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Overview

The Prestamo interface represents a book loan in the virtual library system. It tracks loan requests, approvals, rejections, and returns.

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Interface Definition

import { Libro } from './libro';

export interface Prestamo {
  id: number;
  fechaSolicitud: string;
  fechaDevolucion?: string;
  estado: 'PENDIENTE' | 'APROBADO' | 'RECHAZADO';
  libro: Libro;
  usuario: any; // Usuario completo desde Spring Boot
}

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Properties

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Basic Properties

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id
number
required
Unique identifier for the loan. Auto-generated by the backend.
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fechaSolicitud
string
required
The date and time when the loan was requested. Typically in ISO 8601 format (e.g., "2024-03-15T10:30:00").
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fechaDevolucion
string
Optional return date for the book. Set when the book is returned or when an approved loan has a due date.
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estado
'PENDIENTE' | 'APROBADO' | 'RECHAZADO'
required
The current status of the loan request:
  • PENDIENTE: Loan request is pending approval
  • APROBADO: Loan has been approved by an administrator
  • RECHAZADO: Loan request has been rejected

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Relationships

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libro
Libro
required
The book being loaned. See Libro interface for details.
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usuario
any
required
The user who requested the loan. This is the complete user object returned from the Spring Boot backend.

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Estado Enum

The estado property uses a string literal union type with three possible values: 
type EstadoPrestamo = 'PENDIENTE' | 'APROBADO' | 'RECHAZADO';

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Estado Values

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PENDIENTE
string
Initial state when a user requests a book loan. Awaiting administrator approval.
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APROBADO
string
The loan has been approved by an administrator. The book is now marked as unavailable.
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RECHAZADO
string
The loan request has been rejected by an administrator.

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Usage Examples

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Requesting a Loan (User)

import { PrestamoService } from './core/services/prestamo';

const libroId = 1;

this.prestamoService.solicitar(libroId).subscribe({
  next: (response) => {
    console.log('Loan requested:', response);
    // Response is typically a success message
  },
  error: (err) => {
    console.error('Loan request failed:', err);
  }
});

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Viewing All Loans (Admin)

import { Prestamo } from './core/models/prestamo';

this.prestamoService.getAll().subscribe({
  next: (prestamos: Prestamo[]) => {
    prestamos.forEach(prestamo => {
      console.log(`Loan #${prestamo.id}:`);
      console.log(`  Book: ${prestamo.libro.titulo}`);
      console.log(`  Status: ${prestamo.estado}`);
      console.log(`  Requested: ${prestamo.fechaSolicitud}`);
      if (prestamo.fechaDevolucion) {
        console.log(`  Return date: ${prestamo.fechaDevolucion}`);
      }
    });
  },
  error: (err) => console.error('Error fetching loans:', err)
});

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Viewing User’s Own Loans

this.prestamoService.getMisPrestamos().subscribe({
  next: (misPrestamos: Prestamo[]) => {
    const pendientes = misPrestamos.filter(p => p.estado === 'PENDIENTE');
    const aprobados = misPrestamos.filter(p => p.estado === 'APROBADO');
    const rechazados = misPrestamos.filter(p => p.estado === 'RECHAZADO');
    
    console.log(`Pending: ${pendientes.length}`);
    console.log(`Approved: ${aprobados.length}`);
    console.log(`Rejected: ${rechazados.length}`);
  }
});

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Approving a Loan (Admin)

const prestamoId = 5;

this.prestamoService.aprobar(prestamoId).subscribe({
  next: (response) => {
    console.log('Loan approved:', response);
    // The book's disponible status will be updated to false
  },
  error: (err) => {
    console.error('Approval failed:', err);
  }
});

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Rejecting a Loan (Admin)

const prestamoId = 6;

this.prestamoService.rechazar(prestamoId).subscribe({
  next: (response) => {
    console.log('Loan rejected:', response);
  },
  error: (err) => {
    console.error('Rejection failed:', err);
  }
});

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Filtering Loans by Status

import { Prestamo } from './core/models/prestamo';

getPrestamosByEstado(estado: 'PENDIENTE' | 'APROBADO' | 'RECHAZADO') {
  this.prestamoService.getAll().subscribe({
    next: (prestamos: Prestamo[]) => {
      const filtered = prestamos.filter(p => p.estado === estado);
      console.log(`${filtered.length} loans with status ${estado}`);
      return filtered;
    }
  });
}

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Checking Book Availability Before Requesting

import { Libro } from './core/models/libro';

solicitarPrestamo(libro: Libro) {
  if (!libro.disponible) {
    console.error('Book is not available for loan');
    return;
  }
  
  this.prestamoService.solicitar(libro.id).subscribe({
    next: (response) => {
      console.log('Loan requested successfully');
    },
    error: (err) => {
      console.error('Error:', err);
    }
  });
}

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Template Usage

<!-- Admin: Loan management table -->
<table>
  <thead>
    <tr>
      <th>ID</th>
      <th>Book</th>
      <th>User</th>
      <th>Request Date</th>
      <th>Status</th>
      <th>Actions</th>
    </tr>
  </thead>
  <tbody>
    <tr *ngFor="let prestamo of prestamos">
      <td>{{ prestamo.id }}</td>
      <td>{{ prestamo.libro.titulo }}</td>
      <td>{{ prestamo.usuario.username }}</td>
      <td>{{ prestamo.fechaSolicitud | date }}</td>
      <td>
        <span [class]="'badge-' + prestamo.estado.toLowerCase()">
          {{ prestamo.estado }}
        </span>
      </td>
      <td>
        <button 
          *ngIf="prestamo.estado === 'PENDIENTE'"
          (click)="aprobar(prestamo.id)">
          Aprobar
        </button>
        <button 
          *ngIf="prestamo.estado === 'PENDIENTE'"
          (click)="rechazar(prestamo.id)">
          Rechazar
        </button>
      </td>
    </tr>
  </tbody>
</table>

<!-- User: My loans list -->
<div *ngFor="let prestamo of misPrestamos" class="loan-card">
  <h3>{{ prestamo.libro.titulo }}</h3>
  <p>Requested: {{ prestamo.fechaSolicitud | date:'short' }}</p>
  <p *ngIf="prestamo.fechaDevolucion">
    Return by: {{ prestamo.fechaDevolucion | date:'short' }}
  </p>
  <span class="status" [ngClass]="{
    'pending': prestamo.estado === 'PENDIENTE',
    'approved': prestamo.estado === 'APROBADO',
    'rejected': prestamo.estado === 'RECHAZADO'
  }">
    {{ prestamo.estado }}
  </span>
</div>

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Component Implementation Example

import { Component, OnInit } from '@angular/core';
import { PrestamoService } from './core/services/prestamo';
import { Prestamo } from './core/models/prestamo';

@Component({
  selector: 'app-prestamo-list',
  templateUrl: './prestamo-list.component.html'
})
export class PrestamoListComponent implements OnInit {
  prestamos: Prestamo[] = [];
  loading = false;

  constructor(private prestamoService: PrestamoService) {}

  ngOnInit() {
    this.loadPrestamos();
  }

  loadPrestamos() {
    this.loading = true;
    this.prestamoService.getAll().subscribe({
      next: (data) => {
        this.prestamos = data;
        this.loading = false;
      },
      error: (err) => {
        console.error('Error loading loans:', err);
        this.loading = false;
      }
    });
  }

  aprobar(id: number) {
    this.prestamoService.aprobar(id).subscribe({
      next: () => {
        console.log('Loan approved');
        this.loadPrestamos(); // Reload list
      },
      error: (err) => console.error('Error:', err)
    });
  }

  rechazar(id: number) {
    this.prestamoService.rechazar(id).subscribe({
      next: () => {
        console.log('Loan rejected');
        this.loadPrestamos(); // Reload list
      },
      error: (err) => console.error('Error:', err)
    });
  }

  getPendingCount(): number {
    return this.prestamos.filter(p => p.estado === 'PENDIENTE').length;
  }
}
  • Libro - Book interface referenced by Prestamo
  • Autor - Author interface (referenced through Libro)
  • Genero - Genre interface (referenced through Libro)

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Business Rules

When a loan is approved (APROBADO), the associated book’s disponible property is automatically set to false by the backend.
Users can only request loans for books where libro.disponible === true. The backend will reject requests for unavailable books.
The fechaSolicitud is automatically set by the backend when the loan is created. You don’t need to provide it when requesting a loan.

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Notes

Consider implementing date formatting utilities to display fechaSolicitud and fechaDevolucion in a user-friendly format.
The usuario field contains the complete user object from Spring Boot. The exact structure depends on your backend User model.

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