In this article, we will see how to create a custom type which is a map of structs in Go by using the inbuilt types such as struct and map types.

Define the struct

Design the struct named Employee that contains three members i.e. Name, Age, and Email as shown below.

type Employee struct {
    Name  string
    Age   int
    Email string
}

Create and initialize the map

Next, initialize the map using the make function, specifying the key and value types. In the below example, the key type can be any hashable type, such as string or int, and the value type is the struct which we have defined above.

The below map uses the employee ID as a key which is of type int and the employee data as an Employee type

people := make(map[int]Employee)

Add data to map

Add the data to the map as shown below. Simply assign a new struct instance to a specific key in the map to add the data to map.

people[1001] = Employee{Name: "John Doe", Age: 25, Email: "[email protected]"}
people[1002] = Employee{Name: "Jane Smith", Age: 30, Email: "[email protected]"}

Accessing the data from Map of struct

You can access the individual employee data using the map key i.e. the employee ID. You can also iterate over the structure as shown below.

john := people["john"]
john.Age = 26
people["john"] = john

/* Iterate over the struct */
for key, value := range people {
    fmt.Println(key, value)
}

Here is the complete example:

package main

import "fmt"

type Person struct {
	Name  string
	Age   int
	Email string
}

func main() {
	people := make(map[string]Person)

	people["john"] = Person{Name: "John Doe", Age: 25, Email: "[email protected]"}
	people["jane"] = Person{Name: "Jane Smith", Age: 30, Email: "[email protected]"}

	john := people["john"]
	john.Age = 26
	people["john"] = john

	for key, value := range people {
		fmt.Println("Key:", key)
		fmt.Println("Value:", value)
		fmt.Println("------")
	}
}

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