How to Safely Convert interface{} to int in Go?

Converting interface{} to int in Go

When fetching data from JSON and attempting to cast it to an integer, you may encounter an error stating that you cannot convert an interface{} to an int. This error occurs due to Go's type-assertion rules.

In your code, you have the following line:

iAreaId := int(val)

This line attempts to convert the val, which has the type interface{}, to an int using a type cast. However, type casting an interface{} to an int is not allowed.

To resolve this issue, you need to use a type assertion instead:

iAreaId := val.(int)

A type assertion extracts the underlying value from the interface{} if it has the declared type. If the value does not have the declared type, the type assertion will panic.

Alternatively, you can use a non-panicking version of type assertion using a second return value:

iAreaId, ok := val.(int)

The ok variable will be true if the type assertion was successful and false if it was unsuccessful.

By using a type assertion correctly, you can successfully convert an interface{} to an int in Go.

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