Graphql id type

Graphql id type DEFAULT

Global Object Identification

Consistent object access enables simple caching and object lookups

To provide options for GraphQL clients to elegantly handle caching and data refetching, GraphQL servers need to expose object identifiers in a standardized way.

For this to work, a client will need to query via a standard mechanism to request an object by ID. Then, in the response, the schema will need to provide a standard way of providing these IDs.

Because little is known about the object other than its ID, we call these objects "nodes." Here is an example query for a node:

{

node(id:"4"){

id

...on User {

name

}

}

  • The GraphQL schema is formatted to allow fetching any object via the field on the root query object. This returns objects which conform to a "Node" interface.
  • The field can be extracted out of the response safely, and can be stored for re-use via caching and refetching.
  • Clients can use interface fragments to extract additional information specific to the type which conform to the node interface. In this case a "User".

The Node interface looks like:

interface Node {

id: ID!

}

With a User conforming via:

type User implements Node {

id: ID!

name: String!

}

Everything below describes with more formal requirements a specification around object identification in order to conform to ensure consistency across server implementations. These specifications are based on how a server can be compliant with the Relay API client, but can be useful for any client.

A GraphQL server compatible with this spec must reserve certain types and type names to support the consistent object identification model. In particular, this spec creates guidelines for the following types:

  • An interface named .
  • The field on the root query type.

The server must provide an interface called . That interface must include exactly one field, called that returns a non-null .

This should be a globally unique identifier for this object, and given just this , the server should be able to refetch the object.

Introspection#

A server that correctly implements the above interface will accept the following introspection query, and return the provided response:

{

__type(name:"Node"){

name

kind

fields {

name

type{

kind

ofType {

name

kind

}

}

}

}

}

yields

{

"__type":{

"name":"Node",

"kind":"INTERFACE",

"fields":[

{

"name":"id",

"type":{

"kind":"NON_NULL",

"ofType":{

"name":"ID",

"kind":"SCALAR"

}

}

}

]

}

}

The server must provide a root field called that returns the interface. This root field must take exactly one argument, a non-null ID named .

If a query returns an object that implements , then this root field should refetch the identical object when value returned by the server in the 's field is passed as the parameter to the root field.

The server must make a best effort to fetch this data, but it may not always be possible; for example, the server may return a with a valid , but when the request is made to refetch that user with the root field, the user's database may be unavailable, or the user may have deleted their account. In this case, the result of querying this field should be .

Introspection#

A server that correctly implements the above requirement will accept the following introspection query, and return a response that contains the provided response.

{

__schema {

queryType {

fields {

name

type{

name

kind

}

args {

name

type{

kind

ofType {

name

kind

}

}

}

}

}

}

}

yields

{

"__schema":{

"queryType":{

"fields":[

// This array may have other entries

{

"name":"node",

"type":{

"name":"Node",

"kind":"INTERFACE"

},

"args":[

{

"name":"id",

"type":{

"kind":"NON_NULL",

"ofType":{

"name":"ID",

"kind":"SCALAR"

}

}

}

]

}

]

}

}

}

If two objects appear in a query, both implementing with identical IDs, then the two objects must be equal.

For the purposes of this definition, object equality is defined as follows:

  • If a field is queried on both objects, the result of querying that field on the first object must be equal to the result of querying that field on the second object.
    • If the field returns a scalar, equality is defined as is appropriate for that scalar.
    • If the field returns an enum, equality is defined as both fields returning the same enum value.
    • If the field returns an object, equality is defined recursively as per the above.

For example:

{

fourNode: node(id:"4"){

id

...on User {

name

userWithIdOneGreater {

id

name

}

}

}

fiveNode: node(id:"5"){

id

...on User {

name

userWithIdOneLess {

id

name

}

}

}

}

might return:

{

"fourNode":{

"id":"4",

"name":"Mark Zuckerberg",

"userWithIdOneGreater":{

"id":"5",

"name":"Chris Hughes"

}

},

"fiveNode":{

"id":"5",

"name":"Chris Hughes",

"userWithIdOneLess":{

"id":"4",

"name":"Mark Zuckerberg",

}

}

}

Because and are the same, we are guaranteed by the conditions above that must be the same as , and indeed it is.

Imagine a root field named , that takes a user's username and returns the corresponding user:

{

username(username:"zuck"){

id

}

}

might return:

{

"username":{

"id":"4",

}

}

Clearly, we can link up the object in the response, the user with ID 4, with the request, identifying the object with username "zuck". Now imagine a root field named , that takes a list of usernames and returns a list of objects:

{

usernames(usernames:["zuck","moskov"]){

id

}

}

might return:

{

"usernames":[

{

"id":"4",

},

{

"id":"6"

}

]

}

For clients to be able to link the usernames to the responses, it needs to know that the array in the response will be the same size as the array passed as an argument, and that the order in the response will match the order in the argument. We call these plural identifying root fields, and their requirements are described below.

Fields#

A server compliant with this spec may expose root fields that accept a list of input arguments, and returns a list of responses. For spec-compliant clients to use these fields, these fields must be plural identifying root fields, and obey the following requirements.

NOTE Spec-compliant servers may expose root fields that are not plural identifying root fields; the spec-compliant client will just be unable to use those fields as root fields in its queries.

Plural identifying root fields must have a single argument. The type of that argument must be a non-null list of non-nulls. In our example, the field would take a single argument named , whose type (using our type system shorthand) would be .

The return type of a plural identifying root field must be a list, or a non-null wrapper around a list. The list must wrap the interface, an object that implements the interface, or a non-null wrapper around those types.

Whenever the plural identifying root field is used, the length of the list in the response must be the same as the length of the list in the arguments. Each item in the response must correspond to its item in the input; more formally, if passing the root field an input list resulted in output value , then for an arbitrary permutation , passing the root field must result in output value .

Because of this, servers are advised to not have the response type wrap a non-null wrapper, because if it is unable to fetch the object for a given entry in the input, it still must provide a value in the output for that input entry; is a useful value for doing so.

Continue Reading →CachingSours: https://graphql.org/learn/global-object-identification/

Schemas and Types

On this page, you'll learn all you need to know about the GraphQL type system and how it describes what data can be queried. Since GraphQL can be used with any backend framework or programming language, we'll stay away from implementation-specific details and talk only about the concepts.

Type system#

If you've seen a GraphQL query before, you know that the GraphQL query language is basically about selecting fields on objects. So, for example, in the following query:

  1. We start with a special "root" object
  2. We select the field on that
  3. For the object returned by , we select the and fields

Because the shape of a GraphQL query closely matches the result, you can predict what the query will return without knowing that much about the server. But it's useful to have an exact description of the data we can ask for - what fields can we select? What kinds of objects might they return? What fields are available on those sub-objects? That's where the schema comes in.

Every GraphQL service defines a set of types which completely describe the set of possible data you can query on that service. Then, when queries come in, they are validated and executed against that schema.

Type language#

GraphQL services can be written in any language. Since we can't rely on a specific programming language syntax, like JavaScript, to talk about GraphQL schemas, we'll define our own simple language. We'll use the "GraphQL schema language" - it's similar to the query language, and allows us to talk about GraphQL schemas in a language-agnostic way.

Object types and fields#

The most basic components of a GraphQL schema are object types, which just represent a kind of object you can fetch from your service, and what fields it has. In the GraphQL schema language, we might represent it like this:

type Character {

name:String!

appearsIn:[Episode!]!

}

The language is pretty readable, but let's go over it so that we can have a shared vocabulary:

  • is a GraphQL Object Type, meaning it's a type with some fields. Most of the types in your schema will be object types.
  • and are fields on the type. That means that and are the only fields that can appear in any part of a GraphQL query that operates on the type.
  • is one of the built-in scalar types - these are types that resolve to a single scalar object, and can't have sub-selections in the query. We'll go over scalar types more later.
  • means that the field is non-nullable, meaning that the GraphQL service promises to always give you a value when you query this field. In the type language, we'll represent those with an exclamation mark.
  • represents an array of objects. Since it is also non-nullable, you can always expect an array (with zero or more items) when you query the field. And since is also non-nullable, you can always expect every item of the array to be an object.

Now you know what a GraphQL object type looks like, and how to read the basics of the GraphQL type language.

Arguments#

Every field on a GraphQL object type can have zero or more arguments, for example the field below:

type Starship {

id:ID!

name:String!

length(unit:LengthUnit= METER):Float

}

All arguments are named. Unlike languages like JavaScript and Python where functions take a list of ordered arguments, all arguments in GraphQL are passed by name specifically. In this case, the field has one defined argument, .

Arguments can be either required or optional. When an argument is optional, we can define a default value - if the argument is not passed, it will be set to by default.

The Query and Mutation types#

Most types in your schema will just be normal object types, but there are two types that are special within a schema:

schema{

query:Query

mutation:Mutation

}

Every GraphQL service has a type and may or may not have a type. These types are the same as a regular object type, but they are special because they define the entry point of every GraphQL query. So if you see a query that looks like:

That means that the GraphQL service needs to have a type with and fields:

type Query {

hero(episode:Episode):Character

droid(id:ID!):Droid

}

Mutations work in a similar way - you define fields on the type, and those are available as the root mutation fields you can call in your query.

It's important to remember that other than the special status of being the "entry point" into the schema, the and types are the same as any other GraphQL object type, and their fields work exactly the same way.

Scalar types#

A GraphQL object type has a name and fields, but at some point those fields have to resolve to some concrete data. That's where the scalar types come in: they represent the leaves of the query.

In the following query, the and fields will resolve to scalar types:

We know this because those fields don't have any sub-fields - they are the leaves of the query.

GraphQL comes with a set of default scalar types out of the box:

  • : A signed 32‐bit integer.
  • : A signed double-precision floating-point value.
  • : A UTF‐8 character sequence.
  • : or .
  • : The ID scalar type represents a unique identifier, often used to refetch an object or as the key for a cache. The ID type is serialized in the same way as a String; however, defining it as an signifies that it is not intended to be human‐readable.

In most GraphQL service implementations, there is also a way to specify custom scalar types. For example, we could define a type:

scalar Date

Then it's up to our implementation to define how that type should be serialized, deserialized, and validated. For example, you could specify that the type should always be serialized into an integer timestamp, and your client should know to expect that format for any date fields.

Enumeration types#

Also called Enums, enumeration types are a special kind of scalar that is restricted to a particular set of allowed values. This allows you to:

  1. Validate that any arguments of this type are one of the allowed values
  2. Communicate through the type system that a field will always be one of a finite set of values

Here's what an enum definition might look like in the GraphQL schema language:

enum Episode {

NEWHOPE

EMPIRE

JEDI

}

This means that wherever we use the type in our schema, we expect it to be exactly one of , , or .

Note that GraphQL service implementations in various languages will have their own language-specific way to deal with enums. In languages that support enums as a first-class citizen, the implementation might take advantage of that; in a language like JavaScript with no enum support, these values might be internally mapped to a set of integers. However, these details don't leak out to the client, which can operate entirely in terms of the string names of the enum values.

Lists and Non-Null#

Object types, scalars, and enums are the only kinds of types you can define in GraphQL. But when you use the types in other parts of the schema, or in your query variable declarations, you can apply additional type modifiers that affect validation of those values. Let's look at an example:

type Character {

name:String!

appearsIn:[Episode]!

}

Here, we're using a type and marking it as Non-Null by adding an exclamation mark, after the type name. This means that our server always expects to return a non-null value for this field, and if it ends up getting a null value that will actually trigger a GraphQL execution error, letting the client know that something has gone wrong.

The Non-Null type modifier can also be used when defining arguments for a field, which will cause the GraphQL server to return a validation error if a null value is passed as that argument, whether in the GraphQL string or in the variables.

Lists work in a similar way: We can use a type modifier to mark a type as a , which indicates that this field will return an array of that type. In the schema language, this is denoted by wrapping the type in square brackets, and . It works the same for arguments, where the validation step will expect an array for that value.

The Non-Null and List modifiers can be combined. For example, you can have a List of Non-Null Strings:

myField:[String!]

This means that the list itself can be null, but it can't have any null members. For example, in JSON:

myField:null

myField:[]

myField:['a','b']

myField:['a',null,'b']

Now, let's say we defined a Non-Null List of Strings:

myField:[String]!

This means that the list itself cannot be null, but it can contain null values:

myField:null

myField:[]

myField:['a','b']

myField:['a',null,'b']

You can arbitrarily nest any number of Non-Null and List modifiers, according to your needs.

Interfaces#

Like many type systems, GraphQL supports interfaces. An Interface is an abstract type that includes a certain set of fields that a type must include to implement the interface.

For example, you could have an interface that represents any character in the Star Wars trilogy:

interface Character {

id:ID!

name:String!

friends:[Character]

appearsIn:[Episode]!

}

This means that any type that implements needs to have these exact fields, with these arguments and return types.

For example, here are some types that might implement :

type Human implements Character {

id:ID!

name:String!

friends:[Character]

appearsIn:[Episode]!

starships:[Starship]

totalCredits:Int

}

type Droid implements Character {

id:ID!

name:String!

friends:[Character]

appearsIn:[Episode]!

primaryFunction:String

}

You can see that both of these types have all of the fields from the interface, but also bring in extra fields, , and , that are specific to that particular type of character.

Interfaces are useful when you want to return an object or set of objects, but those might be of several different types.

For example, note that the following query produces an error:

The field returns the type , which means it might be either a or a depending on the argument. In the query above, you can only ask for fields that exist on the interface, which doesn't include .

To ask for a field on a specific object type, you need to use an inline fragment:

Learn more about this in the inline fragments section in the query guide.

Union types#

Union types are very similar to interfaces, but they don't get to specify any common fields between the types.

union SearchResult =Human|Droid|Starship

Wherever we return a type in our schema, we might get a , a , or a . Note that members of a union type need to be concrete object types; you can't create a union type out of interfaces or other unions.

In this case, if you query a field that returns the union type, you need to use an inline fragment to be able to query any fields at all:

The field resolves to a which lets you differentiate different data types from each other on the client.

Also, in this case, since and share a common interface (), you can query their common fields in one place rather than having to repeat the same fields across multiple types:

{

search(text:"an"){

__typename

...on Character {

name

}

...on Human {

height

}

...on Droid {

primaryFunction

}

...on Starship {

name

length

}

}

}

Note that is still specified on because otherwise it wouldn't show up in the results given that is not a !

Input types#

So far, we've only talked about passing scalar values, like enums or strings, as arguments into a field. But you can also easily pass complex objects. This is particularly valuable in the case of mutations, where you might want to pass in a whole object to be created. In the GraphQL schema language, input types look exactly the same as regular object types, but with the keyword instead of :

input ReviewInput {

stars:Int!

commentary:String

}

Here is how you could use the input object type in a mutation:

The fields on an input object type can themselves refer to input object types, but you can't mix input and output types in your schema. Input object types also can't have arguments on their fields.

Continue Reading →ValidationSours: https://graphql.org/learn/schema/
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Should I handle a GraphQL ID as a string on the client?

is a scalar type described in the GraphQL specification (working draft October 2016):

The ID type is serialized in the same way as a String; however, it is not intended to be human‐readable. While it is often numeric, it should always serialize as a String.


Your observation

I can use GraphQL to query the MySQL db with either a string or a integer that matches the ID value in the database. However, GraphQL will always return the ID value as a string.

is aligned with the specification about result coercion:

GraphQL is agnostic to ID format, and serializes to string to ensure consistency across many formats ID could represent

and input coercion:

When expected as an input type, any string (such as "4") or integer (such as 4) input value should be coerced to ID as appropriate for the ID formats a given GraphQL server expects


How should I be handling this value in the client?

  • When working with results, treat them as strings.
  • When using inputs (in GraphQL variables or input parameters for mutations or queries), you can either use integers or strings.

Should I always convert it to an integer as soon as I get it from GraphQL?

That's highly depending on your application. There is no general rule that dictates a clear "yes" or "no" here.

Should I modify my sequelize code to store the ID value as a string?

No, that's not required.

The GraphQL specification about the type does not cover how you store the ids, only how a GraphQL server is expected to treat input and output. It's up to the GraphQL layer to ensure this behaviour. How ids are handled in the actual storage is up to the storage layer.

Is there a correct way to proceed when using GraphQL IDs like this?

I hope the above answers also answer this question :)

Sours: https://stackoverflow.com/q/47874344

IDs

Dgraph provides two types of built-in identifiers: the scalar type and the directive.

  • The scalar type is used when you don’t need to set an identifier outside of Dgraph.
  • The directive is used for external identifiers, such as email addresses.

The type

In Dgraph, every node has a unique 64-bit identifier that you can expose in GraphQL using the type. An is auto-generated, immutable and never reused. Each type can have at most one field.

The type works great when you need to use an identifier on nodes and don’t need to set that identifier externally (for example, posts and comments).

For example, you might set the following type in a schema:

In a single-page app, you could generate the page for when a user clicks to view the post with 0x123. Your app can then use a GraphQL query to fetch the data used to generate the page.

For input and output, s are treated as strings.

You can also update and delete posts by .

The directive

For some types, you’ll need a unique identifier set from outside Dgraph. A common example is a username.

The directive tells Dgraph to keep that field’s values unique and use them as identifiers.

For example, you might set the following type in a schema:

Dgraph requires a unique username when creating a new user. It generates the input type for with , so you can’t make an add mutation without setting a username; and when processing the mutation, Dgraph will ensure that the username isn’t already set for another node of the type.

In a single-page app, you could render the page for when a user clicks to view the author bio page for that user. Your app can then use a GraphQL query to fetch the data and generate the page.

Identities created with are reusable. If you delete an existing user, you can reuse the username.

Fields with the directive must have the type .

As with types, Dgraph generates queries and mutations so you can query, update, and delete data in nodes, using the fields with the directive as references.

It’s possible to use the directive on more than one field in a type. For example, you can define a type like the following:

You can then use multiple fields in arguments to queries, and while searching, these fields will be combined with the operator, resulting in a Boolean operation. For example, for the above schema, you can send a query like the following:

This will yield a positive response if both the and match any data in the database.

Combining and

You can use both the type and the directive on another field definition to have both a unique identifier and a generated identifier.

For example, you might define the following type in a schema:

With this schema, Dgraph requires a unique when creating a new user. This schema provides the benefits of both of the previous examples above. Your app can then use the query to provide either the Dgraph-generated or the externally-generated .

Note If in a type there are multiple fields, then in a query these arguments will be optional. If in a type there’s only one field defined with either or , then that will be a required field in the query’s arguments.

Sours: https://dgraph.io/docs/graphql/schema/ids/

Id type graphql

When to use GraphQLID instead of GraphQLInt?

I had a look at the GraphQL spec.

The ID scalar type represents a unique identifier, often used to refetch an object or as the key for a cache. The ID type is serialized in the same way as a ; however, it is not intended to be human‐readable. While it is often numeric, it should always serialize as a .

– https://spec.graphql.org/April2016/#sec-ID

That answers the question whether it is left to implementation or dictated by the spec, i.e. ID should be always serialized to a .

In addition, in the context of an input type, input needs to be coerced into a string. From the spec:

Input Coercion

When expected as an input type, any string (such as ) or integer (such as ) input value should be coerced to ID as appropriate for the ID formats a given GraphQL server expects. Any other input value, including float input values (such as ), must raise a query error indicating an incorrect type.

That leaves me with the original problem.

I have a mysql backend where my PK are integers.

The way I see it, I have these options:

  • Start using UUIDs for PKs. However, this has performance implications.
  • Ignore the implicit requirement (originating in the relayjs ecosystem) to have the ID unique across the application, and cast IDs to number when possible for internal consumption.
  • Hash Encode IDs on the application data layer, e.g. UUID derived from a concatenation of table name & PK value.

I am going with the latter option. This is also the approach that has adopted via and .

Sours: https://stackoverflow.com/questions/39471075/when-to-use-graphqlid-instead-of-graphqlint
Learn GraphQL In 40 Minutes

Basic Types

In most situations, all you need to do is to specify the types for your API using the GraphQL schema language, taken as an argument to the function.

The GraphQL schema language supports the scalar types of , , , , and , so you can use these directly in the schema you pass to .

By default, every type is nullable - it's legitimate to return as any of the scalar types. Use an exclamation point to indicate a type cannot be nullable, so is a non-nullable string.

To use a list type, surround the type in square brackets, so is a list of integers.

Each of these types maps straightforwardly to JavaScript, so you can just return plain old JavaScript objects in APIs that return these types. Here's an example that shows how to use some of these basic types:

var express =require('express');

var{ graphqlHTTP }=require('express-graphql');

var{ buildSchema }=require('graphql');

var schema =buildSchema(`

type Query {

quoteOfTheDay: String

random: Float!

rollThreeDice: [Int]

}

`);

var root ={

quoteOfTheDay:()=>{

return Math.random()<0.5?'Take it easy':'Salvation lies within';

},

random:()=>{

return Math.random();

},

rollThreeDice:()=>{

return[1,2,3].map(_ =>1+ Math.floor(Math.random()*6));

},

};

var app =express();

app.use('/graphql',graphqlHTTP({

schema: schema,

rootValue: root,

graphiql:true,

}));

app.listen(4000);

console.log('Running a GraphQL API server at localhost:4000/graphql');

If you run this code with and browse to http://localhost:4000/graphql you can try out these APIs.

These examples show you how to call APIs that return different types. To send different types of data into an API, you will also need to learn about passing arguments to a GraphQL API.

Continue Reading →Passing ArgumentsSours: https://graphql.org/graphql-js/basic-types/

Now discussing:

Scalar types in AWS AppSync

A GraphQL object type has a name and fields, and those fields can have sub-fields. Ultimately, an object type's fields must resolve to scalar types, which represent the leaves of the query. For more information about object types and scalars, see Schemas and Types on the GraphQL website.

In addition to a default set of GraphQL scalars, AWS AppSync includes a set of reserved scalars that start with an AWS prefix. AWS AppSync does not support custom scalars.

Note

You cannot use AWS as a prefix for custom object types.

GraphQL defines the following default scalars:

A unique identifier for an object. This scalar is serialized like a but isn't meant to be human-readable.

A UTF-8 character sequence.

An integer value between -(231) and 232-1.

An IEEE 754 floating point value.

A Boolean value, either or .

AWS AppSync defines the following scalars:

Note

The , , and scalars can optionally include a time zone offset. For example, the values , , and are all valid for . The time zone offset must be either (UTC) or an offset in hours and minutes (and, optionally, seconds). For example, . The seconds field in the time zone offset is considered valid even though it's not part of the ISO 8601 standard.

An integer value representing the number of seconds before or after .

An email address in the format as defined by RFC 822.

A JSON string. Any valid JSON construct is automatically parsed and loaded in the resolver mapping templates as maps, lists, or scalar values rather than as the literal input strings. Unquoted strings or otherwise invalid JSON result in a GraphQL validation error.

A phone number. This value is stored as a string. Phone numbers can contain either spaces or hyphens to separate digit groups. Phone numbers without a country code are assumed to be US/North American numbers adhering to the North American Numbering Plan (NANP).

A URL as defined by RFC 1738. For example, or . URLs must contain a schema (, ) and can't contain two forward slashes () in the path part.

A valid IPv4 or IPv6 address. IPv4 addresses are expected in quad-dotted notation (). IPv6 addresses are expected in non-bracketed, colon-separated format (). You can include an optional CIDR suffix () to indicate subnet mask.

Schema usage example

If you're unfamiliar with creating GraphQL APIs in AWS AppSync, or with connecting resolvers with mapping templates, we recommend first reviewing Designing a GraphQL API and Resolver tutorials.

The following example GraphQL schema uses all of the custom scalars as an "object" and shows the resolver request and response templates for basic put, get, and list operations. Finally, the example shows how you can use this when running queries and mutations.

Use the following request template for :

The response template for is:

Use the following request template for :

The response template for is:

Use the following request template for :

The response template for is:

The following are some examples of using this schema with GraphQL queries:

Sours: https://docs.aws.amazon.com/appsync/latest/devguide/scalars.html


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