Работающий функционал

app/series_utils.py

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+#!/usr/bin/env python3
+"""Модуль для работы с сериями"""
+from db_utils import get_cursor
+
+
+def get_series_by_letter(letter=''):
+    """Возвращает серии по первой букве"""
+    conn, cur = get_cursor()
+
+    if letter:
+        cur.execute("""
+            SELECT s.id, s.name, s.name_hash,
+                   COUNT(DISTINCT b.id) as books_count
+            FROM series s
+            LEFT JOIN books b ON b.series_id = s.id
+            WHERE s.name ILIKE %s
+            GROUP BY s.id, s.name, s.name_hash
+            ORDER BY s.name
+            LIMIT 100
+        """, (letter + '%',))
+    else:
+        cur.execute("""
+            SELECT DISTINCT lower(substring(name, 1, 1)) as letter,
+                   COUNT(*) as cnt
+            FROM series
+            WHERE name ~ '^[а-яА-Яa-zA-Z]'
+            GROUP BY lower(substring(name, 1, 1))
+            ORDER BY letter
+        """)
+
+    result = cur.fetchall()
+    conn.close()
+    return result
+
+
+def get_series_by_hash(series_hash):
+    """Возвращает серию по хешу"""
+    conn, cur = get_cursor()
+
+    cur.execute("""
+        SELECT id, name, name_hash
+        FROM series
+        WHERE name_hash = %s
+    """, (series_hash,))
+
+    series = cur.fetchone()
+    conn.close()
+    return series
+
+
+def get_series_books(series_id):
+    """Возвращает все книги серии"""
+    conn, cur = get_cursor()
+
+    cur.execute("""
+        SELECT b.id, b.title, b.language, b.series_number,
+               string_agg(DISTINCT a.full_name, ', ' ORDER BY ba.position) as authors
+        FROM books b
+        JOIN book_authors ba ON ba.book_id = b.id
+        JOIN authors a ON a.id = ba.author_id
+        WHERE b.series_id = %s
+        GROUP BY b.id, b.title, b.language, b.series_number
+        ORDER BY b.series_number NULLS LAST, b.title
+    """, (series_id,))
+
+    books = cur.fetchall()
+    conn.close()
+    return books