null-extended 
import "gopkg.in/nullbio/null.v5"
null-extended 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, json.Unmarshaler and sql.Scanner.
null package
import "gopkg.in/nullbio/null.v5"
null.JSON
Nullable []byte.
Will marshal to JSON null if Invalid. []byte{} input will not produce an Invalid JSON, but []byte(nil) will. This should be used for storing raw JSON in the database.
Also has null.JSON.Marshal and null.JSON.Unmarshal helpers to marshal and unmarshal foreign objects.
null.Bytes
Nullable []byte.
Will marshal to JSON null if Invalid. []]byte{} input will not produce an Invalid Bytes, but []byte(nil) will. This should be used for storing binary data (bytea in PSQL for example) in the database.
null.String
Nullable string.
Marshals to JSON null if SQL source data is null. Zero (blank) input will not produce a null String. Can unmarshal from sql.NullString JSON input or string input.
null.Bool
Nullable bool.
Marshals to JSON null if SQL source data is null. False input will not produce a null Bool. Can unmarshal from sql.NullBool JSON input.
null.Time
Marshals to JSON null if SQL source data is null. Uses time.Time's marshaler. Can unmarshal from pq.NullTime and similar JSON input.
null.Float32
Nullable float32.
Marshals to JSON null if SQL source data is null. Zero input will not produce a null Float32. Can unmarshal from null.NullFloat32 JSON input.
null.Float64
Nullable float64.
Marshals to JSON null if SQL source data is null. Zero input will not produce a null Float64. Can unmarshal from sql.NullFloat64 JSON input.
null.Int
Nullable int.
Marshals to JSON null if SQL source data is null. Zero input will not produce a null Int. Can unmarshal from null.NullInt JSON input.
null.Int8
Nullable int8.
Marshals to JSON null if SQL source data is null. Zero input will not produce a null Int8. Can unmarshal from null.NullInt8 JSON input.
null.Int16
Nullable int16.
Marshals to JSON null if SQL source data is null. Zero input will not produce a null Int16. Can unmarshal from null.NullInt16 JSON input.
null.Int32
Nullable int32.
Marshals to JSON null if SQL source data is null. Zero input will not produce a null Int32. Can unmarshal from null.NullInt32 JSON input.
null.Int64
Nullable int64.
Marshals to JSON null if SQL source data is null. Zero input will not produce a null Int64. Can unmarshal from sql.NullInt64 JSON input.
null.Uint
Nullable uint.
Marshals to JSON null if SQL source data is null. Zero input will not produce a null Uint. Can unmarshal from null.NullUint JSON input.
null.Uint8
Nullable uint8.
Marshals to JSON null if SQL source data is null. Zero input will not produce a null Uint8. Can unmarshal from null.NullUint8 JSON input.
null.Uint16
Nullable uint16.
Marshals to JSON null if SQL source data is null. Zero input will not produce a null Uint16. Can unmarshal from null.NullUint16 JSON input.
null.Uint32
Nullable int32.
Marshals to JSON null if SQL source data is null. Zero input will not produce a null Uint32. Can unmarshal from null.NullUint32 JSON input.
null.Int64
Nullable uint64.
Marshals to JSON null if SQL source data is null. Zero input will not produce a null Uint64. Can unmarshal from null.NullUint64 JSON input.
zero package
import "gopkg.in/nullbio/null.v5/zero"
zero.JSON
Nullable []byte.
Will marshal to JSON null if Invalid. []byte{} and []byte(nil) will produce an Invalid JSON. This should be used for storing raw JSON in the database.
Also has null.JSON.Marshal and null.JSON.Unmarshal helpers to marshal and unmarshal foreign objects.
zero.Bytes
Nullable []byte.
Will marshal to JSON null if Invalid. []byte{} and []byte(nil) will produce an Invalid Bytes. This should be used for storing binary data (bytea in PSQL for example) in the database.
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. Can unmarshal from sql.NullString JSON input.
zero.Bool
Nullable bool.
Will marshal to false if null. false produces a null Float. Null values and zero values are considered equivalent. Can unmarshal from sql.NullBool JSON input.
zero.Time
Will marshal to the zero time if null. Uses time.Time's marshaler. Can unmarshal from pq.NullTime and similar JSON input.
zero.Float32
Nullable float32.
Will marshal to 0 if null. 0.0 produces a null Float32. Null values and zero values are considered equivalent. Can unmarshal from zero.NullFloat32 JSON input.
zero.Float64
Nullable float64.
Will marshal to 0 if null. 0.0 produces a null Float64. Null values and zero values are considered equivalent. Can unmarshal from sql.NullFloat64 JSON input.
zero.Int
Nullable int.
Will marshal to 0 if null. 0 produces a null Int. Null values and zero values are considered equivalent. Can unmarshal from zero.NullInt JSON input.
zero.Int8
Nullable int8.
Will marshal to 0 if null. 0 produces a null Int8. Null values and zero values are considered equivalent. Can unmarshal from zero.NullInt8 JSON input.
zero.Int16
Nullable int16.
Will marshal to 0 if null. 0 produces a null Int16. Null values and zero values are considered equivalent. Can unmarshal from zero.NullInt16 JSON input.
zero.Int32
Nullable int32.
Will marshal to 0 if null. 0 produces a null Int32. Null values and zero values are considered equivalent. Can unmarshal from zero.NullInt32 JSON input.
zero.Int64
Nullable int64.
Will marshal to 0 if null. 0 produces a null Int64. Null values and zero values are considered equivalent. Can unmarshal from sql.NullInt64 JSON input.
zero.Uint
Nullable uint.
Will marshal to 0 if null. 0 produces a null Uint. Null values and zero values are considered equivalent. Can unmarshal from zero.NullUint JSON input.
zero.Uint8
Nullable uint8.
Will marshal to 0 if null. 0 produces a null Uint8. Null values and zero values are considered equivalent. Can unmarshal from zero.NullUint8 JSON input.
zero.Uint16
Nullable uint16.
Will marshal to 0 if null. 0 produces a null Uint16. Null values and zero values are considered equivalent. Can unmarshal from zero.NullUint16 JSON input.
zero.Uint32
Nullable uint32.
Will marshal to 0 if null. 0 produces a null Uint32. Null values and zero values are considered equivalent. Can unmarshal from zero.NullUint32 JSON input.
zero.Uint64
Nullable uint64.
Will marshal to 0 if null. 0 produces a null Uint64. Null values and zero values are considered equivalent. Can unmarshal from zero.NullUint64 JSON input.
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