def create_index(self, field_to_index: str) -> None:
index_tree = BPlusTree(
f'db_files/{self.name}_order_by_{field_to_index}.db', order=50)
db_data = read_from_json("db_files/db.json")
if field_to_index in db_data[self.name]['indexes']:
return
num_of_files = db_data[self.name]['num of files']
primary_key = db_data[self.name]['primary key']
if primary_key == field_to_index:
for file_num in range(num_of_files):
path = f"db_files/{self.name}_{file_num + 1}.json"
file_data = read_from_json(path)
for k in file_data.keys():
print(k)
index_tree[k] = path
else:
for file_num in range(num_of_files):
path = f"db_files/{self.name}_{file_num + 1}.json"
file_data = read_from_json(path)
for v in file_data.values():
print(v)
index_tree[v[field_to_index]] = path
index_tree.close()
db_data[self.name]['indexes'] += field_to_index
def insert_record(self, values: Dict[str, Any]) -> None:
db_data = read_from_json("db_files/db.json")
flag = None
primary_key = db_data[self.name]['primary key']
try:
flag = self.get_record(values[primary_key])
except:
db_data = read_from_json("db_files/db.json")
primary_key = get_primary_key(db_data, self.name)
record_to_insert = {
values[primary_key]:
{k: str(v)
for k, v in values.items() if k != primary_key}
}
if end_place_in_file(
db_data,
self.name) and db_data[self.name]['num of lines'] != 0:
db_data[self.name]['num of files'] += 1
write_to_json(
f"db_files/{self.name}_{db_data[self.name]['num of files']}.json",
record_to_insert)
else:
add_to_json(
f"db_files/{self.name}_{db_data[self.name]['num of files']}.json",
record_to_insert)
if flag is not None:
raise ValueError
db_data[self.name]['num of lines'] += 1
write_to_json("db_files/db.json", db_data)
def get_record(self, key: Any) -> Dict[str, Any]:
db_data = read_from_json("db_files/db.json")
num_of_files = db_data[self.name]['num of files']
for file_num in range(num_of_files):
file_data = read_from_json(
f"db_files/{self.name}_{file_num + 1}.json")
for k in file_data.keys():
if k == str(key):
return file_data[k]
else:
raise ValueError
def update_record(self, key: Any, values: Dict[str, Any]) -> None:
db_data = read_from_json("db_files/db.json")
num_of_files = db_data[self.name]['num of files']
for file_num in range(num_of_files):
file_data = read_from_json(
f"db_files/{self.name}_{file_num + 1}.json")
for k in file_data.keys():
if k == str(key):
for field in values.keys():
file_data[k][field] = values[field]
write_to_json(f"db_files/{self.name}_{file_num + 1}.json",
file_data)
return
raise ValueError
def delete_table_from_db(table_name):
db_data = read_from_json("db_files/db.json")
num_of_files = db_data[table_name]['num of files']
del (db_data[table_name])
db_data['num of tables'] -= 1
write_to_json("db_files/db.json", db_data)
return num_of_files
def create_table(self, table_name: str, fields: List[DBField],
key_field_name: str) -> DBTable:
if os.path.isfile(f"db_files/{table_name}_1.json"):
raise ValueError
if key_field_name not in [field.name for field in fields]:
raise ValueError
db_data = read_from_json("db_files/db.json")
if table_name in db_data.keys():
raise ValueError
write_to_json(f"db_files/{table_name}_1.json", {})
db_data['num of tables'] += 1
db_data[table_name] = \
{'num of files': 1,
'num of lines': 0,
'fields': convert_from_DBfield_to_dict(fields),
'primary key': key_field_name,
'indexes': []
}
write_to_json("db_files/db.json", db_data)
table = DBTable(table_name, fields, key_field_name)
table.create_index(key_field_name)
return table
def query_table(self, criteria: List[SelectionCriteria]) \
-> List[Dict[str, Any]]:
db_data = read_from_json("db_files/db.json")
num = get_num_of_files(db_data, self.name)
pk = get_primary_key(db_data, self.name)
return treats_relevant(num, self.name, criteria, pk, False)
def delete_record(self, key: Any) -> None:
db_data = read_from_json("db_files/db.json")
num_of_files = db_data[self.name]['num of files']
flag = False
for file_num in range(num_of_files):
file_data = read_from_json(
f"db_files/{self.name}_{file_num + 1}.json")
for k in file_data.keys():
if k == str(key):
flag = True
del_key = k
break
if flag:
del file_data[del_key]
write_to_json(f"db_files/{self.name}_{file_num + 1}.json",
file_data)
if not flag:
raise ValueError
db_data[self.name]['num of lines'] -= 1
write_to_json("db_files/db.json", db_data)
def treats_relevant(num, table_name, criteria, primary_key, delete):
relevants = []
for file_num in range(num):
file_data = read_from_json(
f"db_files/{table_name}_{file_num + 1}.json")
for k, v in file_data.items():
flag = 0
for c in criteria:
if c.field_name == primary_key:
if not ops[c.operator](int(k), int(c.value)):
flag = 1
break
else:
if not ops[c.operator](v[c.field_name], c.value):
flag = 1
break
if not flag:
if not delete:
relevants.append(v)
else:
relevants.append(k)
if delete:
delete_relevant_keys(relevants, file_data, table_name, file_num)
# update_lines(table_name, num_of_deletes, file_data, file_num)
return relevants
def update_data(table_name, num, file_data, file_num):
db_data = read_from_json("db_files/db.json")
db_data[table_name]['num of lines'] -= num
write_to_json(f"db_files/{table_name}_{file_num + 1}.json", file_data)
write_to_json("db_files/db.json", db_data)
def get_tables_names(self) -> List[Any]:
db_data = read_from_json("db_files/db.json")
return [key for key in db_data.keys() if key != 'num of tables']
def get_table(self, table_name: str) -> DBTable:
db_data = read_from_json("db_files/db.json")
return DBTable(
table_name,
convert_from_dict_to_DBfield(db_data[table_name]['fields']),
db_data[table_name]['primary key'])
def num_tables(self) -> int:
db_data = read_from_json("db_files/db.json")
return db_data['num of tables']
def delete_records(self, criteria: List[SelectionCriteria]) -> None:
db_data = read_from_json("db_files/db.json")
num = get_num_of_files(db_data, self.name)
pk = get_primary_key(db_data, self.name)
treats_relevant(num, self.name, criteria, pk, True)
def count(self) -> int:
db_data = read_from_json("db_files/db.json")
return db_data[self.name]['num of lines']
