Custom Model Binding in ASP.NET Core MVC
Custom model binding is the process of intercepting the ASP.NET Core MVC standard model binding function and supplying custom logic to convert request data into parameters for action methods.
Deepak Talwar
0
22
This Article helps to understand the concept of Custom Model Binding in ASP.NET Core MVC
Custom Model Binding helps, when you have special data or formats that the built-in model binders don't support
Step 1: Create the Custom Model Binder:
Implement the IModelBinder interface. The BindModelAsync method must be implemented in order to use IModelBinder interface.
using Microsoft.AspNetCore.Mvc.ModelBinding;
namespace WebApplication3.ModelBinders
{
public class QueryStringToArrayModelBinder : IModelBinder
{
public Task BindModelAsync(ModelBindingContext bindingContext)
{
try
{
var queryString = bindingContext.HttpContext.Request.Query;
var UserIds = queryString["userIds"].ToString();
if (string.IsNullOrEmpty(UserIds))
{
return Task.CompletedTask;
}
var values = UserIds.Split(',').Select(int.Parse).ToList();
bindingContext.Result = ModelBindingResult.Success(values);
return Task.CompletedTask;
}
catch (Exception ex)
{
bindingContext.ModelState.AddModelError("Error", "Received Input cannot be parsed");
return Task.CompletedTask;
}
}
}
}
Step 2: Create a Model Binder Provider:
Implement the IModelBinderProvider interface. this helps ASP.NET to determine when to use your custom binder.
using Microsoft.AspNetCore.Mvc.ModelBinding;
namespace WebApplication3.ModelBinders
{
public class QueryStringToArrayModelBinderProvider : IModelBinderProvider
{
public IModelBinder GetBinder(ModelBinderProviderContext context)
{
if (context.Metadata.ModelType == typeof(List<int>))
{
return new QueryStringToArrayModelBinder();
}
return null;
}
}
}
Step 3: Register Your Custom Binder:
Register your custom binder to the MVC options during application startup.
// Register in Program.cs file
builder.Services.AddControllersWithViews(options =>
{
options.ModelBinderProviders.Insert(0, new QueryStringToArrayModelBinderProvider());
});
Step 4: Using Custom Binder:
namespace WebApplication3.Controllers
{
public class StudentController : Controller
{
public IActionResult Detail([ModelBinder(typeof(QueryStringToArrayModelBinder))] List<int> Ids)
{
return Ok(Ids);
}
}
}
Step 5: Run
/student/detail?Ids=10,20,30
