如何从地图中获取价值

问题描述：

从地图中获取数据

res = map[Event_dtmReleaseDate:2009-09-15 00:00:00 +0000 +00:00 Trans_strGuestList:<nil> strID:TSTB]

注意

如何从上述结果中获取以下值

Note

How to get the following value from the above result

1.Event_dtmReleaseDate

2.strID

3.Trans_strGuestList

我尝试过的事情:

res.Map("Event_dtmReleaseDate");

错误:res.Map未定义(类型map [string] interface {}没有字段或方法Map)

Error : res.Map undefined (type map[string]interface {} has no field or method Map)

res.Event_dtmReleaseDate;

错误:v.id未定义(类型map [string] interface {}没有字段或方法ID)

Error: v.id undefined (type map[string]interface {} has no field or method id)

答

您的变量是map[string]interface {}，表示键是字符串，但值可以是任何值.通常，访问此文件的方式是:

Your variable is a map[string]interface {} which means the key is a string but the value can be anything. In general the way to access this is:

mvVar := myMap[key].(VariableType)

或者在字符串值的情况下:

Or in the case of a string value:

id  := res["strID"].(string)

请注意，如果类型不正确或键在映射中不存在，这将会引起恐慌，但是我建议您阅读更多有关Go映射和类型断言的信息.

Note that this will panic if the type is not correct or the key does not exist in the map, but I suggest you read more about Go maps and type assertions.

在此处阅读有关地图的信息: http://golang.org/doc/effective_go.html#maps

Read about maps here: http://golang.org/doc/effective_go.html#maps

有关类型声明和接口转换的信息，请参见: http://golang.org/doc/effective_go.html#interface_conversions

And about type assertions and interface conversions here: http://golang.org/doc/effective_go.html#interface_conversions

没有恐慌的安全方法是这样的:

The safe way to do it without a chance to panic is something like this:

var id string
var ok bool
if x, found := res["strID"]; found {
     if id, ok = x.(string); !ok {
        //do whatever you want to handle errors - this means this wasn't a string
     }
} else {
   //handle error - the map didn't contain this key
}

注意

Note

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