如何访问pyomo中的目标函数值？

pip install pyomo

from pyomo.environ import *

model = ConcreteModel()

model.x = Var()
model.y = Var()
model.Constraint1 = Constraint(expr=model.x + model.y <= 10)

model.obj = Objective(expr=model.x + 2*model.y, sense=minimize)

solver = SolverFactory('glpk')
solver.solve(model)

objective_value = model.obj.value
print("目标函数的值为:", objective_value)