如何分配给嵌套地图

Question

我有类似的东西

type rateLimit struct {

    Count    int

}

type RateLimiter struct {

    cachePeriod   time.Duration

    rateLimits map[string]*rateLimit

}

和这样的功能：

func NewRateLimiter(////) *RateLimiter {

    rateLimits := make(map[string]*rateLimit)

    return &RateLimiter{

        cachePeriod:   cachePeriod,

        rateLimits: rateLimits,

    }

}

此结构允许您创建嵌套结构，例如 rateLimits["foo"] = a

但我正在尝试进行更改以使其嵌套并且我可以做到rateLimits["foo"]["bar"] = a

我尝试将结构更改为 rateLimits := make(map[string]map[string]*rateLimit)

和

type rateLimiter struct {

    cachePeriod   time.Duration

    rateLimits map[string]map[string]*rateLimit

}

但我得到panic: assignment to entry in nil map [recovered] panic: assignment to entry in nil map

Answer 1

rateLimits := make(map[string]map[string]*rateLimit)rateLimits["foo"] = make(map[string]*rateLimit)rateLimits["foo"]["bar"] = arateLimits := map[string]map[string]*rateLimit{"foo": {"bar": a}}

Answer 2

您必须制作嵌套地图：func setNested(m1 map[string]map[string]string, k1, k2 string, v string) {    m2 := m1[k1]     if m2 == nil {       m2 = make(map[string]string)       m1[k1] = m2    }    m2[k2] = v}像这样使用它： setNested(rateLimits, "foo", "bar", a)