Dotnet Output

A .NET helper library that standardizes process and data outputs, provides a paginated output container, and includes IQueryable pagination extension methods (synchronous & asynchronous).

Contents

• Project overview
• Classes
  • ProcessOutput
  • DataOutput
  • PaginatedOutput
  • CustomException
  • PaginatedOutputExtensions (extension methods)
• Usage examples
• Add as a Git submodule and reference
• Mermaid class diagram
• Notes

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Overview

ArturRios.Output provides lightweight types to represent the result of operations in a consistent way. Typical use cases:

• Return success/failure information together with messages and errors
• Return typed data payloads with fluent helpers
• Return paginated list results and help paginate IQueryable sources (works with EF Core or in-memory LINQ)

The library has no external runtime dependencies apart from Microsoft.EntityFrameworkCore when you call the EF-aware PaginateAsync extension (the extension is written to work with both IQueryables that support async and ones that don't).

Classes

• ProcessOutput

  • Purpose: Base container for operation results. Captures messages, errors, timestamp and a convenience Success flag.
  • Key members:
    • List<string> Messages { get; }
    • List<string> Errors { get; }
    • DateTime Timestamp { get; } (UTC)
    • bool Success { get; } (true when no errors)
    • Fluent helpers: WithError, WithErrors, WithMessage, WithMessages
    • Add helpers: AddError, AddErrors, AddMessage, AddMessages
    • Static factory: ProcessOutput.New

• DataOutput<T> : ProcessOutput

  • Purpose: Holds a typed data payload plus everything ProcessOutput provides.
  • Key members:
    • T? Data { get; protected set; }
    • Fluent API: WithData(T), WithError(string), WithErrors(IEnumerable<string>), WithMessage(string), WithMessages(IEnumerable<string>)
    • Static factory: DataOutput<T>.New

• PaginatedOutput<T> : DataOutput<List<T>>

  • Purpose: Represents a paginated result set containing List<T> as the payload.
  • Key members:
    • int PageNumber { get; set; }
    • int PageSize { get; } (derived from Data?.Count)
    • int TotalItems { get; set; }
    • int TotalPages { get; } (computed as Ceil(TotalItems / PageSize))
    • Helpers to build: WithPagination(int pageNumber, int totalItems), WithData(List<T>), WithData(T), WithEmptyData(), AddItem(T), AddItems(IEnumerable<T>)
    • Fluent WithMessage / WithError overloads preserved.
    • Static factory: PaginatedOutput<T>.New

• CustomException (abstract)

  • Purpose: Base exception type wrapping an array of messages. Derive from it to create domain-specific exceptions that carry multiple messages.
  • Key members:
    • Constructor that accepts string[] messages and builds the base Exception message by joining them
    • string[] Messages { get; }

• PaginatedOutputExtensions (static)

  • Purpose: Extension methods for IQueryable<T> to paginate a query and return a PaginatedOutput<T>.
  • Methods:
    • Task<PaginatedOutput<T>> PaginateAsync<T>(this IQueryable<T> query, int pageNumber, int pageSize, Expression<Func<T, object?>>? orderBy = null, CancellationToken cancellationToken = default)
      • Uses EF Core async if the query provider supports IAsyncQueryProvider; otherwise falls back to synchronous ToList().
    • PaginatedOutput<T> Paginate<T>(this IQueryable<T> query, int pageNumber, int pageSize, Expression<Func<T, object?>>? orderBy = null)
      • Synchronous variant. When provided, orderBy is applied.

Usage examples

Basic (ProcessOutput / DataOutput)

using ArturRios.Output;

// Simple success response with a message
var p = ProcessOutput.New.WithMessage("Operation completed");

// Data output
var d = DataOutput<int>.New
    .WithData(42)
    .WithMessage("Value computed");

if (!d.Success) {
    // inspect d.Errors
}

Paginated example (synchronous)

using ArturRios.Output;

IQueryable<MyEntity> query = ...; // your LINQ or EF Core query
int pageNumber = 1;
int pageSize = 20;

var page = query.Paginate(pageNumber, pageSize, e => e.CreatedAt);
// page is PaginatedOutput<MyEntity>
var items = page.Data; // List<MyEntity>

Paginated example (async, EF Core)

using ArturRios.Output;

var page = await dbContext.Set<MyEntity>()
    .Where(e => e.IsActive)
    .PaginateAsync(pageNumber: 2, pageSize: 50, orderBy: e => e.CreatedAt, cancellationToken: ct);

var items = page.Data; // List<MyEntity>

How to use in your project

Add as a Git submodule and reference the project in your solution:

# from your solution repository root
git submodule add <git-url-of-this-repo> external/dotnet-output
git submodule update --init --recursive

# then add the csproj to your solution (adjust path)
dotnet sln add external/dotnet-output/src/ArturRios.Output.csproj

This keeps the library as a normal project dependency and allows debugging into its code.

API notes & gotchas

• PaginatedOutput.PageSize is derived from the returned Data.Count (i.e., the number of items in the current page). TotalItems is intended to be the total number of items across all pages. TotalPages is computed as Ceiling(TotalItems / PageSize).

Class diagram

Below is a mermaid class diagram representing the public classes in this project. You can paste this into any mermaid-enabled renderer (for example GitHub markdown with mermaid enabled, or live editors).

classDiagram
    class ProcessOutput {
        +Messages: List_string
        +Errors: List_string
        +Timestamp: DateTime
        +Success: bool
    }

    class DataOutput_T {
        +Data: T_optional
    }

    class PaginatedOutput_T {
        +PageNumber: int
        +PageSize: int
        +TotalItems: int
        +TotalPages: int
    }

    class CustomException {
        +Messages: string_array
    }

    class PaginatedOutputExtensions {
        +PaginateAsync()
        +Paginate()
    }

    DataOutput_T --|> ProcessOutput
    PaginatedOutput_T --|> DataOutput_T
    PaginatedOutputExtensions ..> PaginatedOutput_T: uses

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Build, test and publish

Use the official .NET CLI to build, test and publish the project and Git for source control. If you want, optional helper toolsets I built to facilitate these tasks are available:

• Dotnet Tools
• Python Dotnet Tools

Both of them are compatible with this project structure. Installation and usage instructions are available in their respective repositories.

Contributing

Contributions are welcome. For small fixes a PR with tests and a few usage examples is ideal.

Legal Details

This project is licensed under the MIT License. A copy of the license is available at LICENSE in the repository.

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