How Can Golang's Dynamic Struct Type Return Improve Code Efficiency While Managing Type Safety Risks?

Dynamic Struct Type Return in Golang

In Revel projects, there can often be significant redundancy in return types across different models.

Consider these two functions:

func (c Helper) Brands() []*models.Brand {
    // Select from rethinkdb and populate models.Brand
    var brands []*models.Brand
    rows.All(&brands)
    return brands
}

func (c Helper) BlogPosts() []*models.Post {
    // Select from rethinkdb and populate models.Post
    var posts []*models.Post
    rows.All(&posts)
    return posts
}

Both functions return the same type of data (pointers to slices of structs). To reduce redundancy, one idea is to create a generic return function that returns an interface{} capable of representing different types.

func (c Helper) ReturnModels(modelName string) interface{} {
    // Select from rethinkdb based on modelName and return interface{}
}

With this approach, there would be only one return function, simplifying code and reducing redundancy.

However, it's important to note that returning interface{} comes with caveats:

1. Loss of type information: The compiler will no longer be able to enforce type safety, so casting will be necessary before using the returned value safely.
2. Type switches and assertions: Casting will require using type switches or assertions, which can lead to additional complexity and potential errors.

The following code example demonstrates this approach:

package main

import "fmt"

type Post struct {
    Author  string
    Content string
}

type Brand struct {
    Name string
}

var database map[string]interface{}

func init() {
    database = make(map[string]interface{})

    brands := []Brand{
        {Name: "Gucci"},
        {Name: "LV"},
    }
    database["brands"] = brands

    posts := []Post{
        {Author: "J.K.R", Content: "Whatever"},
    }
    database["posts"] = posts
}

func main() {
    fmt.Println("List of Brands:")
    if brands, ok := ReturnModels("brands").([]Brand); ok {
        fmt.Printf("%v", brands)
    }

    fmt.Println("\nList of Posts:")
    if posts, ok := ReturnModels("posts").([]Post); ok {
        fmt.Printf("%v", posts)
    }
}

func ReturnModels(modelName string) interface{} {
    return database[modelName]
}

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