英文:
golang: How to assign a new map to a struct field
问题
我正在迭代一个包含map字段的结构体数组：
type Config struct {
// ... 其他字段
KV map[string]interface{} `json:"kv"`
}
在一个测试文件中，我知道KV是空的，所以我正在迭代Config对象的数组，并给它赋予一个新的map：
for _, v := range wrapper.Configs { // 我知道这个数组的长度大于0
newMap := map[string]interface{}{
"key1": "val1",
"key2": "val2",
"key3": "val3",
}
v.KV = newMap // 我先尝试直接赋值，不起作用，然后尝试复制，也不起作用
}
for _, v := range wrapper.Configs {
fmt.Println(v.KV)
}
但是循环结束后，KV始终为空。
我还尝试过：
for _, v := range wrapper.Configs { // 我知道这个数组的长度大于0
v.KV = make(map[string]interface{})
newMap := map[string]interface{}{
"key1": "val1",
"key2": "val2",
"key3": "val3",
}
for kk, vv := range newMap {
v.KV[kk] = vv
}
}
我还没有找到正确且高效的方法来实现这个，我已经搜索了很多，但是我的搜索词给出了无关的结果。
英文:
I am iterating an array of structs which have a map field:
type Config struct {
// ... some other fields
KV map[string]interface{} `json:"kv"`
}
In a test file, I know KV is empty, so I am iterating the array of Config objects and assigning it a new map:
for _, v := range wrapper.Configs { // I know this is length > 0
newMap := map[string]interface{}{
"key1": "val1",
"key2": "val2",
"key3": "val3",
}
v.KV = newMap // I have first tried directly assigning. Didn't work, tried copy - didn't work either
}
for _, v := range wrapper.Configs {
fmt.Println(v.KV)
}
But after the loop, KV is always empty.
I also tried:
for _, v := range wrapper.Configs { // I know this is length > 0
v.KV = make(map[string]interface{})
newMap := map[string]interface{}{
"key1": "val1",
"key2": "val2",
"key3": "val3",
}
for kk, vv := range newMap {
v.KV[kk] = vv
}
I haven't been able to identify how to do this correctly, and also, efficiently.
Searched quite a bit but my search terms gave me unrelated results.
答案1
得分: 3
假设wrapper.Configs是一个结构体切片（而不是结构体指针切片），v是切片中项目的副本，因此更新操作不会改变原始数据。
要使这段代码正常工作，你可以这样写：
for i := range wrapper.Configs {
v := &wrapper.Configs[i]
...
}
英文:
Assuming wrapper.Configs is a slice of structs (rather than a slice of pointers to structs), v is a copy of the item in your slice, so updates don't change the originals.
To get this code to work, you can write:
for i := range wrapper.Configs {
v := &wrapper.Configs[i]
...
}
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