task_037_json_marshall

JSON Marshall

Explaination

This program demonstrates the encoding of Go data structures into JSON format. Let's go step-by-step:

1. Imports:

   • The program imports the fmt package for formatted I/O operations.
   • The encoding/json package is imported to use the JSON encoding and decoding functionalities.

2. Struct Definition:

   type person struct {
       First string
       Last  string
       Age   int
   }

   • A new person type is defined as a struct with three fields: First, Last, and Age.

3. Main Function:

   p1 := person {
       First: "James",
       Last: "Bond",
       Age: 23,
   }
   
   p2 := person {
       First: "Shinshan",
       Last: "Kazama",
       Age: 5,
   }

   • Two instances of the person struct, p1 and p2, are created with different values.

   sliceOfPeople := []person {
       p1,
       p2,
   }

   • A slice of person named sliceOfPeople is created, containing both p1 and p2.

   fmt.Println(sliceOfPeople)

   • The slice sliceOfPeople is printed, which will show the two person structs in a slice format.

   bs, err := json.Marshal(sliceOfPeople)

   • The json.Marshal function is called with the sliceOfPeople slice. This function attempts to convert the slice into its JSON representation. If successful, the resulting JSON byte slice is stored in bs, and err will be nil. If there's an error during the process, the err variable will capture that error.

   if err != nil {
       fmt.Println(err)
   }

   • If an error occurs during the JSON marshalling process, it will be printed.

   fmt.Println(string(bs))

   • The resulting JSON byte slice bs is converted to a string and printed. This will show the JSON representation of the sliceOfPeople slice.

Key Takeaway: The program demonstrates how to convert a slice of structs into its corresponding JSON representation in Go. It's important to note that the field names of the struct (First, Last, and Age) are capitalized, ensuring they're exported and can be accessed by the json.Marshal function. If they were not capitalized, they would not be included in the JSON output.

Output

• Run the following command

$ go run main.go
[{James Bond 23} {Shinshan Kazama 5}]
[{"First":"James","Last":"Bond","Age":23},{"First":"Shinshan","Last":"Kazama","Age":5}]