Assigning Default Values for Nil Environment Variables in Go
In Go, unlike Python's os.getenv() function, there is no built-in mechanism to assign a default value if an environment variable is not set. To address this issue, the following approaches can be employed:
Option 1: Using an if-else Block
Although relying on if-else statements to check variable states is generally discouraged, it can be used to assign default values for environment variables:
var mongoPassword string
if mongoPass := os.Getenv("MONGO_PASS"); mongoPass != "" {
mongoPassword = mongoPass
} else {
mongoPassword = "pass"
}Option 2: Creating a Helper Function
For multiple environment variables, creating a helper function provides a cleaner approach:
func getenv(key, fallback string) string {
value := os.Getenv(key)
if len(value) == 0 {
return fallback
}
return value
}To use it:
mongoPassword := getenv("MONGO_PASS", "pass")Option 3: Using os.LookupEnv(key) Boolean
os.LookupEnv returns two values: the value and its existence status. This can be used to set a default value as follows:
func getEnv(key, fallback string) string {
if value, ok := os.LookupEnv(key); ok {
return value
}
return fallback
}Note that if the environment variable's value is empty, the fallback value will be assigned instead.
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