Skip to main content

​
Overview

The Jugador (Player) entity represents a football player in the tournament management system. Each player belongs to a team, has a playing position, and wears a unique jersey number within their team.

​
Properties

​
Id
int
Unique identifier for the player.
​
Nombre
string
required
Full name of the player.Validation Rules:
  • Required field (cannot be empty)
  • Must contain only letters and spaces
  • Cannot consist of numbers only
  • Minimum length: 3 characters
  • Maximum length: 50 characters
  • Regex pattern: ^(?![0-9]+$)[a-zA-ZÀ-ÿ\s]+$
Display Name: “Nombre del Jugador”Error Messages:
  • Pattern mismatch: “Valor Incorrecto. Solo se permiten letras”
  • Required: “El nombre del Jugador es obligatorio.”
  • Max length: “El nombre del jugador no puede contener más de 50 caracteres”
  • Min length: “El nombre del jugador no puede contener menos de 3 caracteres”
​
Numero
int
required
Jersey number of the player.Validation Rules:
  • Required field
  • Must contain only numeric values
  • Minimum value: 1
  • Maximum value: 99
  • Regex pattern: ^(?!a-zA-Z+$)[0-9]+$
Display Name: “Número del Jugador”Error Messages:
  • Pattern mismatch: “Valor Incorrecto. Solo se permiten numeros”
  • Required: “El Número del Jugador es obligatorio.”
  • Range: “El Número del Jugador debe estar en un rango entre 1 y 99”
​
Equipo
Equipo?
The team the player belongs to.Nullable: YesRelationship: Many-to-One (Many players belong to one team)Related Entity: Equipo
​
Posicion
Posicion?
The playing position of the player.Nullable: YesRelationship: Many-to-One (Many players can have the same position)Related Entity: Posicion

​
Relationships

The Jugador entity has two important many-to-one relationships:

​
Team (Equipo)

​
Equipo
Equipo
Each player belongs to one team. This is a many-to-one relationship where multiple players are associated with a single team.Navigation Property: EquipoRelated Entity: EquipoCardinality: Many players to one team

​
Position (Posicion)

​
Posicion
Posicion
Each player has one playing position (e.g., Forward, Midfielder, Defender, Goalkeeper). Multiple players can share the same position.Navigation Property: PosicionRelated Entity: PosicionCardinality: Many players to one position

​
Validation Attributes

The Jugador entity uses the following Data Annotations:
  • [Required] - Ensures name and number are mandatory
  • [RegularExpression] - Validates name (letters only) and number (digits only) formats
  • [MaxLength] / [MinLength] - Enforces name character length constraints
  • [Range] - Ensures jersey number is between 1 and 99
  • [Display] - Provides user-friendly display names
  • [DisplayFormat] - Configures empty string handling
The jersey number validation ensures realistic football jersey numbers (1-99), which is standard in most football leagues.

​
Code Examples

​
Entity Definition

using System.ComponentModel.DataAnnotations;

namespace Torneo.App.Dominio
{
    public class Jugador
    {
        public int Id { get; set; }

        [RegularExpression(@"^(?![0-9]+$)[a-zA-ZÀ-ÿ\s]+$", 
            ErrorMessage = "Valor Incorrecto. Solo se permiten letras")]
        [Display(Name = "Nombre del Jugador")]
        [Required(AllowEmptyStrings=false, 
            ErrorMessage = "El nombre del Jugador es obligatorio.")]             
        [MaxLength(50, ErrorMessage = "El nombre del jugador no puede contener más de 50 caracteres")]
        [MinLength(3, ErrorMessage = "El nombre del jugador no puede contener menos de 3 caracteres")] 
        public string Nombre { get; set; }

        [Display(Name = "Número del Jugador")]
        [RegularExpression(@"^(?!a-zA-Z+$)[0-9]+$", 
            ErrorMessage = "Valor Incorrecto. Solo se permiten numeros")]
        [Required(AllowEmptyStrings=false, 
            ErrorMessage = "El Número del Jugador es obligatorio.")]       
        [DisplayFormat(ConvertEmptyStringToNull=false)]
        [Range(1, 99, ErrorMessage = "El Número del Jugador debe estar en un rango entre 1 y 99")]
        public int Numero { get; set; }
        
        public Equipo? Equipo { get; set; } 
        public Posicion? Posicion { get; set; } 
    }
}

​
Creating a Player

var jugador = new Jugador
{
    Nombre = "Lionel Messi",
    Numero = 10,
    Equipo = equipoBarcelona,
    Posicion = posicionDelantero
};

​
Creating Multiple Players

var jugadores = new List<Jugador>
{
    new Jugador 
    { 
        Nombre = "Cristiano Ronaldo", 
        Numero = 7, 
        Posicion = posicionDelantero 
    },
    new Jugador 
    { 
        Nombre = "Sergio Ramos", 
        Numero = 4, 
        Posicion = posicionDefensa 
    },
    new Jugador 
    { 
        Nombre = "Thibaut Courtois", 
        Numero = 1, 
        Posicion = posicionPortero 
    }
};

​
Valid Examples

// Valid player names
Nombre = "Juan Pérez";
Nombre = "María José López";
Nombre = "José Ángel Martínez";

// Valid jersey numbers
Numero = 1;   // Typically goalkeeper
Numero = 10;  // Typical star player number
Numero = 99;  // Maximum allowed

​
Invalid Examples

These examples will fail validation:
// Invalid player names
Nombre = "123";              // Contains only numbers
Nombre = "Player123";        // Contains numbers
Nombre = "AB";               // Less than 3 characters
Nombre = "";                 // Empty (required)

// Invalid jersey numbers
Numero = 0;                  // Below minimum (1)
Numero = 100;                // Above maximum (99)
Numero = -5;                 // Negative number

​
Querying Players

// Get all players on a team
var teamPlayers = equipo.Jugadores;

// Get players by position
var forwards = context.Jugadores
    .Where(j => j.Posicion.Nombre == "Delantero")
    .ToList();

// Get player by jersey number within a team
var player10 = equipo.Jugadores
    .FirstOrDefault(j => j.Numero == 10);

// Get all goalkeepers across all teams
var goalkeepers = context.Jugadores
    .Include(j => j.Posicion)
    .Where(j => j.Posicion.Nombre == "Portero")
    .ToList();

​
Updating Player Information

// Change player's jersey number
jugador.Numero = 7;

// Transfer player to different team
jugador.Equipo = nuevoEquipo;

// Change player position
jugador.Posicion = nuevaPosicion;

​
Jersey Number Uniqueness

While the entity validation ensures numbers are between 1-99, additional business logic may be needed to ensure jersey numbers are unique within a team.
// Example: Checking for unique jersey number within team
public bool IsNumeroUniqueInTeam(Jugador jugador)
{
    return !jugador.Equipo.Jugadores
        .Any(j => j.Id != jugador.Id && j.Numero == jugador.Numero);
}

​
Common Use Cases

​
Squad Management

// Get team roster grouped by position
var roster = equipo.Jugadores
    .GroupBy(j => j.Posicion.Nombre)
    .Select(g => new 
    { 
        Posicion = g.Key, 
        Jugadores = g.ToList() 
    });

​
Player Statistics

// Count players by position
var playerCountByPosition = context.Jugadores
    .GroupBy(j => j.Posicion.Nombre)
    .Select(g => new 
    { 
        Posicion = g.Key, 
        Count = g.Count() 
    });

​
Database Mapping

The Jugador entity is mapped to a database table with the same name. The Id property serves as the primary key and is auto-generated.Foreign keys are created for:
  • Equipo relationship (EquipoId)
  • Posicion relationship (PosicionId)

Build docs developers (and LLMs) love

Get started for freeTalk to us