Model Storage
Unlike the policy, the model can be loaded only, it cannot be saved. Because we think the model is not a dynamic component and should not be modified at run-time, so we don't implement an API to save the model into a storage.
However, the good news is, we provide several ways to load a model either statically or dynamically:
Load model from .CONF file
This is the most common way to use Casbin. It's easy to understand for beginners and convenient for sharing when you ask Casbin team for help.
```go
e := casbin.NewEnforcer("examples/basic_model.conf", "examples/basic_policy.csv")
```
Load model from code
The model can be initialized dynamically from code instead of using .CONF file. Here's an example for the RBAC model:
// Initialize the model from Go code.
m := casbin.NewModel()
m.AddDef("r", "r", "sub, obj, act")
m.AddDef("p", "p", "sub, obj, act")
m.AddDef("g", "g", "_, _")
m.AddDef("e", "e", "some(where (p.eft == allow))")
m.AddDef("m", "m", "g(r.sub, p.sub) && r.obj == p.obj && r.act == p.act")
// Load the policy rules from the .CSV file adapter.
// Replace it with your adapter to avoid files.
a := persist.NewFileAdapter("examples/rbac_policy.csv")
// Create the enforcer.
e := casbin.NewEnforcer(m, a)
Load model from string
Or you can just get the model from a single multi-line string:
// Initialize the model from a string.
text :=
`
[request_definition]
r = sub, obj, act
[policy_definition]
p = sub, obj, act
[role_definition]
g = _, _
[policy_effect]
e = some(where (p.eft == allow))
[matchers]
m = g(r.sub, p.sub) && r.obj == p.obj && r.act == p.act
`
m := NewModel(text)
// Load the policy rules from the .CSV file adapter.
// Replace it with your adapter to avoid files.
a := persist.NewFileAdapter("examples/rbac_policy.csv")
// Create the enforcer.
e := casbin.NewEnforcer(m, a)
The above two ways are equivalent with the following common use:
[request_definition]
r = sub, obj, act
[policy_definition]
p = sub, obj, act
[role_definition]
g = _, _
[policy_effect]
e = some(where (p.eft == allow))
[matchers]
m = g(r.sub, p.sub) && r.obj == p.obj && r.act == p.act
e := casbin.NewEnforcer("examples/rbac_model.conf", "examples/rbac_policy.csv")