This is useful if an action has different requirements than other actions using the same model:

[HttpGet]
[Route("{age?}/{name?}")]
public IActionResult IndexAlternate([FromHybrid(new[] { Source.QueryString, Source.Route })]IndexModel model)
{ }

View

<h3>Age: @(Model.Age.HasValue ? Model.Age.ToString() : "N/A")</h3>
<h3>Name: @(string.IsNullOrEmpty(Model.Name) ? "N/A" : Model.Name)</h3>

Results

Based on the setup above, here is how various URIs will get parsed/rendered:

/

<h3>Age: N/A</h3>
<h3>Name: N/A</h3>

/10

<h3>Age: 10</h3>
<h3>Name: N/A</h3>

/10/Bill

<h3>Age: 10</h3>
<h3>Name: Bill</h3>

/10/Bill?age=20

<h3>Age: 20</h3>
<h3>Name: Bill</h3>

/10/Bill?age=20&name=Boga

<h3>Age: 20</h3>
<h3>Name: Bill</h3> <!--note how the querystring does not get bound since the route comes first in the [From...] ordering-->

Example using headers and alternate-naming

curl -X GET \
  http://localhost/10/Bill?name=Boga \
  -H 'X-Name: Billy'
<h3>Age: 20</h3>
<h3>Name: Billy</h3>

About

Provides the ability to bind models using both ModelBinder and ValueProvider in ASP.NET Core.

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