Adding working version of api server with sqlite database

apiserver_with_sqlite.py

@@ -0,0 +1,159 @@
+from flask import Flask, request, jsonify, g
+import sqlite3
+
+make_table = r'''
+CREATE TABLE IF NOT EXISTS counters
+(counter_name TEXT PRIMARY KEY, counter_value INTEGER)
+'''
+
+add_counter = r'''
+INSERT INTO counters
+VALUES(?, ?)
+'''
+
+get_all_counters = r'''
+SELECT * FROM counters;
+'''
+
+increment_counter = r'''
+UPDATE counters
+SET counter_value = (SELECT counter_value FROM counters WHERE counter_name = ?) + 1
+WHERE counter_name = ?
+'''
+
+decrement_counter = r'''
+UPDATE counters
+SET counter_value = (SELECT counter_value FROM counters WHERE counter_name = ?) - 1
+WHERE counter_name = ?
+'''
+
+
+
+app = Flask(__name__)
+
+def get_db():
+    db = getattr(g, "_database", None)
+
+    if db is None:
+        db = g._database = sqlite3.connect("counters.db")
+        db.execute(make_table)
+
+    return db
+
+def get_all_counters_as_dict():
+    cursor = get_db().execute(get_all_counters)
+    all_counters = cursor.fetchall()
+
+    print(all_counters)
+
+    return {counter[0]:counter[1] for counter in all_counters}
+
+def add_counter_to_db(counter_name, counter_initial_value):
+    cursor = get_db().execute(add_counter, [counter_name, counter_initial_value])
+    get_db().commit()
+
+def modify_counter_in_db(counter_name, increment):
+    if increment:
+        get_db().execute(increment_counter, [counter_name, counter_name])
+    else:
+        get_db().execute(decrement_counter, [counter_name, counter_name])
+
+    get_db().commit()
+
+@app.route("/counters", methods=['GET', 'POST'])
+def handle_counters_endpoint():
+    if request.method == 'GET':
+        response_dict = {
+            'all_counters': get_all_counters_as_dict()
+        }
+        return jsonify(response_dict), 200
+    elif request.method == 'POST':
+        if request.content_type == 'application/json':
+            body = request.get_json()
+
+            if not "new_counter_name" in body.keys() or not "new_counter_starting_value" in body.keys():
+                error_response = {
+                    'status': 'ERROR',
+                    'reason': 'Body for posting to /counters endpoint must contain both new_counter_name and new_counter_starting_value',
+                    'input_body': body
+                }
+                return jsonify(error_response), 400
+
+            add_counter_to_db(request.get_json()['new_counter_name'], request.get_json()['new_counter_starting_value'])
+            return jsonify({'status': 'OK'}), 200
+        else:
+            error_response = {
+                'status': 'ERROR',
+                'reason': 'Content Type for endpoint /counters must be application/json'
+            }
+            return jsonify(error_response), 400
+
+@app.route("/counters/<counter_name>", methods=['GET'])
+def handle_counters_subcounter_endpoint(counter_name):
+    all_counters = get_all_counters_as_dict()
+    if not counter_name in all_counters.keys():
+        error_response = {
+            'status': 'ERROR',
+            'reason': 'Counter name {counter} does not exist'.format(counter=counter_name)
+        }
+        return jsonify(error_response), 404
+    
+    data_response = {
+        'counter_name': counter_name,
+        'counter_value': all_counters[counter_name]
+    }
+
+    return jsonify(data_response), 200
+
+@app.route("/counters/<counter_name>/increment", methods=['POST'])
+def handle_counters_subcounter_increment(counter_name):
+    all_counters = get_all_counters_as_dict()
+
+    if not counter_name in all_counters.keys():
+        error_response = {
+            'status': 'ERROR',
+            'reason': 'Counter name {counter} does not exist'.format(counter=counter_name)
+        }
+        return jsonify(error_response), 404
+    
+    data_response = {
+        'counter_name': counter_name,
+        'old_value': all_counters[counter_name],
+        'new_value': all_counters[counter_name] + 1
+    }
+
+    modify_counter_in_db(counter_name, True)
+
+    return jsonify(data_response), 200
+
+@app.route("/counters/<counter_name>/decrement", methods=['POST'])
+def handle_counters_subcounter_decrement(counter_name):
+    all_counters = get_all_counters_as_dict()
+
+    if not counter_name in all_counters.keys():
+        error_response = {
+            'status': 'ERROR',
+            'reason': 'Counter name {counter} does not exist'.format(counter=counter_name)
+        }
+        return jsonify(error_response), 404
+    
+    data_response = {
+        'counter_name': counter_name,
+        'old_value': all_counters[counter_name],
+        'new_value': all_counters[counter_name] - 1
+    }
+
+    modify_counter_in_db(counter_name, False)
+
+    return jsonify(data_response), 200
+    
+@app.teardown_appcontext
+def close_connection(exception):
+    db = getattr(g, '_database', None)
+
+    if db is not None:
+        db.close()  
+
+if __name__ == '__main__':
+    app.run(debug=True)
+