Code Explainers

Code explainers tagged #orm

python 
from django.db import models
from django.db.models import F, Sum, DecimalField
from django.db.models.functions import Coalesce
 

Recomputing order totals in Django

annotations aggregation custom-manager
Intermediate 9 steps
python 
from datetime import datetime, timezone
 
from flask import abort
from sqlalchemy import Column, DateTime

Soft deletes with a custom SQLAlchemy Query in Flask

soft-delete mixin query-subclass
Advanced 7 steps
python 
from flask import Flask, g, current_app
from sqlalchemy import create_engine
from sqlalchemy.orm import scoped_session, sessionmaker
 

Scoped SQLAlchemy sessions in Flask

database session-management connection-pooling
Intermediate 6 steps
python 
from datetime import datetime
 
from flask import Blueprint, abort, redirect, request
from sqlalchemy import func

Building a URL shortener redirect in Flask

routing url-shortener orm
Intermediate 6 steps
python 
from typing import Optional
 
from fastapi import APIRouter, Depends, HTTPException, status
from pydantic import BaseModel, EmailStr, Field

How PATCH partial updates work in FastAPI

partial-update validation dependency-injection
Intermediate 8 steps
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
python 
from django.db.models import Q
 
from .models import Order
 

DISTINCT ON queries in Django

orm querysets postgresql
Intermediate 7 steps
python 
from flask import Blueprint, request, jsonify
from marshmallow import Schema, fields, validate, ValidationError, EXCLUDE
 
from .models import db, User

How a Flask blueprint validates and creates users

validation rest-api schema
Intermediate 8 steps
python 
import random
 
import click
from faker import Faker

Building a Flask seed command with Click

cli database seeding orm
Intermediate 7 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
typescript 
import { Module } from '@nestjs/common';
import { TypeOrmModule } from '@nestjs/typeorm';
import { BullModule } from '@nestjs/bullmq';
 

How a NestJS feature module wires up

dependency-injection modularity orm
Intermediate 7 steps
go 
package handlers
 
import (
	"net/http"

Query-string filtering in Gin with GORM

query-binding validation conditional-queries
Intermediate 8 steps
python 
from fastapi import APIRouter, Depends, Response, status
from sqlalchemy.orm import Session
 
from .database import get_db

Building a REST article resource in FastAPI

dependency injection rest api orm
Intermediate 8 steps
java 
@Repository
public interface OrderRepository extends JpaRepository<Order, Long> {
 
    @EntityGraph(attributePaths = {"customer", "lineItems", "lineItems.product"})

Killing N+1 queries with @EntityGraph in Spring

orm fetching n+1-problem
Intermediate 5 steps
java 
package com.example.shop.repository;
 
import com.example.shop.domain.Order;
import com.example.shop.domain.OrderStatus;

Deriving JPA queries from method names in Spring

query derivation repositories pagination
Intermediate 8 steps
python 
from datetime import datetime, date
from decimal import Decimal
from flask import Flask, jsonify
from flask.json.provider import DefaultJSONProvider

Serializing SQLAlchemy models in Flask JSON

serialization orm json
Intermediate 6 steps
python 
from datetime import datetime
from fastapi import APIRouter, Depends, HTTPException, status
from pydantic import BaseModel, ConfigDict, EmailStr
from sqlalchemy.orm import Session

Building a users router in FastAPI

routing serialization dependency-injection
Intermediate 7 steps
python 
from dataclasses import dataclass
from typing import Optional
 
from sqlalchemy import select, func

Building a pagination helper with SQLAlchemy

pagination dataclass computed-properties
Intermediate 8 steps