137 lines
6.5 KiB
Python
137 lines
6.5 KiB
Python
class Schema:
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def __init__(self, db_connection_method):
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self.execute = db_connection_method
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def get_schema_info(self, schema='public'):
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"""Fetches schema information directly."""
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tables_result = self.execute("""
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SELECT table_name
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FROM information_schema.tables
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WHERE table_schema = %s AND table_type = 'BASE TABLE';
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""", [schema])
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tables = [row['table_name'] for row in tables_result]
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schema_info = {}
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for table in tables:
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columns_result = self.execute("""
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SELECT column_name, data_type
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FROM information_schema.columns
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WHERE table_schema = %s AND table_name = %s
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ORDER BY ordinal_position;
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""", [schema, table])
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columns = [(row['column_name'], row['data_type']) for row in columns_result]
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primary_keys_result = self.execute("""
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SELECT kcu.column_name
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FROM information_schema.table_constraints tc
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JOIN information_schema.key_column_usage kcu
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ON tc.constraint_name = kcu.constraint_name AND tc.table_schema = kcu.table_schema
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WHERE tc.constraint_type = 'PRIMARY KEY' AND tc.table_schema = %s AND tc.table_name = %s;
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""", [schema, table])
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primary_keys = [row['column_name'] for row in primary_keys_result]
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foreign_keys_result = self.execute("""
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SELECT kcu.column_name AS fk_column, ccu.table_name AS referenced_table, ccu.column_name AS referenced_column
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FROM information_schema.table_constraints AS tc
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JOIN information_schema.key_column_usage AS kcu
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ON tc.constraint_name = kcu.constraint_name AND tc.table_schema = kcu.table_schema
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JOIN information_schema.constraint_column_usage AS ccu
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ON ccu.constraint_name = tc.constraint_name AND ccu.table_schema = tc.table_schema
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WHERE tc.constraint_type = 'FOREIGN KEY' AND tc.table_schema = %s AND tc.table_name = %s;
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""", [schema, table])
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foreign_keys = [(row['fk_column'], row['referenced_table'], row['referenced_column']) for row in foreign_keys_result]
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schema_info[table] = {
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'columns': columns,
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'primary_keys': primary_keys,
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'foreign_keys': foreign_keys
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}
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return schema_info
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def _map_data_type_for_sql(self, postgres_type):
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"""Maps PostgreSQL types to standard SQL types (simplified)."""
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return {
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'character varying': 'VARCHAR', 'varchar': 'VARCHAR', 'text': 'TEXT',
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'integer': 'INTEGER', 'bigint': 'BIGINT', 'boolean': 'BOOLEAN',
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'timestamp without time zone': 'TIMESTAMP', 'timestamp with time zone': 'TIMESTAMPTZ',
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'numeric': 'NUMERIC', 'real': 'REAL', 'date': 'DATE'
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}.get(postgres_type, postgres_type.upper())
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def _map_data_type(self, postgres_type):
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"""Maps PostgreSQL types to Mermaid ER diagram types."""
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type_mapping = {
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'integer': 'int', 'bigint': 'int', 'smallint': 'int',
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'character varying': 'string', 'varchar': 'string', 'text': 'string',
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'date': 'date', 'timestamp without time zone': 'datetime',
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'timestamp with time zone': 'datetime', 'boolean': 'bool',
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'numeric': 'float', 'real': 'float'
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}
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return type_mapping.get(postgres_type, 'string')
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def generate_mermaid_er(self, schema_info):
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"""Generates Mermaid ER diagram code from schema info."""
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mermaid_lines = [
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"%%{init: {'theme': 'default', 'themeCSS': '.er.entityBox { fill: transparent !important; } .er.attributeBoxEven { fill: transparent !important; } .er.attributeBoxOdd { fill: transparent !important; }'}}%%",
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"erDiagram"
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]
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# Sort tables for stable output
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sorted_tables = sorted(schema_info.keys())
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for table in sorted_tables:
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info = schema_info[table]
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mermaid_lines.append(f" {table} {{")
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pks = set(info.get('primary_keys', []))
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fks = {fk[0] for fk in info.get('foreign_keys', [])}
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for column_name, data_type in info['columns']:
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mermaid_data_type = self._map_data_type(data_type)
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markers = []
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if column_name in pks:
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markers.append("PK")
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if column_name in fks:
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markers.append("FK")
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marker_str = f" {','.join(markers)}" if markers else ""
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mermaid_lines.append(f" {mermaid_data_type} {column_name}{marker_str}")
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mermaid_lines.append(" }")
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for table in sorted_tables:
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info = schema_info[table]
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# Sort foreign keys for stable output
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sorted_fks = sorted(info.get('foreign_keys', []), key=lambda x: x[0])
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for fk_column, referenced_table, referenced_column in sorted_fks:
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relation = f" {referenced_table} ||--o{{ {table} : \"{fk_column}\""
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mermaid_lines.append(relation)
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return "\n".join(mermaid_lines)
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def generate_create_script(self, schema_info):
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"""Generates SQL CREATE TABLE scripts from schema info."""
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lines = []
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for table, info in schema_info.items():
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columns = info['columns']
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pks = info.get('primary_keys', [])
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fks = info['foreign_keys']
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column_defs = []
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for column_name, data_type in columns:
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sql_type = self._map_data_type_for_sql(data_type)
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column_defs.append(f' "{column_name}" {sql_type}')
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if pks:
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pk_columns = ", ".join(f'"{pk}"' for pk in pks)
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column_defs.append(f' PRIMARY KEY ({pk_columns})')
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columns_sql = ",\n".join(column_defs)
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create_stmt = f'CREATE TABLE "{table}" (\n{columns_sql}\n);'
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lines.append(create_stmt)
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for fk_column, ref_table, ref_col in fks:
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alter_stmt = (
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f'ALTER TABLE "{table}" ADD CONSTRAINT "fk_{table}_{fk_column}" '
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f'FOREIGN KEY ("{fk_column}") REFERENCES "{ref_table}" ("{ref_col}");'
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)
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lines.append(alter_stmt)
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lines.append("")
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return "\n".join(lines)
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