{"id":910,"date":"2022-02-09T00:37:42","date_gmt":"2022-02-09T00:37:42","guid":{"rendered":"https:\/\/zerotobyte.com\/?p=910"},"modified":"2022-02-09T00:44:16","modified_gmt":"2022-02-09T00:44:16","slug":"django-arrayfield-working-with-arrays","status":"publish","type":"post","link":"https:\/\/zerotobyte.com\/django-arrayfield-working-with-arrays\/","title":{"rendered":"Django ArrayField &#8211; Working with Arrays"},"content":{"rendered":"\n<p>Since the introduction of Django 1.8, we were introduced with new Fields specific to the PostgreSQL database &#8211; <strong>ArrayField, CIText fields, HStoreField and Range Fields<\/strong>. In this article, we&#8217;ll focus on <code>ArrayField<\/code>.<\/p>\n\n\n\n<p>What is ArrayField in Django?<\/p>\n\n\n\n<p><strong>ArrayField is Field that represents a column in the PostgreSQL database. It&#8217;s used to store data arrays in one model instance without needing an OneToMany relationship. ArrayField can represent any Field type except ForeignKey, OneToOneField, and ManyToManyField.<\/strong><\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"django-arrayfield-arguments\">Django ArrayField arguments<\/h2>\n\n\n\n<p>ArrayField in Django consists of one required argument &#8211; base_field and one optional argument &#8211; size, also all other Field options are available.<\/p>\n\n\n\n<p><strong><code>ArrayField(base_field, size=None, **options)<\/code><\/strong><\/p>\n\n\n\n<ul><li><strong><code>base_field<\/code><\/strong> &#8211; Subclass of Field class.<\/li><li><strong><code>size<\/code><\/strong> &#8211; Maximum size of the array.<\/li><li><strong><code>**options<\/code><\/strong> &#8211; Default Field options explained in <a href=\"https:\/\/docs.djangoproject.com\/en\/4.0\/ref\/models\/fields\/#field-options\" target=\"_blank\" rel=\"noreferrer noopener\">official Django documentation.<\/a><\/li><\/ul>\n\n\n\n<pre class=\"wp-block-verse\"><strong>WARNING<\/strong> - PostgreSQL doesn't raise an exception or warning if our array length is greater even if we specify the size argument.<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"django-arrayfield-in-models\">Django ArrayField in Models<\/h2>\n\n\n\n<p>Previously we&#8217;ve seen arguments and acknowledged what they do. Now, let&#8217;s create the model and see how migrations affect our PostgreSQL database.<\/p>\n\n\n\n<p>Our model represents the Author. It has autogenerated id, name, and books columns.<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"python\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">from django.contrib.postgres.fields import ArrayField\nfrom django.db import models\n\nclass Author(models.Model):\n   name = models.CharField(max_length=512)\n   books = ArrayField(\n       models.CharField(max_length=512)\n   )<\/pre>\n\n\n\n<p>Using Django ORM (Object-Relational Mapper), we can create instances of the Author model.<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">>>> Author.objects.create(name=\"William Shakespeare\", books=[\"Hamlet\", \"Romeo and Juliet\", \"Macbeth\"])\n\n&lt;Author: Author object (1)>\n\n>>> Author.objects.create(name=\"Miguel de Cervantes\", books=[\"Don Quixote\", \"Novelas Ejemplares\"])\n\n&lt;Author: Author object (2)><\/pre>\n\n\n\n<p>Let&#8217;s take a quick look at the PostgreSQL database. The following table shows columns and data created in the previous example.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><tbody><tr><td><strong>id<\/strong><\/td><td><strong>name<\/strong><\/td><td><strong>books<\/strong><\/td><\/tr><tr><td>1<\/td><td>William Shakespeare<\/td><td>{\u201cHamlet\u201d,&#8221;Romeo and Juliet&#8221;,\u201dMacbeth\u201d}<\/td><\/tr><tr><td>2<\/td><td>Miguel de Cervantes<\/td><td>{&#8220;Don Quixote&#8221;,&#8221;Novelas Ejemplares&#8221;}<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>As You can see, the books column doesn&#8217;t really contain an array if we take [ ] as &#8220;python array&#8221; syntax.<\/p>\n\n\n\n<pre class=\"wp-block-verse\"><strong>NOTE<\/strong> - Arrays can be multidimensional; every dimension is divided by { }<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"arrayfield-orm-queries\">ArrayField ORM queries<\/h2>\n\n\n\n<p>ORM provides us to write queries in a more &#8220;python way&#8221; instead of writing SQL queries. ORM might often be a bit abstract, but once you master it can become a tool, you can&#8217;t stop using.<\/p>\n\n\n\n<p>Having that in mind, to use ArrayField, it&#8217;s helpful to know some basic Django ORM queries we can use.<\/p>\n\n\n\n<p>Just for the sake of example, I&#8217;ll use queries on the following data in the database:<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><tbody><tr><td><strong>id<\/strong><\/td><td><strong>name<\/strong><\/td><td><strong>books<\/strong><\/td><\/tr><tr><td>1<\/td><td>William Shakespeare<\/td><td>{\u201cHamlet\u201d,&#8221;Romeo and Juliet&#8221;,\u201dMacbeth\u201d}<\/td><\/tr><tr><td>2<\/td><td>Miguel de Cervantes<\/td><td>{&#8220;Don Quixote&#8221;,&#8221;Novelas Ejemplares&#8221;}<\/td><\/tr><tr><td>3<\/td><td>Unknown Author<\/td><td>{\u201cHamlet\u201d,\u201dMacbeth\u201d,&#8221;Don Quixote&#8221;}<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># Filters Authors based on books they contain\n>>> Author.objects.filter(books__contains=[\"Hamlet\"])\n&lt;QuerySet [&lt;Author: Author object (1)>, &lt;Author: Author object (3)>]>\n\n# Filters Authors Based on subset\n>>> Author.objects.filter(books__contained_by=[\"Hamlet\", \"Macbeth\", \"Don Quixote\"])\n&lt;QuerySet [&lt;Author: Author object (3)>]>\n\n# Filters Authors which books overlap with given array\n>>> Author.objects.filter(books__overlap=[\"Hamlet\", \"Macbeth\"])\n&lt;QuerySet [&lt;Author: Author object (1)>, &lt;Author: Author object (3)>]>\n\n# Filters Authors that have array of given length\n>>> Author.objects.filter(books__len=3)\n&lt;QuerySet [&lt;Author: Author object (1)>, &lt;Author: Author object (3)>]>\n<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"arrayfield-or-onetomanyfield\">ArrayField or OneToManyField<\/h2>\n\n\n\n<p>Since ArrayField might represent data connected to the given model, one might consider using OneToManyField instead of ArrayField. So which one to choose?<\/p>\n\n\n\n<p>ArrayField in Django should be used only if it represents some kind of instance information that doesn&#8217;t often change or become too massive to handle. <strong>Of course, some specific use cases might find ArrayField helpful, but use OneToMany and ManyToMany connections for everything else. Querying is more manageable, and it&#8217;s the standard way of doing it in practice.<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-verse\"><strong>NOTE<\/strong> - Instead of using ArrayField, consider if <a href=\"https:\/\/django-taggit.readthedocs.io\/en\/latest\/getting_started.html\" target=\"_blank\" rel=\"noreferrer noopener\">django-taggit library<\/a> would be a better solution for your use case.<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Since the introduction of Django 1.8, we were introduced with new Fields specific to the PostgreSQL database &#8211; ArrayField, CIText &#8230; <\/p>\n<p class=\"read-more-container\"><a title=\"Django ArrayField &#8211; Working with Arrays\" class=\"read-more button\" href=\"https:\/\/zerotobyte.com\/django-arrayfield-working-with-arrays\/#more-910\" aria-label=\"More on Django ArrayField &#8211; Working with Arrays\">Read more<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[8],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v20.4 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Django ArrayField - Working with Arrays - ZeroToByte<\/title>\n<meta name=\"description\" content=\"Learn good practices of creating your models and the difference between Django ArrayField and OneToMany relationships.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/zerotobyte.com\/django-arrayfield-working-with-arrays\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Django ArrayField - Working with Arrays - ZeroToByte\" \/>\n<meta property=\"og:description\" content=\"Learn good practices of creating your models and the difference between Django ArrayField and OneToMany relationships.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/zerotobyte.com\/django-arrayfield-working-with-arrays\/\" \/>\n<meta property=\"og:site_name\" content=\"ZeroToByte\" \/>\n<meta property=\"article:published_time\" content=\"2022-02-09T00:37:42+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2022-02-09T00:44:16+00:00\" \/>\n<meta name=\"author\" content=\"Manuel Matosevic\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Manuel Matosevic\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"3 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/zerotobyte.com\/django-arrayfield-working-with-arrays\/\",\"url\":\"https:\/\/zerotobyte.com\/django-arrayfield-working-with-arrays\/\",\"name\":\"Django ArrayField - Working with Arrays - ZeroToByte\",\"isPartOf\":{\"@id\":\"https:\/\/zerotobyte.com\/#website\"},\"datePublished\":\"2022-02-09T00:37:42+00:00\",\"dateModified\":\"2022-02-09T00:44:16+00:00\",\"author\":{\"@id\":\"https:\/\/zerotobyte.com\/#\/schema\/person\/1ff5aa0c2aabf4491b171a0aee7874a3\"},\"description\":\"Learn good practices of creating your models and the difference between Django ArrayField and OneToMany relationships.\",\"breadcrumb\":{\"@id\":\"https:\/\/zerotobyte.com\/django-arrayfield-working-with-arrays\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/zerotobyte.com\/django-arrayfield-working-with-arrays\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/zerotobyte.com\/django-arrayfield-working-with-arrays\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/zerotobyte.com\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Django ArrayField &#8211; 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