Django Rest Framework serializer tips

Django Rest Framework serializer tips.ipynb

{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "from django.conf import settings\n",
    "settings.configure(DEBUG=True)\n",
    "import django\n",
    "django.setup()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "from rest_framework import serializers"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Use case 0: Using serializers to validate data"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "class BookSerializer(serializers.Serializer):\n",
    "    title = serializers.CharField(max_length=60, required=True)\n",
    "    author = serializers.CharField(max_length=60, required=True)\n",
    "    tags = serializers.ListField(\n",
    "        child=serializers.CharField(),\n",
    "        max_length=3,\n",
    "        required=False)\n",
    "    date_added = serializers.DateField()\n",
    "    is_cool = serializers.BooleanField(default=False)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [],
   "source": [
    "input_data = {\n",
    "    'title': 'Chram na Lednicy',\n",
    "    'author': 'Andrzej Nowakowski',\n",
    "    'tags': ['fantasy', 'legend'],\n",
    "    'date_added': '2018-04-01',\n",
    "    'is_cool': True,\n",
    "}"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [],
   "source": [
    "serializer = BookSerializer(data=input_data)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "serializer.is_valid()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "`data` is the input being serialized while `validated_data` is the output. Observe type conversion for the `DateField`."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{'title': 'Chram na Lednicy', 'author': 'Andrzej Nowakowski', 'tags': ['fantasy', 'legend'], 'date_added': '2018-04-01', 'is_cool': True}"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "serializer.data"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "OrderedDict([('title', 'Chram na Lednicy'),\n",
       "             ('author', 'Andrzej Nowakowski'),\n",
       "             ('tags', ['fantasy', 'legend']),\n",
       "             ('date_added', datetime.date(2018, 4, 1)),\n",
       "             ('is_cool', True)])"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "serializer.validated_data"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Now let's try with incorrect data:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [],
   "source": [
    "bad_data = {\n",
    "    'author': \"Very long name \" * 10,\n",
    "    'tags': 123,\n",
    "    'date_added': 'Wednesday',\n",
    "    'is_cool': 1,\n",
    "}"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [],
   "source": [
    "bad_serializer = BookSerializer(data=bad_data)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "bad_serializer.is_valid()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{'author': 'Very long name Very long name Very long name Very long name Very long name Very long name Very long name Very long name Very long name Very long name ', 'tags': 123, 'date_added': 'Wednesday', 'is_cool': 1}"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "bad_serializer.data"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{}"
      ]
     },
     "execution_count": 13,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "bad_serializer.validated_data"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{'title': [ErrorDetail(string='This field is required.', code='required')],\n",
       " 'author': [ErrorDetail(string='Ensure this field has no more than 60 characters.', code='max_length')],\n",
       " 'tags': [ErrorDetail(string='Expected a list of items but got type \"int\".', code='not_a_list')],\n",
       " 'date_added': [ErrorDetail(string='Date has wrong format. Use one of these formats instead: YYYY[-MM[-DD]].', code='invalid')]}"
      ]
     },
     "execution_count": 14,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "dict(bad_serializer.errors)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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