169 lines
4.7 KiB
Markdown
169 lines
4.7 KiB
Markdown
#Pagination and rows number
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Following methods allow you to paginate and limit number of rows in queries.
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* `paginate(page: int) -> QuerySet`
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* `limit(limit_count: int) -> QuerySet`
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* `offset(offset: int) -> QuerySet`
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* `get() -> Model`
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* `first() -> Model`
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* `QuerysetProxy`
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* `QuerysetProxy.paginate(page: int)` method
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* `QuerysetProxy.limit(limit_count: int)` method
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* `QuerysetProxy.offset(offset: int)` method
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## paginate
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`paginate(page: int, page_size: int = 20) -> QuerySet`
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Combines the `offset` and `limit` methods based on page number and size
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```python
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class Track(ormar.Model):
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class Meta:
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tablename = "track"
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metadata = metadata
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database = database
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id: int = ormar.Integer(primary_key=True)
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album: Optional[Album] = ormar.ForeignKey(Album)
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name: str = ormar.String(max_length=100)
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position: int = ormar.Integer()
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```
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```python
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tracks = await Track.objects.paginate(3).all()
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# will return 20 tracks starting at row 41
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# (with default page size of 20)
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```
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Note that `paginate(2)` is equivalent to `offset(20).limit(20)`
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## limit
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`limit(limit_count: int, limit_raw_sql: bool = None) -> QuerySet`
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You can limit the results to desired number of parent models.
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To limit the actual number of database query rows instead of number of main models
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use the `limit_raw_sql` parameter flag, and set it to `True`.
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```python
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class Track(ormar.Model):
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class Meta:
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tablename = "track"
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metadata = metadata
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database = database
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id: int = ormar.Integer(primary_key=True)
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album: Optional[Album] = ormar.ForeignKey(Album)
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name: str = ormar.String(max_length=100)
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position: int = ormar.Integer()
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```
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```python
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tracks = await Track.objects.limit(1).all()
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# will return just one Track
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```
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!!!note
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All methods that do not return the rows explicitly returns a QueySet instance so you can chain them together
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So operations like `filter()`, `select_related()`, `limit()` and `offset()` etc. can be chained.
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Something like `Track.object.select_related("album").filter(album__name="Malibu").offset(1).limit(1).all()`
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## offset
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`offset(offset: int, limit_raw_sql: bool = None) -> QuerySet`
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You can also offset the results by desired number of main models.
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To offset the actual number of database query rows instead of number of main models
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use the `limit_raw_sql` parameter flag, and set it to `True`.
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```python
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class Track(ormar.Model):
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class Meta:
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tablename = "track"
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metadata = metadata
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database = database
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id: int = ormar.Integer(primary_key=True)
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album: Optional[Album] = ormar.ForeignKey(Album)
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name: str = ormar.String(max_length=100)
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position: int = ormar.Integer()
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```
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```python
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tracks = await Track.objects.offset(1).limit(1).all()
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# will return just one Track, but this time the second one
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```
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!!!note
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All methods that do not return the rows explicitly returns a QueySet instance so you can chain them together
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So operations like `filter()`, `select_related()`, `limit()` and `offset()` etc. can be chained.
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Something like `Track.object.select_related("album").filter(album__name="Malibu").offset(1).limit(1).all()`
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## get
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`get(**kwargs) -> Model`
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Get's the first row from the db meeting the criteria set by kwargs.
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If no criteria is set it will return the last row in db sorted by pk.
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(The criteria cannot be set also with filter/exclude).
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!!!tip
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To read more about `get` visit [read/get](./read/#get)
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## first
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`first() -> Model`
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Gets the first row from the db ordered by primary key column ascending.
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!!!tip
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To read more about `first` visit [read/first](./read/#first)
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## QuerysetProxy methods
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When access directly the related `ManyToMany` field as well as `ReverseForeignKey`
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returns the list of related models.
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But at the same time it exposes subset of QuerySet API, so you can filter, create,
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select related etc related models directly from parent model.
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### paginate
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Works exactly the same as [paginate](./#paginate) function above but allows you to paginate related
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objects from other side of the relation.
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!!!tip
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To read more about `QuerysetProxy` visit [querysetproxy][querysetproxy] section
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### limit
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Works exactly the same as [limit](./#limit) function above but allows you to paginate related
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objects from other side of the relation.
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!!!tip
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To read more about `QuerysetProxy` visit [querysetproxy][querysetproxy] section
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### offset
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Works exactly the same as [offset](./#offset) function above but allows you to paginate related
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objects from other side of the relation.
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!!!tip
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To read more about `QuerysetProxy` visit [querysetproxy][querysetproxy] section
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[querysetproxy]: ../relations/queryset-proxy.md |