Bulk update django

Flimm k 35 35 gold badges silver badges bronze badges. But ModelClass. Shashank have you found any solution for your case yet? I am also having the same scenario. F objects cannot be used to reference different models in the. Docs have a small mention of this. If you want to pull data from another model to update your entries, you'll have to run a for loop — sean.

I tried django-bulk-update, and I personally discourage using it. MarcGarcia good point. I found many developers use external libraries without knowing their impact — Dejell. MarcGarcia I disagree that bulk update is not valuable and only really needed when thousands of updates are necessary. Using it to do 10, rows at once is not advisable for the reasons you mentioned, but using it to update 50 rows at once is much more efficient than hitting the db with 50 separate update requests.

The best solutions I found are: a use transaction. Show 4 more comments. Tim Tisdall 8, 3 3 gold badges 44 44 silver badges 71 71 bronze badges. Indeed, it is listed in the release notes for 2. IT returns number of objects are updated in table. Thanks in advance : Thank you for keep an attention ;. You may also want to use an external project like django-debug-toolbar , or a tool that monitors your database directly.

Remember that you may be optimizing for speed or memory or both, depending on your requirements. Sometimes optimizing for one will be detrimental to the other, but sometimes they will help each other. Also, work that is done by the database process might not have the same cost to you as the same amount of work done in your Python process. It is up to you to decide what your priorities are, where the balance must lie, and profile all of these as required since this will depend on your application and server.

With everything that follows, remember to profile after every change to ensure that the change is a benefit, and a big enough benefit given the decrease in readability of your code. All of the suggestions below come with the caveat that in your circumstances the general principle might not apply, or might even be reversed. We will assume you have done the things listed above.

The rest of this document focuses on how to use Django in such a way that you are not doing unnecessary work. This document also does not address other optimization techniques that apply to all expensive operations, such as general purpose caching.

Understanding QuerySets is vital to getting good performance with simple code. In particular:. As well as caching of the whole QuerySet , there is caching of the result of attributes on ORM objects. In general, attributes that are not callable will be cached. For example, assuming the example blog models :. Be careful when reading template code - the template system does not allow use of parentheses, but will call callables automatically, hiding the above distinction.

It is an optional argument. By default, all the objects are updated and saved. In models. Every model has a save method. This is a database setting, not a Django setting. For more information about this, see the collation section in the databases documentation.

Case-insensitive exact match. Note this will match the headline 'Lennon honored today' but not 'lennon honored today'. See the database note for more information. In a given iterable; often a list, tuple, or queryset. You can also use a queryset to dynamically evaluate the list of values instead of providing a list of literal values:.

For example, this will work filtering on the blog names :. This example will raise an exception, since the inner query is trying to extract two field values, where only one is expected:.

It is more efficient, in those cases, to extract a list of values and then pass that into the second query. That is, execute two queries instead of one:. Note the list call around the Blog QuerySet to force execution of the first query.

Without it, a nested query would be executed, because QuerySets are lazy. Refer to the database note documentation for more. For datetime fields, casts the value as date. Allows chaining additional field lookups. Takes a date value. No equivalent SQL code fragment is included for this lookup because implementation of the relevant query varies among different database engines.

This requires time zone definitions in the database. For date and datetime fields, an exact year match. Takes an integer year. For date and datetime fields, an exact ISO week-numbering year match. For date and datetime fields, an exact month match. Takes an integer 1 January through 12 December. For date and datetime fields, an exact day match. Takes an integer day.

For date and datetime fields, return the week number or 53 according to ISO , i. Week days are indexed with day 1 being Sunday and day 7 being Saturday. For date and datetime fields, an exact ISO day of the week match. Week days are indexed with day 1 being Monday and day 7 being Sunday. Takes an integer value between 1 and 4 representing the quarter of the year. For datetime fields, casts the value as time.

Takes a datetime. For datetime and time fields, an exact hour match. Takes an integer between 0 and For datetime and time fields, an exact minute match.

For datetime and time fields, an exact second match. The regular expression syntax is that of the database backend in use. Using raw strings e. Django provides the following aggregation functions in the django. For details on how to use these aggregate functions, see the topic guide on aggregation. See the Aggregate documentation to learn how to create your aggregates.

Aggregation functions return None when used with an empty QuerySet. For example, the Sum aggregation function returns None instead of 0 if the QuerySet contains no entries.

To return another value instead, pass a value to the default argument. An exception is Count , which does return 0 if the QuerySet is empty. Count does not support the default argument. Strings that reference fields on the model, transforms of the field, or query expressions. An optional argument that represents the model field of the return value.

See Conditional aggregation and Filtering on annotations for example usage. An optional argument that allows specifying a value to use as a default value when the queryset or grouping contains no entries. The default value is False. The default argument is not supported. By default, StdDev returns the population standard deviation. By default, Variance returns the population variance. A Q object represents an SQL condition that can be used in database-related operations.

See Complex lookups with Q objects. The queryset argument supplies a base QuerySet for the given lookup. Prefetches the given lookups on an iterable of model instances. This is useful in code that receives a list of model instances as opposed to a QuerySet ; for example, when fetching models from a cache or instantiating them manually. Pass an iterable of model instances must all be of the same class and the lookups or Prefetch objects you want to prefetch for.

This can be overridden by using a custom queryset in a related lookup. A Q object to control the filtering. For example, to find restaurants that have vegetarian pizzas with 'mozzarella' in the name:.

Offline Django 4. Django is a registered trademark of the Django Software Foundation. Django The web framework for perfectionists with deadlines.

Documentation Search: Search. Getting Help el es fr id it ja ko pl pt-br zh-hans Language: en 1. You can evaluate a QuerySet in the following ways: Iteration. For example, this will print the headline of all entries in the database: for e in Entry.

Note The query parameter to QuerySet exists so that specialized query subclasses can reconstruct internal query state. Example: Entry. Note It is permissible to specify a multi-valued field to order the results by for example, a ManyToManyField field, or the reverse relation of a ForeignKey field. DateField Event. Warning Ordering is not a free operation. For example, if the Blog model defined an ordering by name : Entry.

This example compares the dictionaries of values with the normal model objects: This list contains a Blog object.

Warning Because ManyToManyField attributes and reverse relations can have multiple related rows, including these can have a multiplier effect on the size of your result set.

All dates will be a Monday. Note This function performs time zone conversions directly in the database. This translates into the following requirements: SQLite: no requirements. Conversions are performed in Python. Oracle: no requirements see Choosing a Time Zone File. Hits the database. Model Hits the database with joins to the author and hometown tables. For example, suppose you have these models: from django.

Note Remember that, as always with QuerySets , any subsequent chained methods which imply a different database query will ignore previously cached results, and retrieve data using a fresh database query. Note The ordering of lookups matters. Use this method as a last resort This is an old API that we aim to deprecate at some point in the future.

Warning You should be very careful whenever you use extra. This is done by passing the names of the fields to not load to defer : Entry. Defers both the body and headline fields. Load all fields immediately. Note The defer method and its cousin, only , below are only for advanced use-cases. For example, both of these models use the same underlying database table: class CommonlyUsedModel models.

Note When calling save for instances with deferred fields, only the loaded fields will be saved. The following two querysets are the same, in terms of deferred fields: Person. This will defer all fields except the headline. Final result is that everything except "headline" is deferred. For example: queries the database with the 'default' alias. For example: from django.

For example: Restaurant. Changed in Django 3. Changed in Django 4. The following are equivalent: Model. For example: Entry. Being the following models: class Chapter models. ManyToManyField Chapter. This is meant as a shortcut to boilerplatish code. Example: Returns the total number of entries in the database.

The Oracle database driver always uses server-side cursors. You may want to filter out null values: Entry. Entry': 2, 'blog. Blog': 1, 'blog. Examples: Entry. Example: Blog.