**Model Storage**

Casbin 中的 Model 是仅加载（load-only）的：它们定义您的访问控制逻辑，并在运行时被视为静态数据。没有 API 用于在存储中保存或更新 Model。

您可以通过三种方式加载 Model：

从 CONF 文件加载

从 .conf 文件加载是常见做法，便于共享和讨论模型。

示例：examples/rbac_model.conf

[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

在创建 enforcer 时使用它：

e := casbin.NewEnforcer("examples/rbac_model.conf", "examples/rbac_policy.csv")

从代码加载

您可以在代码中构建模型，而不是使用文件：

import (
    "github.com/casbin/casbin/v3"
    "github.com/casbin/casbin/v3/model"
    "github.com/casbin/casbin/v3/persist/file-adapter"
)

// Build the model in Go.
m := model.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 using files.
a := fileadapter.NewAdapter("examples/rbac_policy.csv")

// Create the enforcer.
e := casbin.NewEnforcer(m, a)

从字符串加载

您也可以从字符串加载模型（例如从配置或数据库中）：

import (
    "github.com/casbin/casbin/v3"
    "github.com/casbin/casbin/v3/model"
)

// Model text (e.g. from config).
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, _ := model.NewModelFromString(text)

// Load the policy rules from the .CSV file adapter.
// Replace it with your adapter to avoid using files.
a := fileadapter.NewAdapter("examples/rbac_policy.csv")

// Create the enforcer.
e := casbin.NewEnforcer(m, a)