Flask应用中全局变量的正确管理与flask.g的使用指南

from flask import Flask, jsonify
import trainer

app = Flask(__name__)
LISTEN_PORT = 5000 # Example port

@app.route('/start/<int:id>', methods=['POST'])
def apifunc(id):
   result = trainer.consume(id)
   return jsonify(result)

if __name__ == '__main__':
    app.run(debug=True, port=LISTEN_PORT, threaded=True, use_reloader=False)

from utilities import function1

def consume(id):
  # 假设id在这里被用于某种计算，并影响function1的参数
  agg1_value = id * 2 # 示例：根据id计算agg1
  value = function1(agg1_value)
  # ... some codes...
  return value

aggregate = 30 # 模块级别的全局变量

def function1(agg1):
  global aggregate # 声明要修改模块级别的aggregate
  # ... some codes that might modify aggregate ...
  # aggregate = agg1 # 示例：修改aggregate
  print(f"Current aggregate value: {aggregate}")
  return aggregate # 假设返回修改后的aggregate

from flask import Flask, g, jsonify, request

app = Flask(__name__)

@app.before_request
def setup_request_globals():
    """在每个请求开始前初始化或设置g对象上的数据"""
    # 假设我们想为每个请求设置一个初始的aggregate值
    # 或者从请求参数中获取
    g.aggregate = 30
    # 也可以根据请求数据设置
    # if 'initial_agg' in request.json:
    #     g.aggregate = request.json['initial_agg']
    print(f"Request started. Initial g.aggregate: {g.aggregate}")

@app.route('/start/<int:id>', methods=['POST'])
def apifunc(id):
   # 在这里，g.aggregate已经被setup_request_globals设置
   # 或者可以在这里根据需要进一步修改
   g.aggregate += id # 示例：修改g.aggregate
   result = trainer_with_g.consume(id) # 调用使用g的trainer模块
   return jsonify({"message": "Processed", "final_aggregate": g.aggregate, "trainer_result": result})

# ... 其他路由和应用配置

from flask import g

def function1_with_g(agg1):
  # 检查g.aggregate是否存在，如果不存在则设置默认值
  if not hasattr(g, 'aggregate'):
      g.aggregate = 0 # 或其他默认值
      print("g.aggregate not found, initialized to 0.")

  # 使用和修改g.aggregate
  g.aggregate = agg1 # 示例：根据传入参数修改g.aggregate
  print(f"Inside function1_with_g. g.aggregate updated to: {g.aggregate}")
  return g.aggregate

from utilities_with_g import function1_with_g

def consume(id):
  agg1_value = id * 2
  value = function1_with_g(agg1_value)
  # ... some codes...
  return value

from flask import Flask, g, jsonify, request
import trainer_with_g # 导入使用g的trainer模块

app = Flask(__name__)
LISTEN_PORT = 5000

@app.before_request
def setup_request_globals():
    """在每个请求开始前初始化g对象上的数据"""
    # 可以从请求中获取数据来初始化g.aggregate
    # 或者设置一个默认值
    g.aggregate = request.json.get('initial_aggregate', 30) if request.is_json else 30
    print(f"Request started. Initial g.aggregate for this request: {g.aggregate}")

@app.route('/start/<int:id>', methods=['POST'])
def apifunc(id):
   # g.aggregate在这里已经初始化，并可以被修改
   print(f"Before trainer call, g.aggregate: {g.aggregate}")
   trainer_result = trainer_with_g.consume(id)
   print(f"After trainer call, g.aggregate: {g.aggregate}")
   return jsonify({
       "message": "Processed successfully",
       "request_id": id,
       "final_aggregate_in_request_context": g.aggregate,
       "trainer_processed_value": trainer_result
   })

if __name__ == '__main__':
    app.run(debug=True, port=LISTEN_PORT, threaded=True, use_reloader=False)

from utilities_with_g import function1_with_g
from flask import g

def consume(id):
  # 可以在这里访问或修改g.aggregate
  print(f"In trainer_with_g.consume, g.aggregate before modification: {g.aggregate}")
  g.aggregate += 5 # 示例：在trainer层修改g.aggregate
  agg1_value = id * 2
  value = function1_with_g(agg1_value)
  print(f"In trainer_with_g.consume, g.aggregate after function1_with_g: {g.aggregate}")
  return value

from flask import g

def function1_with_g(agg1):
  # 确保g.aggregate存在，如果不存在（例如，在单元测试中直接调用），则提供默认值
  if not hasattr(g, 'aggregate'):
      print("Warning: g.aggregate not found in utilities_with_g.function1_with_g, initializing to 0.")
      g.aggregate = 0

  print(f"In utilities_with_g.function1_with_g, g.aggregate before modification: {g.aggregate}")
  g.aggregate = agg1 # 根据传入参数更新g.aggregate
  print(f"In utilities_with_g.function1_with_g, g.aggregate after modification: {g.aggregate}")
  return g.aggregate