Writing model to file

[fa-bien]

I just found out that there have been breaking changes, as described at https://discourse.julialang.org/t/ann-upcoming-breaking-changes-to-cplex-jl-and-gurobi-jl/47814/7

I am now upgrading "old" code to the new version but I cannot find how to write a model to a file. I used to do the following: write_model(backend(model).inner, filename)

Now my understanding is that I need to write something like
GRBwrite(model, filename)

However if I do that I get an error message:

ERROR: MethodError: no method matching write_to_file(::JuMP.Model, ::String) Closest candidates are: write_to_file(::Union{MathOptInterface.Utilities.UniversalFallback{MathOptInterface.FileFormats.MOF.InnerModel{Float64}}, MathOptInterface.FileFormats.CBF.Model, MathOptInterface.FileFormats.LP.Model, MathOptInterface.FileFormats.MPS.Model, MathOptInterface.FileFormats.SDPA.Model}, ::String) at /home/fabien/.julia/packages/MathOptInterface/ZJFKw/src/FileFormats/FileFormats.jl:99

[fa-bien]

Never mind, solved it by (i) using direct_model() and (ii) using GRBwrite(backend(model), filename)

[odow]

You should also be able to use JuMP.write_to_file:

using JuMP, Gurobi
model = Model(Gurobi.Optimizer)
# stuff...
write_to_file(model, "my_model.mps")