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WordSelector — Example 1

The WordSelector class in loglan_core\addons\word_selector.py is used to construct complex queries to select words from a database. Here's an example usage of this class:

# Import the WordSelector class
from loglan_core.addons.word_selector import WordSelector

WordSelector Initialization

When creating WordSelector object, several parameters can be used:

  • model: class of the words to be filtered (BaseWord by default). It is used to return words by associated class.

The specified class must inherit from BaseWord, otherwise a ValueError exception will be raised if the disable_model_check option is False.

  • is_sqlite: boolean that indicates whether the underlying database is SQLite. If True, the WordSelector will use SQLite-compatible SQL syntax.

You must explicitly specify is_sqlite option when working with SQLite in order for case-sensitive search features to work correctly.

  • case_sensitive: boolean that indicates whether the search is case-sensitive. If True, the WordSelector will use case-sensitive search in the underlying database.

  • disable_model_check: boolean that indicates whether the WordSelector should perform a model check. If True, the WordSelector will not perform a model check.

Create WordSelector instance

The simplest way to create a WordSelector object is to use the WordSelector constructor:

ws = WordSelector()

By this way, we create a new WordSelector instance that will select all words from database.

Apply Filters

Also, we can apply filters to our query. For example, to select words associated with a specific event, use the by_event method:

ws_event = WordSelector().by_event(event_id=1)

For filtering words by a specific name, use the by_name method:

ws_by_name = WordSelector().by_name(name='proga')

Similarly, we can filter words by a specific key using the by_key method:

ws_by_key = WordSelector().by_key(key='program')

Or use the by_type method for filtering words by a specific type:

ws_by_type = WordSelector().by_type("Afx")

All these methods return a new instance of WordSelector with the filter applied.

We can also combine all these filters together:

ws_combined = WordSelector().by_event(event_id=1).by_name(name='proga')

This will select words that are associated with the specified event AND have the specified name.

Get Derivatives

Three methods are available for getting derivatives of the word by word_id:

get_derivatives_of, get_complexes_of and get_affixes_of

ws_derivatives = WordSelector().get_derivatives_of(word_id=1)
ws_derivatives = WordSelector().get_complexes_of(word_id=1)
ws_derivatives = WordSelector().get_affixes_of(word_id=1)

You can combine them with filters as well.

Get Results from WordSelector

The WordSelector object returns a classic SQLAlchemy Select Object, so we can use it as normal within a session, like this:

all_words = session.scalars(ws_combined.get_statement()).all()
first_word = session.scalar(ws_combined.get_statement())

Also, we can use the internal all, scalar or fetchmany methods:

all_words = ws_combined.all(session)
first_word = ws_combined.scalar(session)
first_five_words = ws_combined.fetchmany(session, size=5)

These methods return a list of Word Objects or a single Word Object that match the applied filters.