BlogDoFT.Libs.EntityFramework.CodeGenerator 10.1.0

BlogDoFT.Libs.EntityFramework.CodeGenerator

A Roslyn Source Generator that reads filter DTOs annotated with BlogDoFT.Libs.EntityFramework.CodeGenerator.Abstractions.GeneratePredicateAttribute<TEntity> and emits:

• ToPredicate() → Expression<Func<TEntity, bool>>
• HasFilter() → bool

The generated predicates are provider-aware:

• On PostgreSQL (when Npgsql.EntityFrameworkCore.PostgreSQL is referenced), string filters with % use ILIKE.
• On other providers, string filters with % use EF.Functions.Like.
• No reflection is used; the generator detects NpgsqlDbFunctionsExtensions.ILike at compile-time.

Target Framework: netstandard2.0 (Analyzer-friendly)
C# Language Version: latest

Installation

Install the NuGet package:

dotnet add package BlogDoFT.Libs.EntityFramework.CodeGenerator.Generators

The application must also reference BlogDoFT.Libs.EntityFramework.CodeGenerator.Abstractions.

How it works

1. The generator scans the compilation for classes annotated with [GeneratePredicate<TEntity>];
2. It validates the DTO is partial; otherwise it reports PG001 (error).
3. It discovers filterable properties annotated with:
   • StringFilterAttribute
   • NumericFilterAttribute
   • TemporalFilterAttribute
   • BooleanFilterAttribute
4. It detects at compile-time whether NpgsqlDbFunctionsExtensions.ILike(DbFunctions, string, string) is available:
   • If present → emits code that builds expression calls to ILIKE
   • If absent → emits code that falls back to LIKE
5. It generates partial members HasFilter() and ToPredicate() into the same DTO namespace and type.

Example end-to-end

Entity

namespace Domain;

public class UserRecord
{
    public Guid Id { get; set; }
    public string Name { get; set; } = "";
    public string Email { get; set; } = "";
    public int Age { get; set; }
    public DateTime CreatedAt { get; set; }
    public bool Active { get; set; }
}

Filter DTO

using BlogDoFT.Libs.EntityFramework.CodeGenerator.Abstractions;

[GeneratePredicate<Domain.UserRecord>]
public partial class UserFilterDto
{
    [StringFilter(TargetProperty = nameof(Domain.UserRecord.Name), Order = 1)]
    public string? Name { get; init; }

    [StringFilter(TargetProperty = nameof(Domain.UserRecord.Email), Order = 2)]
    public string? Email { get; init; }

    [NumericFilter(TargetProperty = nameof(Domain.UserRecord.Age), Operator = ComparisonOperator.GreaterThanOrEqual)]
    public int? MinimumAge { get; init; }

    [TemporalFilter(TargetProperty = nameof(Domain.UserRecord.CreatedAt), Operator = ComparisonOperator.LessThanOrEqual)]
    public DateTime? CreatedUntil { get; init; }

    [BooleanFilter(TargetProperty = nameof(Domain.UserRecord.Active))]
    public bool? Active { get; init; }
}

Query with EF Core

var filter = new UserFilterDto
{
    Name = "%ann%",
    MinimumAge = 18,
    Active = true
};

var predicate = filter.ToPredicate();

var users = await db.Set<UserRecord>()
    .Where(predicate)
    .ToListAsync();

String pattern rules

• If the value does not contain %, the generator emits equality (field == value).
• If the value contains %, the generator emits a database pattern using:
  • ILIKE (PostgreSQL with Npgsql)
  • LIKE (fallback on other providers) This way you keep multi-database compatibility while getting case-insensitive matching on PostgreSQL.

If you want to support * as a wildcard in input, normalize it to % in your DTO before calling ToPredicate().

Requirements

• BlogDoFT.Libs.EntityFramework.CodeGenerator.Abstractions must be referenced by the app
• C# 11+ (generic attributes) in the app project
• EF Core 6/7/8+

Troubleshooting

The generated methods are missing

• Ensure the DTO is marked as partial;
• Ensure the app references BlogDoFT.Libs.EntityFramework.CodeGenerator.Abstractions and the generator as Analyzer.
• Clean and rebuild the solution.

I want to see SQL logs

Install and configure console logging:

<PackageReference Include="Microsoft.Extensions.Logging.Console" />

services.AddLogging(b =>
{
    b.ClearProviders();
    b.AddSimpleConsole();
    b.AddFilter("Microsoft.EntityFrameworkCore.Database.Command", LogLevel.Information);
});

Add in your DbContext Options:

options
    .UseLoggerFactory(loggerFactory)
    .EnableSensitiveDataLogging()
    .EnableDetailedErrors();

Versioning

Starting with v10.0.0, this library's version numbering follows the major version of the .NET runtime it targets. For example, this version is compatible with .NET 10, so the major version is 10 — this explains the jump from the previous 1.x version series.