How to solve golang error: non-interface type cannot be assigned to interface{}, solution

How to solve golang error: non-interface type cannot be assigned to interface{ }, solution

In the process of writing code in Golang, we sometimes encounter A common error message: non-interface type cannot be assigned to interface{ }. This error message may appear when the program attempts to assign a non-interface type to the interface{} type. So, how do we solve this problem? The solution is detailed below, with code examples.

First of all, we need to understand the concepts of interfaces and interface{} types in Golang. In Golang, an interface is a collection of one or more method signatures. The interface{} type represents an empty interface, that is, it can accept values ​​of any type. Since the interface{} type can accept values ​​of any type, type assertion is required when assigning values.

The following is a simple code example that shows the error non-interface type cannot be assigned to interface{ } when assigning and the corresponding solution:

package main

import (
    "fmt"
)

type Animal interface {
    Say() string
}

type Cat struct {
    Name string
}

func (c Cat) Say() string {
    return "Meow"
}

func main() {
    cat := Cat{Name: "Tom"}

    // 错误示例：尝试将非接口类型赋值给interface{}类型
    var animal interface{}
    animal = cat // 报错：non-interface type cannot be assigned to interface{}
    fmt.Println(animal)

    // 正确示例：使用类型断言将非接口类型赋值给interface{}类型
    animal = cat.(Animal)
    fmt.Println(animal.Say())
}

In the above example , we define an Animal interface and a Cat structure, and the Cat structure implements the Say method. In the main function, we create a Cat object and try to assign it to a variable of type interface{}. In the error example, we directly assign cat to animal, and an error message non-interface type cannot be assigned to interface{} will appear.

In order to solve this problem, we need to use type assertions to assign non-interface types to interface{} types. In the correct example, we use cat.(Animal) to convert cat to the Animal interface type and assign it to the animal variable. In this way, the non-interface type can be successfully assigned to the interface{} type.

To summarize, when the error non-interface type cannot be assigned to interface{} occurs in Golang, we need to use type assertions to convert the non-interface type to the interface type and then assign it. This way we can resolve the issue and continue programming and development as normal. I hope the solutions in this article can help you.

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