pg-dbconnect 2.4.1

A utility for PostgreSQL/PostGIS integration and data handling

DBConnect Module

Version: v2.3.1

---

Overview

DBConnect is a lightweight ETL helper module for Python that simplifies:

• Connecting to PostgreSQL databases
• Reading various file formats into Pandas/GeoPandas DataFrames
• Dumping data to PostgreSQL/PostGIS
• Extracting data from PostgreSQL
• Executing stored procedures
• Managing database environment configurations (db_config.json)

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Features

1. Connector — Manage DB connections, test connectivity, check if tables exist.
2. EnvironmentManager — Add, update, delete, and list database environment configurations.
3. FileReader — Read .csv, .shp, .xlsx and more into DataFrames.
4. DataDumper — Optimized loading of Pandas or GeoPandas data into PostgreSQL/PostGIS.
5. DatabaseExtractor — Query data from PostgreSQL into DataFrames.
6. StoredProcedureExecutor — Run PostgreSQL stored procedures.

---

Configuration

File: db_config.json

{
    "environments": {
        "dev": {
            "NAME": "my_db",
            "HOST": "localhost",
            "PORT": "5432",
            "USER": "username",
            "PASS": "password"
        }
    }
}

Example Usage (v2.3.1 — New Recommended Usage)

In v2.1.0, helper classes are created through factory methods on the main DBConnect object. You no longer need to pass the DBConnect instance into its own sub-classes.

1. Connect to a Database

from dbconnect import DBConnect

db = DBConnect()

# Create connector for 'dev' environment
conn = db.connector("dev")

if conn.test_connection():
    conn.connect()

conn.disconnect()

2. Check if a Table Exists

if conn.table_exists("my_table", schema="public"):
    print("Table exists!")
else:
    print("Table not found.")

3. Manage Environments (EnvironmentManager)

env_mgr = db.environment_manager()

# List environments
print(env_mgr.list_environments())

# Add environment
env_mgr.add_environment("staging", {
    "NAME": "staging_db",
    "HOST": "localhost",
    "PORT": "5432",
    "USER": "stag_user",
    "PASS": "stag_pass"
})

# Update environment
env_mgr.update_environment("staging", "HOST", "192.168.1.10")

# Delete environment
env_mgr.delete_environment("staging")

4. Read Files into DataFrames

reader = db.file_reader()
df_csv = reader.read_file("/data", "mydata.csv")
df_excel = reader.read_file("/data", "mydata.xlsx", file_sheetname="Sheet1")
gdf_shp = reader.read_file("/data", "myshapefile.shp")

5. Dump Data to PostgreSQL

dumper = db.data_dumper(conn.conn, conn.engine)
dumper.data_import(df_csv, "my_table", schema="public")

6. Extract Data from PostgreSQL

Using method .get_data

extractor = db.database_extractor(conn.conn, conn.engine)
df_db = extractor.get_data("my_table", "public", columns=["id", "name"], row_limit=10)

Using method .get_data_with_custom_query

Executes a custom SQL query and returns the results as a Pandas DataFrame.

By default (safe_mode=True), only read-only queries are allowed:

• Plain SELECT ... queries
• WITH ... SELECT queries (CTEs — Common Table Expressions)

Any query containing destructive keywords such as DROP, DELETE, UPDATE, INSERT, ALTER, or TRUNCATE will be blocked in safe mode.

Simple SELECT

df = extractor.get_data_with_custom_query(
    "SELECT id, name FROM public.people LIMIT 5;"
)

CTE Example

df = extractor.get_data_with_custom_query("""
WITH recent AS (
    SELECT * FROM logs ORDER BY ts DESC LIMIT 10
)
SELECT * FROM recent;
""")

Disable Safe Mode (Dangerous) This is highly discouraged. Use unless needed.

df = extractor.get_data_with_custom_query(
    "DROP TABLE public.people;",
    safe_mode=False
)

7. Execute Stored Procedures

The DatabaseStoredProcedureExecutor now supports a simplified, unified API for running stored procedures:

• execute_sp() → Executes a single stored procedure (with or without parameters).
• execute_multiple_sps() → Executes multiple stored procedures in order, in a single transaction.
  • Supports mixed calls (some with parameters, some without).
  • Uses ? placeholders for parameters for clarity and safety.

---

7.1 Single Stored Procedure

No Parameters

sp_exec = db.stored_procedure_executor(conn.environment_creds)

Run a procedure with no parameters

sp_exec.execute_sp("processing.refresh_summary()")

With Parameters Call with parameters using ? placeholders

sp_exec.execute_sp("processing.insert_dummy_person(?,?,?)", ["Alice", "Admin", 1])

Internally, ? is safely replaced with %s for psycopg2 binding, preventing SQL injection.

7.2 Multiple Stored Procedures in Order

All Without Parameters

sp_exec.execute_multiple_sps([
    ("processing.refresh_summary()", None),
    ("processing.update_statistics()", None)
])

All With Parameters

sp_exec.execute_multiple_sps([
    ("processing.insert_dummy_person(?,?,?)", ["Bob", "User", 2]),
    ("processing.insert_dummy_person(?)", ["Charlie"])
])

Mixed Without and With Parameterss

sp_exec.execute_multiple_sps([
    ("processing.refresh_summary()", None),                         # no params
    ("processing.insert_dummy_person(?,?)", ["David", "Guest"]),    # with params
    ("processing.update_statistics()", None)                        # no params
])

Notes

• Parameter Placeholders:
  Always use ? in sp_template for parameters.
  Example: "schema.proc_name(?,?)", then pass the values as a list or tuple.

• Transaction Handling:

  • By default (stop_on_error=True), if any stored procedure fails, all previous SPs are rolled back and execution stops.
  • Set stop_on_error=False to rollback only the failing SP and continue executing the rest.

• OUT Parameters:
  If the procedure returns OUT parameters, they will be printed and returned by the function.
  If not, you will see "No OUT parameters returned.".

---

Example Usage (v2.0.0 — Older Version for Reference)

Before v2.1.0, sub-classes required passing the DBConnect instance into their constructors.

1. Connect to a Database

from dbconnect import DBConnect

# Create a connector
conn = DBConnect.Connector(environment="dev")

# Test connection before connecting
if conn.test_connection():
    conn.connect()

# Disconnect later
conn.disconnect()

2. Check if a Table Exists

if conn.table_exists("my_table", schema="public"):
    print("Table exists!")
else:
    print("Table not found.")

3. Manage Environments (EnvironmentManager)

db = DBConnect()
env_mgr = db.EnvironmentManager(db) #Pass the DBConnect as Parent Class

# List environments
print(env_mgr.list_environments())

# Add environment
env_mgr.add_environment("staging", {
    "NAME": "staging_db",
    "HOST": "localhost",
    "PORT": "5432",
    "USER": "stag_user",
    "PASS": "stag_pass"
})

# Update environment value
env_mgr.update_environment("staging", "HOST", "192.168.1.10")

# Delete environment
env_mgr.delete_environment("staging")

4. Read Files into DataFrames

reader = DBConnect.FileReader()
df_csv = reader.read_file("/data", "mydata.csv")
df_excel = reader.read_file("/data", "mydata.xlsx", file_sheetname="Sheet1")
gdf_shp = reader.read_file("/data", "myshapefile.shp")

5. Dump Data to PostgreSQL

dumper = DBConnect.DataDumper(conn.conn, conn.engine)
dumper.data_import(df_csv, "my_table", schema="public")

6. Extract Data from PostgreSQL

extractor = DBConnect.DatabaseExtractor(conn.conn, conn.engine)
df_db = extractor.get_data("my_table", "public", columns=["id", "name"], row_limit=10)

7. Execute Stored Procedure

sp_executor = DBConnect.DatabaseStoredProcedureExecutor(conn.environment_creds)
sp_executor.execute_sp("refresh_materialized_views")

---

Versioning

v[MAJOR].[MINOR].[PATCH]

MAJOR (0) →Increment when you make breaking changes that are not backward-compatible.

• Example: Renaming methods, changing method arguments, restructuring the module.

MINOR (1) → Increment when you add new features that are backward-compatible.

• Example: Adding test_connection() and table_exists() without removing anything.

PATCH (2) → Increment when you fix bugs, make small improvements, or do documentation-only updates.

• Example: Cleaning up code style, fixing typos in docstrings, improving error - handling.

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Changelog

v2.4.1 — Latest Update

• class FileReader — Added dedicated public method for reading a specific geodatabase layer:
  • New method read_gdb_layer(gdb_path, layer_name) allows loading a GeoDataFrame from a specific .gdb or .gdb.zip layer without relying on internal _read_gdb_layer() calls.
  • Keeps _read_gdb_layer() as an internal helper while providing a clean public API for layer-level reads.
  • ----------------- Example usage -----------------

    fr = FileReader()
    
    # Directly read a specific GDB layer
    gdf_layer = fr.read_gdb_layer("data/city_roads.gdb", "RoadCenterlines")
    print(gdf_layer.head())
    

v2.4.0

• class FileReader — Major refactor to unify geodatabase handling:
  • Added support for both .gdb directories and zipped .gdb.zip files using GDAL VSI paths.
  • Introduced new helper methods:
    • get_layers(gdb_path) — List all layers in a geodatabase.
    • layer_statistics(gdb_path, layer_name) — Retrieve quick statistics for a specific layer.
  • read_file() now automatically detects .gdb and .gdb.zip and can default to reading the first layer if no layer name is provided.
  • Improved error handling for missing layers and unsupported formats.
  • ----------------- Example usage -----------------

    fr = FileReader()
    
    # CSV example
    df_csv = fr.read_file("data/table.csv")
    
    # Read specific GDB layer via read_file()
    gdf = fr.read_file("data/city_roads.gdb.zip", file_layer="Roads")
    
    # List available layers
    layers = fr.get_layers("data/city_roads.gdb.zip")
    
    # Get quick stats for a layer
    stats = fr.layer_statistics("data/city_roads.gdb", "Parcels")
    
    print(layers)
    print(stats)
    

v2.1.0

• Factory Pattern for Creating Helper Classes:
  • db.connector("dev") instead of DBConnect.Connector(db, "dev")
  • db.environment_manager() instead of DBConnect.EnvironmentManager(db)
• Optimized DataDumper:
  • Added chunked inserts (chunksize) and method="multi" for faster large data loads.
• DatabaseExtractor Enhancements:
  • Added get_data_with_custom_query() method with safe_mode flag (enabled by default).
  • Safe mode allows only read-only queries (SELECT and CTEs: WITH ... SELECT).
  • Blocks destructive keywords like DROP, DELETE, UPDATE, INSERT, ALTER, and TRUNCATE in safe mode.
  • Added ability to disable safe mode (safe_mode=False) for advanced use cases.
• Stored Procedure Executor:
  • Unified API for stored procedures into two methods:
    • execute_sp() → Single SP execution, handles both with and without parameters.
    • execute_multiple_sps() → Multiple SP execution, supports mixed calls with and without parameters in one transaction.
  • Supports ? placeholders for parameters for easier reading and safe parameter binding.
  • Improved transaction handling with stop_on_error option.
• Cleaner API:
  • No more passing DBConnect instance into its own sub-classes.
  • Centralized config path management in the main DBConnect object.
• Improved Maintainability:
  • Standardized helper object creation.
  • Easier for testing and scripting.

---

v2.0.0

• Integrated EnvironmentManager for CRUD operations on db_config.json.
• Centralized config file path initialization in DBConnect so all classes share the same path.
• Improved Connector:
  • Added test_connection() method.
  • Added table_exists() method.
• Applied PEP8 cleanup and improved docstrings for maintainability.
• Consolidated config file handling for all related classes to ensure consistency.

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Planned Features

• Package DBConnect Module to PyP making it available online.
• Add support for .parquet in FileReader.
• Add UPSERT support in DataDumper.
• Add JSON import/export helpers.
• Replace print statements with configurable logging.
• Add connection pooling for high-performance workloads.