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https://github.com/graphql-java/graphql-java-extended-scalars

A library of extended scalars for graphql-java
https://github.com/graphql-java/graphql-java-extended-scalars

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A library of extended scalars for graphql-java

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README 

        
# Extended Scalars for graphql-java



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## Overview



This library provides extended scalars for [graphql-java](https://github.com/graphql-java/graphql-java)



[GraphQL Scalars](https://spec.graphql.org/draft/#sec-Scalars) are the primitive leaf values in the GraphQL type system which cannot be queried further via sub-field selections.



The GraphQL Specification defines `String`, `Int`, `Float`, `Boolean` and `ID` as well-defined [built-in scalars](https://spec.graphql.org/draft/#sec-Scalars.Built-in-Scalars) that must be present in a graphql type

system. Beyond these, it is up to an implementation to decide what [custom scalars](https://spec.graphql.org/draft/#sec-Scalars.Custom-Scalars) are present.



You would use custom scalars when you want to describe more meaningful behavior or ranges of values.



# Getting started



## How to install



To use this library put the following into your gradle config



```java

implementation 'com.graphql-java:graphql-java-extended-scalars:22.0'

```



or the following into your Maven config



```xml



  com.graphql-java

  graphql-java-extended-scalars

  22.0



```



> Note:

>

> use 22.0 or above for graphql-java 22.x and above

> 

> use 21.0 for graphql-java 21.x

>

> use 20.2 for graphql-java 20.x

> 



## How to use extended scalars



### Direct use



Register the scalar with `graphql-java`



```java

RuntimeWiring.newRuntimeWiring().scalar(ExtendedScalars.DateTime)

```



### Spring for GraphQL



If you are using [Spring for GraphQL](https://docs.spring.io/spring-graphql/docs/current/reference/html/), register the scalar with `RuntimeWiringConfigurer`



```java

@Configuration

public class GraphQlConfig {

    @Bean

    public RuntimeWiringConfigurer runtimeWiringConfigurer() {

        return wiringBuilder -> wiringBuilder.scalar(ExtendedScalars.DateTime);

    }

}

```



### Netflix DGS



Note: Netflix also wraps this library in `com.netflix.graphql.dgs:graphql-dgs-extended-scalars` for [automatic registration](https://netflix.github.io/dgs/scalars/#automatically-register-scalar-extensions-via-graphql-dgs-extended-scalars).



If you are using [Netflix DGS](https://netflix.github.io/dgs), please see the following docs:

 - [registration through runtime wiring](https://netflix.github.io/dgs/scalars/#register-scalar-extensions-via-dgsruntimewiring)

 - [configuration documentation](https://netflix.github.io/dgs/configuration/#dgs-extended-scalars-graphql-dgs-extended-scalars)



## How to add extended scalars to your schema



The GraphQL Specification recommends the use of the [@specifiedBy](https://spec.graphql.org/October2021/#sec--specifiedBy) built-in schema directive to provide a scalar specification URL for specifying the behavior of custom scalar types.



```graphql

directive @specifiedBy(url: String!) on SCALAR

```



To use a extended scalar in your schema, define the scalar like shown below for `DateTime`



```graphql

scalar DateTime

  @specifiedBy(url: "https://scalars.graphql.org/andimarek/date-time.html")



type Something {

  someDateTime: DateTime

}

```



# Custom Scalars



## Alias Scalars



Scalar Definition

Description




scalar AliasedScalar



You can create aliases for existing scalars to add more semantic meaning to them.



For example a link to a social media post could be representing by a `String` but the name `SocialMediaLink` is a

more semantically meaningful name for that scalar type.



For example, you would build it like this:



```java

AliasedScalar socialMediaLink = ExtendedScalars.newAliasedScalar("SocialMediaLink")

        .aliasedScalar(Scalars.GraphQLString)

        .build()

```



And use it in a SDL schema like this :



```graphql

type Customer {

  name: String

  socialMediaLink: SocialMediaLink

}

```



## Date & Time Scalars



Scalar Definition

Description




scalar DateTime

  @specifiedBy(url: 

    "https://scalars.graphql.org/andimarek/date-time.html"

  )



A RFC-3339 compliant date time scalar that accepts string values like 1996-12-19T16:39:57-08:00 and produces java.time.OffsetDateTime objects at runtime.




scalar Date

  @specifiedBy(url: 

    "https://tools.ietf.org/html/rfc3339"

  )


A RFC-3339 compliant date scalar that accepts string values like 1996-12-19 and produces java.time.LocalDate objects at runtime.




scalar Time

  @specifiedBy(url: 

    "https://tools.ietf.org/html/rfc3339"

  )



A RFC-3339 compliant time scalar that accepts string values like 16:39:57-08:00 and produces java.time.OffsetTime objects at runtime.




scalar LocalTime



24-hour clock time string in the format hh:mm:ss.sss or hh:mm:ss if partial seconds is zero and produces java.time.LocalTime objects at runtime.



An example declaration in SDL might be:



```graphql

type Customer {

  birthDay: Date

  workStartTime: Time

  bornAt: DateTime

}



type Query {

  customers(bornAfter: DateTime): [Customers]

}

```



And example query might look like:



```graphql

query {

  customers(bornAfter: "1996-12-19T16:39:57-08:00") {

    birthDay

    bornAt

  }

}

```



## ID Scalars



Scalar Definition

Description




scalar UUID

  @specifiedBy(url: 

    "https://tools.ietf.org/html/rfc4122"

  )



A universally unique identifier scalar that accepts uuid values like 2423f0a0-3b81-4115-a189-18df8b35e8fc and produces java.util.UUID instances at runtime.



## Numeric Scalars



Scalar Definition

Description



scalar PositiveInt


An Int scalar that MUST be greater than zero.



scalar NegativeInt


An Int scalar that MUST be less than zero.



scalar NonPositiveInt


An Int scalar that MUST be less than or equal to zero.



scalar NonNegativeInt


An Int scalar that MUST be greater than or equal to zero.



scalar PositiveFloat


An Float scalar that MUST be greater than zero.



scalar NegativeFloat


An Float scalar that MUST be less than zero.



scalar NonPositiveFloat


An Float scalar that MUST be less than or equal to zero.



scalar NonNegativeFloat


An Float scalar that MUST be greater than or equal to zero.



The numeric scalars are derivations of the standard GraphQL `Int` and `Float` scalars that enforce range limits.



An example declaration in SDL might be:



```graphql

type Customer {

  name: String

  currentHeight: PositiveInt

  weightLossGoal: NonPositiveInt

  averageWeightLoss: NegativeFloat

}



type Query {

  customers(height: PositiveInt): [Customers]

}

```



And example query might look like:



```graphql

query {

  customers(height: 182) {

    name

    height

    weightLossGoal

  }

}

```



## Java Primitives



Scalar Definition

Description



scalar GraphQLLong


A scalar which represents java.lang.Long



scalar GraphQLShort


A scalar which represents java.lang.Short



scalar GraphQLByte


A scalar which represents java.lang.Byte



scalar GraphQLBigDecimal


A scalar which represents java.math.BigDecimal



scalar GraphQLBigInteger


A scalar which represents java.math.BigInteger



scalar GraphQLChar


A scalar which represents java.lang.Character



## Locale Scalar



Scalar Definition

Description




scalar Locale

  @specifiedBy(url: 

    "https://tools.ietf.org/html/bcp47"

  )



The Locale scalar handles IETF BCP 47 language tags via the JDK method Locale.forLanguageTag.



```graphql

type Customer {

  name: String

  locale: Locale

}



type Query {

  customers(inLocale: Locale): [Customers]

}

```



An example query to look for customers in the Romanian locale might look like:



```graphql

query {

  customers(inLocale: "ro-RO") {

    name

    locale

  }

}

```



## Country Code Scalar



Scalar Definition

Description




scalar CountryCode 

  @specifiedBy(url: 

    "https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2"

  )



The CountryCode scalar type as defined by ISO 3166-1 alpha-2.



An example declaration in SDL might be:



```graphql

scalar CountryCode



type Customer {

  name: String

  countryCode: CountryCode

}

```



And example query might look like:



```graphql

query {

  customers(code: "US") {

    name

    countryCode

  }

}

```



## Currency Scalar



Scalar Definition

Description




scalar Currency

  @specifiedBy(url: 

    "https://en.wikipedia.org/wiki/ISO_4217"

  )



A field whose value is an ISO-4217 currency.



An example declaration in SDL might be:



```graphql

scalar Currency



type Account {

  id: String

  currency: Currency

  accountNumber: String

}

```



And example query might look like:



```graphql

query {

  accounts(currency: "USD") {

    id

    currency

    accountNumber

  }

}

```



## URL Scalars



Scalar Definition

Description




scalar URL

  @specifiedBy(url: 

    "https://www.w3.org/Addressing/URL/url-spec.txt"

  )



An url scalar that accepts string values like https://www.w3.org/Addressing/URL/url-spec.txt and produces java.net.URL objects at runtime.



## Object / JSON Scalars



Scalar Definition

Description



scalar Object


An object scalar that accepts any object as a scalar value.



scalar JSON


A synonym for the Object scalar, it will accept any object as a scalar value.



One of the design goals of GraphQL, is that the type system describes the shape of the data returned.



The `Object` / `JSON` scalars work against this some what because they can return compound values outside the type system. As such

they should be used sparingly. In general your should aim to describe the data via the GraphQL type system where you can and only

resort to the `Object` / `JSON` scalars in very rare circumstances.



An example might be an extensible GraphQL system where systems can input custom metadata objects that cant be known at

schema type design time.



An example declaration in SDL might be:



```graphql

type Customer {

  name: String

  associatedMetaData: JSON

}



type Query {

  customers(filterSyntax: JSON): [Customers]

}

```



And example query might look like:



```graphql

query {

  customers(

    filterSyntax: {

      startSpan: "First"

      matchCriteria: { countryCode: "AU", isoCodes: ["27B-34R", "95A-E23"] }

    }

  ) {

    name

    associatedMetaData

  }

}

```



Note : The `JSON` scalar is a simple alias type to the `Object` scalar because often the returned data is a blob of JSON. They are

all just objects at runtime in `graphql-java` terms and what network serialization protocol is up to you. Choose whichever name you think

adds more semantic readers to your schema consumers.



## Regex Scalars



Scalar Name

Description



RegexScalar

Allows you to build a new scalar via a builder pattern using regular expressions.



The RegexScalar has a builder where you provide one or more regex patterns that control the acceptable values

for a new scalar.



You name the scalar and it provides an implementation.



For example, imagine a `phoneNumber` scalar like this :



```java



    RegexScalar phoneNumberScalar = ExtendedScalars.newRegexScalar("phoneNumber")

            .addPattern(Pattern.compile("\\([0-9]*\\)[0-9]*"))

            .build()



```