Code Explainers

Code explainers tagged #dependency-injection

python 
from fastapi import APIRouter, BackgroundTasks, Depends, HTTPException, status
from pydantic import BaseModel, EmailStr
from sqlalchemy.orm import Session
 

Building a signup endpoint in FastAPI

dependency-injection request-validation background-tasks
Intermediate 8 steps
php 
<?php
 
namespace App\Providers;
 

Subdomain multi-tenancy routing in Laravel

multi-tenancy service-container route-binding
Advanced 7 steps
java 
@RestController
@RequestMapping("/api/products")
public class ProductSearchController {
 

Binding collection query params in Spring

rest-api query-parameters dependency-injection
Intermediate 6 steps
typescript 
import { Component, signal } from '@angular/core';
import { CommonModule } from '@angular/common';
import { RevenueChartComponent } from './revenue-chart.component';
import { ReportService, RevenueReport } from './report.service';

Deferred chart loading with @defer in Angular

lazy-loading signals dependency-injection
Intermediate 8 steps
typescript 
import { Injectable, inject } from '@angular/core';
import { PreloadingStrategy, Route } from '@angular/router';
import { Observable, of, Subject } from 'rxjs';
import { filter, switchMap, take } from 'rxjs/operators';

A hover-triggered preloading strategy in Angular

lazy-loading rxjs preloading
Advanced 8 steps
typescript 
import { Injectable, inject } from '@angular/core';
import { MatDialog } from '@angular/material/dialog';
import { Observable, of } from 'rxjs';
import { switchMap } from 'rxjs/operators';

A reusable confirmation dialog service in Angular

dependency-injection observables dialog
Intermediate 6 steps
typescript 
import { Module } from '@nestjs/common';
import { ConfigModule, ConfigService } from '@nestjs/config';
import { createClient, RedisClientType } from 'redis';
 

Provide a Redis client with a NestJS factory

dependency-injection async-factory redis
Intermediate 6 steps
typescript 
import { Pipe, PipeTransform, Inject, LOCALE_ID } from '@angular/core';
 
interface MoneyOptions {
  currency?: string;

Building a cached money pipe in Angular

pipes memoization internationalization
Intermediate 8 steps
java 
@AutoConfiguration
@EnableConfigurationProperties(RateLimiterProperties.class)
@ConditionalOnClass(RateLimiter.class)
public class RateLimiterAutoConfiguration {

Building a Spring Boot rate-limiter auto-config

auto-configuration conditional-beans rate-limiting
Intermediate 7 steps
php 
final class Container
{
    private array $bindings = [];
    private array $instances = [];

Building a DI container with reflection in PHP

dependency-injection reflection autowiring
Advanced 9 steps
php 
<?php
 
namespace App\Services;
 

Caching per-tenant settings in Laravel

caching multi-tenancy dependency-injection
Intermediate 7 steps
go 
package admin
 
import (
	"net/http"

Building a protected admin area in Gin

routing middleware authentication
Intermediate 6 steps
typescript 
import { Injectable, signal, computed } from '@angular/core';
 
export type ToastKind = 'success' | 'error' | 'info' | 'warning';
 

Building a signal-based toast service in Angular

signals state-management dependency-injection
Intermediate 8 steps
typescript 
import { Injectable, NotFoundException, ConflictException } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository, DeepPartial } from 'typeorm';
import { User } from './entities/user.entity';

Building a CRUD service in NestJS

crud dependency-injection repository-pattern
Intermediate 7 steps
go 
package handlers
 
import (
	"context"

Liveness vs readiness health checks in Gin

health-checks dependency-injection context-timeout
Intermediate 7 steps
typescript 
import { Controller, Get, Param, Query, Redirect, NotFoundException } from '@nestjs/common';
import { LinksService } from './links.service';
 
@Controller('links')

Handling HTTP redirects in NestJS

redirects routing decorators
Intermediate 7 steps
python 
import secrets
from datetime import datetime, timedelta, timezone
 
from fastapi import APIRouter, Cookie, Depends, HTTPException, Response, status

Cookie session auth in FastAPI

session-authentication cookies dependency-injection
Intermediate 8 steps
python 
from fastapi import APIRouter, Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from jose import JWTError, jwt
from sqlalchemy.orm import Session

Chaining auth dependencies in FastAPI

dependency-injection jwt-authentication authorization
Intermediate 8 steps