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https://github.com/guregu/null

reasonable handling of nullable values
https://github.com/guregu/null

go json sql

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reasonable handling of nullable values

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## null [![GoDoc](https://godoc.org/github.com/guregu/null/v5?status.svg)](https://godoc.org/github.com/guregu/null/v5)

`import "github.com/guregu/null/v5"`



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.



#### Interfaces



- All types implement `sql.Scanner` and `driver.Valuer`, so you can use this library in place of `sql.NullXXX`.

- All types also implement `json.Marshaler` and `json.Unmarshaler`, so you can marshal them to their native JSON representation.

- All non-generic types implement `encoding.TextMarshaler`, `encoding.TextUnmarshaler`. A null object's `MarshalText` will return a blank string.



## null package



`import "github.com/guregu/null/v5"`



#### 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, null.Int32, null.Int16, null.Byte

Nullable int64/int32/int16/byte. 



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.



#### null.Value

Generic nullable value.



Will marshal to JSON null if SQL source data is null. Does not implement `encoding.TextMarshaler`.



## zero package



`import "github.com/guregu/null/v5/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, zero.Int32, zero.Int16, zero.Byte

Nullable int64/int32/int16/byte. 



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

Nullable time.



Will marshal to the zero time if null. Uses `time.Time`'s marshaler.



#### zero.Value[`T`]

Generic nullable value.



Will marshal to zero value if null. `T` is required to be a comparable type. Does not implement `encoding.TextMarshaler`.



## About



### Q&A



#### Can you add support for other types?

This package is intentionally limited in scope. It will only support the types that [`driver.Value`](https://godoc.org/database/sql/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



#### v5

- Now a Go module under the path `github.com/guregu/null/v5`

- Added missing types from `database/sql`: `Int32, Int16, Byte`

- Added generic `Value[T]` embedding `sql.Null[T]`



#### v4

- Available at `gopkg.in/guregu/null.v4`

- Unmarshaling from JSON `sql.NullXXX` JSON objects (e.g. `{"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](https://github.com/golang/go/issues/11939).



### License

BSD