[Python API] Not adding Var into the Model (addVar())

[Hexin Liu]

Please somebody help...

mdl=Model('SI')

x0=mdl.addVar(lb=0,name='x0')

Now if invoke x0, output :<gurobi.Var *Awaiting Model Update*>, which is good.

But, Invoke mdl, output: <gurobi.Model Continuous instance Structured Investment: 0 constrs, 0 vars, Parameter changes: LogFile=gurobi.log, CSIdleTimeout=1800>

Also, try x0+1, output AttributeError: b"Index out of range for attribute 'VarName'" instead of a Linear Expression

Again, try, mdl.getVars(), output [ ], an empty list.

Could anybody help me

[zinc...@gurobi.com]

You can force model update 

>> mdl.update()

to see the respective changes.

[Robert Luce]

Indeed you need to call Model.update() to populate the model with any queued changes, see also the section "Lazy Updates" here:

http://www.gurobi.com/documentation/8.1/refman/py_python_api_overview.html

Robert

[Hexin Liu]

Thank you Robert! 

[Hexin Liu]

Thank you! Exactly what is needed