null 
import "gopkg.in/guregu/null.v4"
null is a library with reasonable options for dealing with nullable SQL and JSON values
There are two packages: null and its subpackage zero.
Types in null will only be considered null on null input, and will JSON encode to null. If you need zero and null be considered separate values, use these.
Types in zero are treated like zero values in Go: blank string input will produce a null zero.String, and null Strings will JSON encode to "". Zero values of these types will be considered null to SQL. If you need zero and null treated the same, use these.
All types implement sql.Scanner and driver.Valuer, so you can use this library in place of sql.NullXXX.
All types also implement: encoding.TextMarshaler, encoding.TextUnmarshaler, json.Marshaler, and json.Unmarshaler. A null object's MarshalText will return a blank string.
null package
import "gopkg.in/guregu/null.v4"
null.String
Nullable string.
Marshals to JSON null if SQL source data is null. Zero (blank) input will not produce a null String.
null.Int
Nullable int64.
Marshals to JSON null if SQL source data is null. Zero input will not produce a null Int.
null.Float
Nullable float64.
Marshals to JSON null if SQL source data is null. Zero input will not produce a null Float.
null.Bool
Nullable bool.
Marshals to JSON null if SQL source data is null. False input will not produce a null Bool.
null.Time
Marshals to JSON null if SQL source data is null. Zero input will not produce a null Time.
zero package
import "gopkg.in/guregu/null.v4/zero"
zero.String
Nullable string.
Will marshal to a blank string if null. Blank string input produces a null String. Null values and zero values are considered equivalent.
zero.Int
Nullable int64.
Will marshal to 0 if null. 0 produces a null Int. Null values and zero values are considered equivalent.
zero.Float
Nullable float64.
Will marshal to 0.0 if null. 0.0 produces a null Float. Null values and zero values are considered equivalent.
zero.Bool
Nullable bool.
Will marshal to false if null. false produces a null Float. Null values and zero values are considered equivalent.
zero.Time
Will marshal to the zero time if null. Uses time.Time's marshaler.
Can you add support for other types?
This package is intentionally limited in scope. It will only support the types that driver.Value supports. Feel free to fork this and add more types if you want.
Can you add a feature that ____?
This package isn't intended to be a catch-all data-wrangling package. It is essentially finished. If you have an idea for a new feature, feel free to open an issue to talk about it or fork this package, but don't expect this to do everything.
Package history
As of v4, unmarshaling from JSON sql.NullXXX JSON objects (ex. {"Int64": 123, "Valid": true}) is no longer supported. It's unlikely many people used this, but if you need it, use v3.
Bugs
json's ",omitempty" struct tag does not work correctly right now. It will never omit a null or empty String. This might be fixed eventually.
License
BSD