bump version, update docs

2020-12-01 10:41:07 +01:00
parent 4c4e6248b0
commit 3ac767ed0f
13 changed files with 364 additions and 81 deletions
--- a/docs/relations.md
+++ b/docs/relations.md
@ -29,6 +29,83 @@ By default it's child (source) `Model` name + s, like courses in snippet below:
 --8<-- "../docs_src/fields/docs001.py"
 ```

+Reverse relation exposes API to manage related objects also from parent side.
+
+##### add
+
+Adding child model from parent side causes adding related model to currently loaded parent relation, 
+as well as sets child's model foreign key value and updates the model.
+
+```python
+department = await Department(name="Science").save()
+course = Course(name="Math", completed=False) # note - not saved
+
+await department.courses.add(course)
+assert course.pk is not None # child model was saved
+# relation on child model is set and FK column saved in db
+assert courses.department == department
+# relation on parent model is also set
+assert department.courses[0] == course 
+```
+
+!!!warning
+    If you want to add child model on related model the primary key value for parent model **has to exist in database**.
+    
+    Otherwise ormar will raise RelationshipInstanceError as it cannot set child's ForeignKey column value 
+    if parent model has no primary key value.
+    
+    That means that in example above the department has to be saved before you can call `department.courses.add()`.
+
+##### remove
+
+Removal of the related model one by one.
+
+In reverse relation calling `remove()` does not remove the child model, but instead nulls it ForeignKey value.
+
+```python
+# continuing from above
+await department.courses.remove(course)
+assert len(department.courses) == 0
+# course still exists and was saved in remove
+assert course.pk is not None
+assert course.department is None
+
+# to remove child from db
+await course.delete()
+```
+
+But if you want to clear the relation and delete the child at the same time you can issue:
+
+```python
+# this will not only clear the relation 
+# but also delete related course from db
+await department.courses.remove(course, keep_reversed=False)
+```
+
+##### clear
+
+Removal of all related models in one call.
+
+Like remove by default `clear()` nulls the ForeigKey column on child model (all, not matter if they are loaded or not).
+
+```python
+# nulls department column on all courses related to this department
+await department.courses.clear()
+```
+
+If you want to remove the children altogether from the database, set `keep_reversed=False`
+
+```python
+# deletes from db all courses related to this department 
+await department.courses.clear(keep_reversed=False)
+```
+
+##### QuerysetProxy
+
+Reverse relation exposes QuerysetProxy API that allows you to query related model like you would issue a normal Query.
+
+To read which methods of QuerySet are available read below [querysetproxy][querysetproxy]
+
 #### related_name

 But you can overwrite this name by providing `related_name` parameter like below:
@ -94,7 +171,7 @@ Sqlalchemy column and Type are automatically taken from target `Model`.
 * Sqlalchemy column: class of a target `Model` primary key column  
 * Type (used for pydantic): type of a target `Model` 

-####Defining `Models`:
+####Defining `Models`

 ```Python
 --8<-- "../docs_src/relations/docs002.py"
@ -107,7 +184,7 @@ post = await Post.objects.create(title="Hello, M2M", author=guido)
 news = await Category.objects.create(name="News")
 ```

-#### Adding related models
+#### add

 ```python
 # Add a category to a post.
@ -121,7 +198,110 @@ await news.posts.add(post)
    
    Otherwise an IntegrityError will be raised by your database driver library.

-#### create()
+#### remove
+
+Removal of the related model one by one.
+
+Removes also the relation in the database.
+
+```python
+await news.posts.remove(post)
+```
+
+#### clear
+
+Removal of all related models in one call.
+
+Removes also the relation in the database.
+
+```python
+await news.posts.clear()
+```
+
+#### QuerysetProxy
+
+Reverse relation exposes QuerysetProxy API that allows you to query related model like you would issue a normal Query.
+
+To read which methods of QuerySet are available read below [querysetproxy][querysetproxy]
+
+### QuerySetProxy
+
+When access directly the related `ManyToMany` field as well as `ReverseForeignKey` returns the list of related models.
+
+But at the same time it exposes subset of QuerySet API, so you can filter, create, select related etc related models directly from parent model.
+
+!!!note
+    By default exposed QuerySet is already filtered to return only `Models` related to parent `Model`.
+    
+    So if you issue `post.categories.all()` you will get all categories related to that post, not all in table.
+
+!!!note
+    Note that when accessing QuerySet API methods through QuerysetProxy you don't 
+    need to use `objects` attribute like in normal queries.
+    
+    So note that it's `post.categories.all()` and **not** `post.categories.objects.all()`.
+    
+    To learn more about available QuerySet methods visit [queries][queries]
+
+!!!warning
+    Querying related models from ManyToMany cleans list of related models loaded on parent model:
+    
+    Example: `post.categories.first()` will set post.categories to list of 1 related model -> the one returned by first()
+    
+    Example 2: if post has 4 categories so `len(post.categories) == 4` calling `post.categories.limit(2).all()` 
+    -> will load only 2 children and now `assert len(post.categories) == 2`
+    
+    This happens for all QuerysetProxy methods returning data: `get`, `all` and `first` and in `get_or_create` if model already exists.
+    
+    Note that value returned by `create` or created in `get_or_create` and `update_or_create` 
+    if model does not exist will be added to relation list (not clearing it).
+
+#### get
+
+`get(**kwargs): -> Model` 
+
+To grab just one of related models filtered by name you can use `get(**kwargs)` method.
+
+```python
+# grab one category
+assert news == await post.categories.get(name="News")
+
+# note that method returns the category so you can grab this value
+# but it also modifies list of related models in place
+# so regardless of what was previously loaded on parent model
+# now it has only one value -> just loaded with get() call
+assert len(post.categories) == 1
+assert post.categories[0] == news
+
+```
+
+!!!tip
+    Read more in queries documentation [get][get]
+
+#### all
+
+`all(**kwargs) -> List[Optional["Model"]]`
+
+To get a list of related models use `all()` method. 
+
+Note that you can filter the queryset, select related, exclude fields etc. like in normal query.
+
+```python
+# with all Queryset methods - filtering, selecting columns, counting etc.
+await news.posts.filter(title__contains="M2M").all()
+await Category.objects.filter(posts__author=guido).get()
+
+# columns models of many to many relation can be prefetched
+news_posts = await news.posts.select_related("author").all()
+assert news_posts[0].author == guido
+```
+
+!!!tip
+    Read more in queries documentation [all][all]
+
+#### create
+
+`create(**kwargs): -> Model` 

 Create related `Model` directly from parent `Model`.

@ -134,64 +314,117 @@ assert len(await post.categories.all()) == 2
 # newly created instance already have relation persisted in the database
 ```

-!!!note
-    Note that when accessing QuerySet API methods through ManyToMany relation you don't 
-    need to use objects attribute like in normal queries.
-    
-    To learn more about available QuerySet methods visit [queries][queries]
+!!!tip
+    Read more in queries documentation [create][create]

-#### remove()

-Removal of the related model one by one.
+#### get_or_create

-Removes also the relation in the database.
-
-```python
-await news.posts.remove(post)
-```
-
-#### clear()
-
-Removal all related models in one call.
-
-Removes also the relation in the database.
-
-```python
-await news.posts.clear()
-```
-
-#### Other queryset methods
-
-When access directly the related `ManyToMany` field returns the list of related models.
-
-But at the same time it exposes full QuerySet API, so you can filter, create, select related etc.
-
-```python
-# Many to many relation exposes a list of columns models
-# and an API of the Queryset:
-assert news == await post.categories.get(name="News")
-
-# with all Queryset methods - filtering, selecting columns, counting etc.
-await news.posts.filter(title__contains="M2M").all()
-await Category.objects.filter(posts__author=guido).get()
-
-# columns models of many to many relation can be prefetched
-news_posts = await news.posts.select_related("author").all()
-assert news_posts[0].author == guido
-```
-
-Currently supported methods are:
+`get_or_create(**kwargs) -> Model`

 !!!tip
-    To learn more about available QuerySet methods visit [queries][queries]
+    Read more in queries documentation [get_or_create][get_or_create]

-##### get()
-##### all()
-##### filter()
-##### select_related()
-##### limit()
-##### offset()
-##### count()
-##### exists()
+#### update_or_create

-[queries]: ./queries.md
+`update_or_create(**kwargs) -> Model`
+
+!!!tip
+    Read more in queries documentation [update_or_create][update_or_create]
+
+#### filter
+
+`filter(**kwargs) -> QuerySet`
+
+!!!tip
+    Read more in queries documentation [filter][filter]
+
+#### exclude
+
+`exclude(**kwargs) -> QuerySet`
+
+!!!tip
+    Read more in queries documentation [exclude][exclude]
+
+#### select_related
+
+`select_related(related: Union[List, str]) -> QuerySet`
+
+!!!tip
+    Read more in queries documentation [select_related][select_related]
+
+#### prefetch_related
+
+`prefetch_related(related: Union[List, str]) -> QuerySet`
+
+!!!tip
+    Read more in queries documentation [prefetch_related][prefetch_related]
+
+#### limit
+
+`limit(limit_count: int) -> QuerySet`
+
+!!!tip
+    Read more in queries documentation [limit][limit]
+
+#### offset
+
+`offset(offset: int) -> QuerySet`
+
+!!!tip
+    Read more in queries documentation [offset][offset]
+
+#### count
+
+`count() -> int`
+
+!!!tip
+    Read more in queries documentation [count][count]
+
+#### exists
+
+`exists() -> bool`
+
+!!!tip
+    Read more in queries documentation [exists][exists]
+
+#### fields
+
+`fields(columns: Union[List, str, set, dict]) -> QuerySet`
+
+!!!tip
+    Read more in queries documentation [fields][fields]
+
+#### exclude_fields
+
+`exclude_fields(columns: Union[List, str, set, dict]) -> QuerySet`
+
+!!!tip
+    Read more in queries documentation [exclude_fields][exclude_fields]
+
+#### order_by
+
+`order_by(columns:Union[List, str]) -> QuerySet`
+
+!!!tip
+    Read more in queries documentation [order_by][order_by]
+
+
+[queries]: ./queries.md
+[querysetproxy]: ./relations.md#querysetproxy-methods
+[get]: ./queries.md#get
+[all]: ./queries.md#all
+[create]: ./queries.md#create
+[get_or_create]: ./queries.md#get_or_create
+[update_or_create]: ./queries.md#update_or_create
+[filter]: ./queries.md#filter
+[exclude]: ./queries.md#exclude
+[select_related]: ./queries.md#select_related
+[prefetch_related]: ./queries.md#prefetch_related
+[limit]: ./queries.md#limit
+[offset]: ./queries.md#offset
+[count]: ./queries.md#count
+[exists]: ./queries.md#exists
+[fields]: ./queries.md#fields
+[exclude_fields]: ./queries.md#exclude_fields
+[order_by]: ./queries.md#order_by