.Net 7 (Preview 4) - Minimal API Filters

https://dotnet.microsoft.com/en-us/download/dotnet/7.0

https://github.com/mohamadlawand087/MinimalApi-JWT

<Project Sdk="Microsoft.NET.Sdk.Web">  <PropertyGroup>    <TargetFramework>net7.0</TargetFramework>    <Nullable>enable</Nullable>    <ImplicitUsings>enable</ImplicitUsings>    <LangVersion>preview</LangVersion>  </PropertyGroup>  <ItemGroup>    <PackageReference Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="7.0.0-preview.4.22229.2" />    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="7.0.0-preview.4.22229.2">      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>      <PrivateAssets>all</PrivateAssets>    </PackageReference>    <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="7.0.0-preview.4.22229.2" />    <PackageReference Include="Swashbuckle.AspNetCore" Version="6.2.3" />  </ItemGroup></Project>

dotnet run

app.MapPost("/items",  [Authorize] async (ApiDbContext db, Item item) => {    if( await db.Items.FirstOrDefaultAsync(x => x.Id == item.Id) != null)    {        return Results.BadRequest();    }    db.Items.Add(item);    await db.SaveChangesAsync();    return Results.Created( $"/Items/{item.Id}",item);}).AddFilter((ctx, next) => async (context) =>{    return  CheckIncomingObj(context)  == false ? Results.BadRequest("Invalid parameters") : await next(context);});bool? CheckIncomingObj(RouteHandlerInvocationContext context) {    if (context.Parameters[1] == null)         return false;    if (context.Parameters[1] is not Item param)        return false;    return IsValidItem(param);}bool IsValidItem(Item item){    if (item.Title.Length > 1 && item.Id > 0)        return true;    return false;}

namespace TodoApi.Filters;public class ValidationFilter<T> : IRouteHandlerFilter where T : class{    public async ValueTask<object?> InvokeAsync(RouteHandlerInvocationContext context, RouteHandlerFilterDelegate next)    {        var param = context.Parameters.FirstOrDefault(x => x?.GetType() == typeof(T));        if(param is null)        {            return Results.BadRequest();        }        if (param is Item)        {            var validationResult = IsValidItem(param as Item);            if(!validationResult)            {                return Results.BadRequest("Invalid parameters.");            }        }        // before the endpoint call        var result = await next(context);        // after endpoint call        return result;    }    bool IsValidItem(Item? item)    {        if (item == null)            return false;        if (item.Title.Length > 1 && item.Id > 0)            return true;        return false;    }}

app.MapPost("/items", [Authorize] async (ApiDbContext db, Item item) =>{    if (await db.Items.FirstOrDefaultAsync(x => x.Id == item.Id) != null)    {        return Results.BadRequest();    }    db.Items.Add(item);    await db.SaveChangesAsync();    return Results.Created($"/Items/{item.Id}", item);}).AddFilter<ValidationFilter<Item>>();