Starting code for writing to Postgres db.

db_tools/db_writer.py

@@ -0,0 +1,103 @@
+#! env/bin/python3
+
+# import the psycopg2 database adapter for PostgreSQL
+from psycopg2 import connect, Error
+import json
+from psycopg2.extras import Json
+from psycopg2.extras import json as psycop_json
+import sys
+
+def connect_db(db: str,host: str,user: str,passwd: str):
+    try:
+        # declare a new PostgreSQL connection object
+        conn = connect(
+            dbname = db,
+            user = user,
+            host = host,
+            password = passwd,
+            # attempt to connect for 3 seconds then raise exception
+            connect_timeout = 3
+        )
+        cur = conn.cursor()
+
+    except (Exception, Error) as err:
+        #print ("\npsycopg2 connect error:", err)
+        #conn = None
+        cur = None
+    return cur
+
+# use Python's open() function to load the JSON data
+with open('postgres-records.json') as json_data:
+
+    # use load() rather than loads() for JSON files
+    record_list = json.load(json_data)
+
+# concatenate an SQL string
+sql_string = 'INSERT INTO {} '.format( table_name )
+
+# if record list then get column names from first key
+if type(record_list) == list:
+    first_record = record_list[0]
+
+    columns = list(first_record.keys())
+    print ("\ncolumn names:", columns)
+
+# if just one dict obj or nested JSON dict
+else:
+    print ("Needs to be an array of JSON objects")
+    sys.exit()
+
+# enclose the column names within parenthesis
+sql_string += "(" + ', '.join(columns) + ")\nVALUES "
+
+# only attempt to execute SQL if cursor is valid
+if cur != None:
+
+    try:
+        cur.execute( sql_string )
+        conn.commit()
+
+        print ('\nfinished INSERT INTO execution')
+
+    except (Exception, Error) as error:
+        print("\nexecute_sql() error:", error)
+        conn.rollback()
+
+    # close the cursor and connection
+    cur.close()
+    conn.close()
+
+######################################################3
+
+import psycopg2
+from config import config
+
+
+def insert_vendor(vendor_name):
+    """ insert a new vendor into the vendors table """
+    sql = """INSERT INTO vendors(vendor_name)
+             VALUES(%s) RETURNING vendor_id;"""
+    conn = None
+    vendor_id = None
+    try:
+        # read database configuration
+        params = config()
+        # connect to the PostgreSQL database
+        conn = psycopg2.connect(**params)
+        # create a new cursor
+        cur = conn.cursor()
+        # execute the INSERT statement
+        cur.execute(sql, (vendor_name,))
+        # get the generated id back
+        vendor_id = cur.fetchone()[0]
+        # commit the changes to the database
+        conn.commit()
+        # close communication with the database
+        cur.close()
+    except (Exception, psycopg2.DatabaseError) as error:
+        print(error)
+    finally:
+        if conn is not None:
+            conn.close()
+
+    return vendor_id