Universal function to convert Map to List in GO

php editor Strawberry introduces to you a practical tool called "General function to convert Map to List in GO". This function can help you convert the key-value map (Map) data structure into a list (List) data structure. Through this general function, you can easily convert complex data structures into a more concise form, improving the readability and maintainability of your code. Whether you have encountered similar needs in development or want to know more techniques about data structure conversion, this universal function will bring convenience and inspiration to you. Let’s explore this useful tool together!

Question content

How to write a function in go that converts any map to a list of objects (removing keys)?

For example:

func maptolist(inputmap map[any]any) any {
    var resultlist []any 
    for _, obj := range inputmap {
        resultlist = append(resultlist, obj)
    }
    return resultlist
}

func main() {
    mymap := make(map[string]string)
    mymap["a"] = "1"
    mymap["b"] = "12"
    l := maptolist(mymap).([]string)
    fmt.printf("(%v, %t)\n", l, l)
}

will output: ([1 12], []string)

But I always have type issues and haven't found a solution. I had a similar problem using type assertions or conversions.

cannot use myMap (variable of type map[string]string) as map[any]any value in argument to mapToList

How should I write the maptolist() function?

It must be taken as input inputmap map[any]any or inputmap any because I want to pass any type of map (map[string]customstruct; map[int][]customstruct wait)

Update: I added the function and more details about the inputs when I first wrote it

Workaround

See this article about generics Tutorial or Language Specification

any is not a variable type, it is a type constraint, a description of the type that can be used. You need to define the type parameters using the constraint any and then reference the generic type from the parameter signature.

//                                 | from this point on, k and v are
//                                 | now valid types to use in the function
func maptoslice[k comparable, v any](m map[k]v) []v {
    s := make([]v, 0, len(m))
    for _, v := range m {
        s = append(s, v)
    }
    return s
}

Parameter m must be map[k]v, where k is the comparable type, v Is any type. The return type []v will be a slice of the same type as the value in the input map.

Note that any cannot be used as a constraint on a map key, since not all types can be used as keys, only comparable types.

Then, to call the method, pass in a type that satisfies the constraint (e.g. map[string][]string), optionally displaying the type parameter explicitly.

m := map[string][]string{
    "a": {"b", "c"},
    "d": {"e", "f"},
}
s := maptoslice(m)
// or
t := maptoslice[string, []string](m)
// [[b c] [e f]]

By being explicit about types, you can document your code yourself and catch any unexpected type issues. For example, the following code will return an error:

v := mapToSlice[string, []int](m)
...
./main.go:14:33: cannot use m (variable of type map[string][]string) as map[string][]int value in argument to mapToSlice[string, []int]

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