How to search for an element in a golang slice

Question

I have a slice of structs.

type Config struct {     Key string     Value string }  // I form a slice of the above struct var myconfig []Config   // unmarshal a response body into the above slice if err := json.Unmarshal(respbody, &myconfig); err != nil {     panic(err) }  fmt.Println(config) 

Here is the output of this:

[{key1 test} {web/key1 test2}] 

How can I search this array to get the element where key="key1"?

Answer 1

With a simple for loop:

for _, v := range myconfig {     if v.Key == "key1" {         // Found!     } } 

Note that since element type of the slice is a struct (not a pointer), this may be inefficient if the struct type is "big" as the loop will copy each visited element into the loop variable.

It would be faster to use a range loop just on the index, this avoids copying the elements:

for i := range myconfig {     if myconfig[i].Key == "key1" {         // Found!     } } 

Notes:

It depends on your case whether multiple configs may exist with the same key, but if not, you should break out of the loop if a match is found (to avoid searching for others).

for i := range myconfig {     if myconfig[i].Key == "key1" {         // Found!         break     } } 

Also if this is a frequent operation, you should consider building a map from it which you can simply index, e.g.

// Build a config map: confMap := map[string]string{} for _, v := range myconfig {     confMap[v.Key] = v.Value }  // And then to find values by key: if v, ok := confMap["key1"]; ok {     // Found }