Type.__call__()#

#Type.__call__(
    self,
    *args: Type | TypeUnion | TypeIntersection,
    **kwargs: Any,
) -> Instance

#import relationalai as rai


# =====
# SETUP
# =====

model = rai.Model("BookModel")

# Declare Book, Fiction, and NonFiction types.
Book = model.Type("Book")
Fiction = model.Type("Fiction")
NonFiction = model.Type("NonFiction")

# Define some Book objects.
with model.rule():
    Book.add(Fiction, title="Foundation", author="Isaac Asimov")
    Book.add(NonFiction, title="Humble Pi", author="Matt Parker")


# =======
# EXAMPLE
# =======

# Call a Type to get an Instance that references objects of that type.
# Properties of objects are accessed as attributes of the Instance.
with model.query() as select:
    book = Book()
    response = select(book.title)

print(response.results)
#         title
# 0  Foundation
# 1   Humble Pi

# You can filter the objects referenced by the returned Instance by passing
# additional types as positional arguments and property values as keyword arguments.
with model.query() as select:
    # Get a reference to all Fiction books with the title "Foundation".
    book = Book(Fiction, title="Foundation")
    response = select(book.author)

print(response.results)
#          author
# 0  Isaac Asimov

# The above query is equivalent to the following:
with model.query() as select:
    book = Book()
    Fiction(book)  # Filter for Fiction books.
    book.title == "Foundation"  # Filter for books with the title "Foundation".
    response = select(book.author)

print(response.results)
#          author
# 0  Isaac Asimov

# When you pass multiple types as positional arguments, the Instance references
# objects that are instances of all the specified types.
with model.query() as select:
    book = Book(Fiction, NonFiction)
    response = select(book.title, book.author)

# The response is empty since no books are both Fiction and NonFiction.
print(response.results)