About go language loading json may encounter a pit

  • 2020-06-03 06:54:02
  • OfStack

It is

Go language is a simple but contains the meaning of language, everyone know go language summary in the standard library with built-in to json file processing, very convenient, when writing an application recently, need to load the configuration from json file, since it is go novice, ignore a detail, lead to load the content is empty all the time, the following few words said, need friends 1 up to look at the details:

Code demo

Code is the best vehicle for explanation

package config

type config struct{
 a string `json:"a"`
 b string `json:"a"`
func Load(file string)(*config, error){
 c = &config{}
 file, err := os.Open(file)
 if err != nil {
 //file open failed todo 
 jsonParser := json.NewDecoder(file)
 err = jsonParser.Decode(c)
 //c  What is the value of theta 


If you look at the code above, do you think that c was assigned successfully?

In fact, no, the json file parsed successfully but ultimately failed to assign

The reason is simple:

go variable function method access in different packages, the difference between access rights is whether the variable function method is capitalized if it is capitalized, it can be accessed in other packages

In this case, the json package and config are not the same package, access failed and set cannot be accessed

a b must be written in uppercase to be assigned


The reason why filed in config is set to lower case is to do access control, if you stick to lower case, how to assign value to field of config? Know friends can leave a message to share oh ~

Related articles: