如何知道Golang中是否填充了空的struct var？ [重复]

Question

This question already has an answer here:

• How check if a property was set in a struct 3 answers
• How to recognize void value and unspecified field when unmarshaling in Go? 1 answer
• How to check if a specific property of a struct is null? 1 answer

In Python I can do something like this:

aModel = None
models = somefunction()
for model in models:
    if model.cool is False and model.somenumber > -5:
        aModel = model
        break

if aModel:
    print("We found a model we like!!")

I'm trying to do the same thing in Golang. After initialization, a variable of some struct already IS a struct and already HAS values though (such as false for a bool var, and 0 for an int var).

So considering the following code:

type SomeModel struct {
    cool bool
    somenumber int
}

func main() {

    somemodels = somefunction()

    var aModel SomeModel
    for _, v := range somemodels {
        fmt.Println(v)
        if (v.cool == false && v.somenumber > -5) {
            aModel = v
        }
    }
    fmt.Println(aModel)
}

If this prints out {false 0}, how can I know whether this is a model I found in the slice, or if it's the default model I set before the loop?

I can of course set another variable like foundamodel := false and set that to true if I found something, but that doesn't really seem like the obvious way to go.

Or is it in Go?

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Answer 1

You can use a pointer instead of a concrete value:

var aModel *SomeModel
for _, v := range somemodels {
    fmt.Println(v)
    if v.cool == false && v.somenumber > -5 {
        aModel = &v
        break
    }
}
if aModel != nil {
    fmt.Println(*aModel)
}