View of Constraints and Decision Variables in Pyomo

After defining your model by putting the following statement in your code (wherever you want before or after solve command) your model with all the objects has been printed:

model.pprint() 

If you like to print constraints or variables individually:

model.cons1.pprint()  # For entire ConstraintList
print(model.cons2[i].expr)  # For only one index of ConstraintList
model.write() # To write the model into a file using .nl format

Assuming that model is the model that you defined and cons1 and cons2 are two ConstraintsList in that model.