# Unable to delete constraints stored in dictionaries using JuMP@.constraint macro
**URL:** https://discourse.julialang.org/t/unable-to-delete-constraints-stored-in-dictionaries-using-jump-constraint-macro/43920
**Category:** Optimization (Mathematical)
**Tags:** jump, optimization
**Created:** [July 29, 2020, 8:45pm UTC](https://discourse.julialang.org/t/unable-to-delete-constraints-stored-in-dictionaries-using-jump-constraint-macro/43920 "2020-07-29T20:45:12Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@srajan76](https://discourse.julialang.org/u/srajan76)
#### Post date: [July 29, 2020, 8:45pm UTC](https://discourse.julialang.org/t/unable-to-delete-constraints-stored-in-dictionaries-using-jump-constraint-macro/43920/1 "2020-07-29T20:45:12Z")
I am unable to delete the constraints which is created and stored in a dictionary using the JuMP.@constraint macro.
the constraints are added in the form
for i in array
d[i] = JuMP.@constraint(model, variable[i] == constant)
end
when i delete them using
for i in array
delete(model, d[i])
end
it doesnt seem to work. any Idea where i am going wrong or what can be done to fix it?
---
### Author:  [@odow](https://discourse.julialang.org/u/odow)
#### Post date: [July 29, 2020, 8:48pm UTC](https://discourse.julialang.org/t/unable-to-delete-constraints-stored-in-dictionaries-using-jump-constraint-macro/43920/2 "2020-07-29T20:48:48Z")
This is a known issue. Please read: [https://github.com/jump-dev/JuMP.jl/issues/1956](https://github.com/jump-dev/JuMP.jl/issues/1956)
---
### Author:  [@srajan76](https://discourse.julialang.org/u/srajan76)
#### Post date: [July 29, 2020, 8:54pm UTC](https://discourse.julialang.org/t/unable-to-delete-constraints-stored-in-dictionaries-using-jump-constraint-macro/43920/3 "2020-07-29T20:54:28Z")
So from what i gather there is no way to delete it… only modification is the option?
Or do i have to reformulate the whole problem each time before I solve it? I have an equality constraint on some variables which i want to remove , add a few different constraints and re run the optimization
---
### Author:  [@odow](https://discourse.julialang.org/u/odow)
#### Post date: [July 29, 2020, 9:46pm UTC](https://discourse.julialang.org/t/unable-to-delete-constraints-stored-in-dictionaries-using-jump-constraint-macro/43920/4 "2020-07-29T21:46:56Z")
Ah, I mis-read your question. This should work:
```nohighlight
julia> model = Model()
A JuMP Model
Feasibility problem with:
Variables: 0
Model mode: AUTOMATIC
CachingOptimizer state: NO_OPTIMIZER
Solver name: No optimizer attached.
julia> array = [1, 2, 3]
3-element Array{Int64,1}:
1
2
3
julia> constant = 1
1
julia> @variable(model, x[array])
1-dimensional DenseAxisArray{VariableRef,1,...} with index sets:
Dimension 1, [1, 2, 3]
And data, a 3-element Array{VariableRef,1}:
x[1]
x[2]
x[3]
julia> d = Dict()
Dict{Any,Any} with 0 entries
julia> for i in array
d[i] = @constraint(model, x[i] == constant)
end
julia> println(model)
Feasibility
Subject to
x[1] = 1.0
x[2] = 1.0
x[3] = 1.0
julia> for i in array
delete(model, d[i])
end
julia> println(model)
Feasibility
Subject to
```
---
### Author:  [@srajan76](https://discourse.julialang.org/u/srajan76)
#### Post date: [July 29, 2020, 11:18pm UTC](https://discourse.julialang.org/t/unable-to-delete-constraints-stored-in-dictionaries-using-jump-constraint-macro/43920/5 "2020-07-29T23:18:27Z")
Thats useful…Can you solve the given model-
julia\> println(model)
Feasibility
Subject to
x[1] = 1.0
x[2] = 1.0
x[3] = 1.0
write its solution and then delete the constraints? I for some reason am still unable to do so
Also i was using JuMP.@constraint is it different than using @constraint?
---
### Author:  [@odow](https://discourse.julialang.org/u/odow)
#### Post date: [July 30, 2020, 1:04am UTC](https://discourse.julialang.org/t/unable-to-delete-constraints-stored-in-dictionaries-using-jump-constraint-macro/43920/6 "2020-07-30T01:04:34Z")
Please show a minimal version of the code you are trying to run the demonstrates the error.
The first post of [Please read: make it easier to help you - #81](https://discourse.julialang.org/t/psa-make-it-easier-to-help-you/14757/81) has some good tips to read first.
---
### Author:  [@srajan76](https://discourse.julialang.org/u/srajan76)
#### Post date: [July 30, 2020, 1:15am UTC](https://discourse.julialang.org/t/unable-to-delete-constraints-stored-in-dictionaries-using-jump-constraint-macro/43920/7 "2020-07-30T01:15:18Z")
Ok.iwas actually thinking perhaps I should use a call back routine… given I an solving the problem then using the solution to add delete constraints and solving again iteratively… will post code shortly