{"id":6427,"date":"2023-01-13T03:44:48","date_gmt":"2023-01-13T03:44:48","guid":{"rendered":"https:\/\/www.pythontutorial.net\/?page_id=6427"},"modified":"2023-08-30T02:01:24","modified_gmt":"2023-08-30T02:01:24","slug":"django-limit-offset","status":"publish","type":"page","link":"https:\/\/www.pythontutorial.net\/django-tutorial\/django-limit-offset\/","title":{"rendered":"Django Limit Offset"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn how to limit a QuerySet<\/code> in Django, which is equivalent to the SQL’s LIMIT<\/code> and OFFSET<\/code> clauses.<\/p>\n\n\n\n

In practice, you rarely get all the rows from one or more tables in the database. Instead, you get a subset of rows for displaying on a web page.<\/p>\n\n\n\n

Django uses the slicing<\/a> syntax to limit a QuerySet<\/code> to a specific number of objects. Behind the scenes, Django executes a SQL SELECT<\/code> statement with LIMIT<\/code> and OFFSET<\/code> clauses.<\/p>\n\n\n\n

Suppose you want to access the first 10 rows in a table, you can use the following slicing:<\/p>\n\n\n

Entity.objects.all()[:10<\/span>]<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Since the table stores the rows in an unspecified order, the “first 10 objects” become unpredictable.<\/p>\n\n\n\n
Entity.objects.all().order_by(field_name)[:10<\/span>]<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
To get the rows from 10 to 20, you can use the following slicing:<\/p>\n\n\n
Entity.objects.all().order_by(field_name)[10<\/span>:20<\/span>]<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
In general, the syntax for limiting results is as follows:<\/p>\n\n\n
Entity.objects.all()[Offset:Offset+Limit]<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
In this syntax, the Offset<\/code> is the number of rows you want to skip and the Limit<\/code> is the number of rows you want to retrieve.<\/p>\n\n\n\n
Note that Django doesn’t support negative indexing like:<\/p>\n\n\n
Entity.objects.all().order_by(field_name)[-10<\/span>]<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Also, when you slice a QuerySet<\/code><\/code>, Django returns a new QuerySet<\/code><\/code>.<\/p>\n\n\n\n
To retrieve the first or last row, you should use the first()<\/code> or last()<\/code> method because if the QuerySet<\/code> is empty and you use a slice:<\/p>\n\n\n
Entity.objects.all().order_by(field_name)[0<\/span>]<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
…then you’ll get an IndexError<\/code> exception.<\/p>\n\n\n\n
Django Limit Offset example #<\/a><\/h2>\n\n\n\n
We’ll use the Employee<\/code> model from the HR<\/code> app for the demonstration. The Employee<\/code> model maps to the hr_employee<\/code> table:<\/p>\n\n\n\n
\"\"<\/figure>\n\n\n\n
The following example gets the first 10 employees ordered by their first names:<\/p>\n\n\n
>>> <\/span>Employee.objects.all().order_by('first_name'<\/span>)[:10<\/span>] \nSELECT \"hr_employee\"<\/span>.\"id\"<\/span>,\n       \"hr_employee\"<\/span>.\"first_name\"<\/span>,\n       \"hr_employee\"<\/span>.\"last_name\"<\/span>,\n       \"hr_employee\"<\/span>.\"contact_id\"<\/span>,\n       \"hr_employee\"<\/span>.\"department_id\"<\/span>\n  FROM \"hr_employee\"<\/span>\n ORDER BY \"hr_employee\"<\/span>.\"first_name\"<\/span> ASC\n LIMIT 10<\/span>\nExecution time: 0.000000<\/span>s [Database: default]\n<QuerySet [<Employee: Aaron Pearson>, <Employee: Adam Crane>, <Employee: Adam Stewart>, <Employee: Adrienne Green>, <Employee: Alan Johnson>, <Employee: Alexa West>, <Employee: Alicia Wyatt>, <Employee: Amanda Benson>, <Employee: Amber Brown>, <Employee: Amy Lopez>]><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The following example skips the first 10 rows and gets the next 10 rows from the hr_employee<\/code> table:<\/p>\n\n\n
>>> <\/span>Employee.objects.order_by('first_name'<\/span>)[10<\/span>:20<\/span>] \nSELECT \"hr_employee\"<\/span>.\"id\"<\/span>,\n       \"hr_employee\"<\/span>.\"first_name\"<\/span>,\n       \"hr_employee\"<\/span>.\"last_name\"<\/span>,\n       \"hr_employee\"<\/span>.\"contact_id\"<\/span>,\n       \"hr_employee\"<\/span>.\"department_id\"<\/span>\n  FROM \"hr_employee\"<\/span>\n ORDER BY \"hr_employee\"<\/span>.\"first_name\"<\/span> ASC\n LIMIT 10<\/span>\nOFFSET 10<\/span>\nExecution time: 0.001001<\/span>s [Database: default]\n<QuerySet [<Employee: Amy Lee>, <Employee: Andre Perez>, <Employee: Andrea Mcintosh>, <Employee: Andrew Dixon>, <Employee: Andrew Guerra>, <Employee: Ann Chang>, \n<Employee: Anne Odom>, <Employee: Anthony Fuentes>, <Employee: Anthony Welch>, <Employee: Ashley Brown>]><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Summary #<\/a><\/h2>\n\n\n\n
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  • Django uses array-slicing syntax to limit the number of objects returned by a QuerySet<\/code>.<\/li>\n<\/ul>\n
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Therefore, you should always sort the results<\/a> before slicing the query. For example, the following gets the first 10 rows ordered by the field_name<\/code>:<\/p>\n\n\n