Graphql Nested Types

A GraphQL query must contain a selection set on any field that returns an object type, and selection sets are not allowed on fields that return scalar types, such as Int or String. Aside from controlling the flattening process, the Spry Pre-Release 1. The query below returns a list of products with their. Prisma is 100% compatible with the GraphQL & Apollo ecosystem: It works with Apollo Server, Apollo Client and Apollo Engine. In order to avoid name clashes with the deeply nested types that Apollo generates, it is recommended that the suffix “Fragment” is added for each fragment you write. js So, you’re probably thinking — is this just another hullabaloo GraphQL tutorial that is just going to say a lot of big words but not actually help me implement anything?. Since it’s pretty expensive to load all of the product types from a database on every single request, we decided to go with a hybrid approach where we are generating and storing GraphQL schema extensions in. The resolver is basically a call back function for each field. For this purpose need to take ObjectTypeComposer helper from graphql-compose package. But I am getting sidetracked, let’s connect to GraphQL using Python and get some data back! Getting Started Assuming you already have Python installed the main modules you need are: 1. The ticket will cover location, breakfast, lunch, snacks and coffee for the participants. However, the schema doesn't define where the data comes from. In this course, learn how to get started with GraphQL. Time for more dynamic GraphQL resolvers, nested relations and async/await! ----- No. GraphQL—a query language for APIs that was originally built by Facebook—allows developers to choose the kinds of requests they want to make, and receive information on multiple facets of that. Conceptual Model. The GraphQL schema provided to the Apollo Server is all of the available data for reading and writing data via GraphQL. In this tutorial, you will learn how to use Storyblok’s new GraphQL api with React and Apollo - the most famous GraphQL client. GraphQL schema is nested in your GraphQL server and defines every functionality available to the clients. This should. We'll start by mastering the fundamentals of GraphQL, including data types, schemas, and integration with Express and React. If you didn't provide a GraphQL schema, we try to derive one from the existing graph data. Serverless GraphQL Backend Architecture 1. Connections are links between related objects. php file ' GraphQL ' => Folklore\GraphQL\Support\Facades\ GraphQL:: class, 3-Publish the configuration file $ php artisan vendor:publish --provider= " Folklore\GraphQL\ServiceProvider " 4-Review the configuration file. If your query string contains variables, you can provide values in a hash of { String => value } pairs. getHeaders(). My question is: is it allowed to use type conditions on nested fields in graphql queries? Or type conditions have to be used on the top level types returned by the queries? If it's allowed, how should I fix my types/queries? Thanks a lot!. If we’re not careful we can end up with a large number of inefficient queries. The mime type of the response is application/json. Next, we'll request a nested object for the organization. The Apollo toolset can be used to create a GraphQL client, GraphQL server, and other complementary applications, but you will use the Apollo Client for your React client-side application. Download [FreeCourseSite. GraphQL\Type\Schema: graphql-php never modifies this value and passes it as is to all underlying the values inside it can be nested using \stdClass if desired. You can also configure a single GraphQL API to deliver private data using more than one authorization type. The "api" field of security rule can take values following the format graphql. Since Flow is all about defining types, it's no suprise these two topics can easily go hand in hand. Introduction. GraphQL is a great way to let the client decide which data they want to be transmitted over the network, rather than having the server send a fixed set of data. Introspection. The GraphQL schema requires a special annotation to say that a value cannot be null, !. If you have a tracked table in your database, its insert/update/delete mutation fields are added as nested fields under the mutation_root root level type. A GraphQL query must contain a selection set on any field that returns an object type, and selection sets are not allowed on fields that return scalar types, such as Int or String. GraphQL creates a uniform API across your entire application without being limited by a specific storage engine. GraphQL Type Definitions. Support field arguments with complex types. 🚀 When it comes to microservices orchestration, GraphQL provides you with two different and complete ways of providing the best architecture for your back-end. In order to convert the GraphQL query to PHP array, graphql-php traverses query fields (using depth-first algorithm) and runs special resolve function on each field. Add GraphQL. We use inner classes to logically group classes and interfaces in one place so that it can be more readable and maintainable. A simple tutorial on how to create a Node. Here is an excerpt from the introduction: GraphQL is a query language for your API, and a server-side runtime for executing queries by using a type system you define for your data. …So the first thing I want to do here…is query the repository fields. The database of the GraphQL service is reset periodically, so you can change the data with mutations as you like. Converts queries to SPARQL. So, Why GraphQL? If you're already sold on GraphQL, you can skip this section. type Mutation {createDraft (title: String!, text: String): Post publish (id: ID!. That said, Facebook (and others like GitHub) switching from RESTish to GraphQL makes folks consider GraphQL as a replacement for REST. Retrieve multiple data records. So, the parent (User) resolves a certain field (metrics). From the GraphQL documentation, they define it as "GraphQL is a query language for your API, and a server-side runtime for executing queries by using a type system you define for your data. The GitHub GraphQL API v4 represents an architectural and conceptual shift from the GitHub REST API v3. If we’re not careful we can end up with a large number of inefficient queries. PM> Install-Package GraphQL. Schema stitching is the process of creating a single GraphQL schema from multiple underlying GraphQL APIs. Types are further subdivided into the disjoint sets object types ( ), interface types ( ), union types ( ) and scalars. Start to Inspect. This library uses graphql-java under the hood for parsing of schema and queries, and managing the GraphQL state and context. GraphQL dispenses with that terminology, but is still very much RPCish. There are fifteen Type Definitions in total for types such as Albums, Galleries, Images, and Tags. Gatsby uses GraphQL at build-time and not for live sites. The Apollo GraphQL client can generate types based on queries in your frontend code. If we have these two types together, the type has to implement both of these structures. Also I wanted to use discriminator feature for two types of Tickets. And right away, we know which fields are available for our response. In GraphQL, an API defines a set of types that it uses to validate queries. Input Types. This is typically allowed for both reading and writing. If you click on the left side Schema button you will see a Query which is the same query we created above in Type defs. In this video, I show you how to do it with. You can use the object (one-to-one) or array (one-to-many) relationships defined in your schema to make a nested query i. GraphQL Leveler is a library for GraphQL servers which allows them to provide a great deal of flexibility to their clients when it comes to response shape. You can read up a bit more in the spec, and possibley other topics regarding the same in discuss. Written down in Schema Definition Language (SDL), basic components of a GraphQL schema — types — describe kinds of object that can be queried on that server and the fields they have. Each level of the query corresponds to a type and each type contains a set of fields which in turn may be nested types. The schema defines what queries are allowed to be made, what types of data can be fetched, and the relationships between these types. During this task (and others I've came across in the past) I'm met with heavily wrapped objects. Maximum is 50. But not for nested field resolvers or data fetching. GraphQL, the new kid on the block of querying syntax, gives great importance to the request of the client. You can nest types in GraphQL, so you can sometimes save on the amount of data you need to fetch from the database. So, for example, you can get just the Title and Description of an entry, instead of the data of all the fields, in a response. It is an alternative. RESTful APIs is a well-understood architecture for web and app backends. Suppose we want to add a custom resolver to delete a Post. This tutorial is part two of a four part series, which aims to take you from scratch to deploying a fully functional full stack application. GraphQL creates a uniform API across your entire application without being limited by a specific storage engine. 5 introduces the concept of a "Nested Data Set". apollo-upload-server is a library that allows you to upload files in graphql mutations without needing to create a REST endpoint to handle these uploads. So, for example, you can get just the Title and Description of an entry, instead of the data of all the fields, in a response. I hate Stripe. The idea was that these operations would then mutate the parent entity. " So as you can see, GraphQL proposes a change in the way a client asks for data from a server. The pane on the right side enables you to click through the operations, including queries, mutations, and subscriptions that your schema has exposed. * * More sophisticated GraphQL servers, such as those which persist queries, * may wish to separate the validation and execution phases to a static time * tooling step, and a server runtime step. The main element of each schema is type which allows establishing relations between different types, define allowed GraphQL operations (Queries and Mutations) to be performed on the server and more. Both OSX and Windows supported. Hi Kristijan, I am trying to learn GraphQL and need some help. Learn how to optimize the performance of your queries. These Type Definitions are quite long, usually over 100 lines each, so I'll omit them for. Moving Beyond REST With GraphQL - DZone. So here we want to create types that are based upon the structure of the data we store in mongo and will return to the client. In this post we'll explore the benefits of GraphQL over REST, and build a feature rich webshop using Graphcool and the Serverless Framework. fgraphql can produce anything fastJoin can because its resolvers can (only when absolutely necessary!) directly manipulate the parent record. Java inner class or nested class is a class which is declared inside the class or interface. Before building our GraphQL API, let's first introduce GraphQL and the advantages it offers over the REST way of building APIs. A simple tutorial on how to create a Node. buildNeo4jResolvers then generates any unprovided resolvers for query and mutation types that were generated or that use a @cypher directive. 3 Multi fields. However, the cool thing is that, by unifying many GraphQL APIs into one, Apollo will forward types for you, no need to reimplement all abstracted sources resolvers. A service can extend GraphQL types that are defined by other services, and it can define types for other services to extend. A deeply nested query that cross boundaries a few times can create an avalanche of requests from your gateway. GraphQL is a strongly typed language. " So as you can see, GraphQL proposes a change in the way a client asks for data from a server. class GraphQLList A type wrapper around other types that represents a list of those types. In a nutshell, GraphQL is a syntax that describes how to ask for data, and is generally used to load data from a server to a client. To return specific properties of the object, you’ll need to specify the object’s type using an Inline Fragment. You can connect data between them by extending types and creating references with the @key directive. , one for fat, one for sugar, and so on as depicted in the figure below:. type Mutation {createDraft (title: String!, text: String): Post publish (id: ID!. React and Relay. But I am getting sidetracked, let’s connect to GraphQL using Python and get some data back! Getting Started Assuming you already have Python installed the main modules you need are: 1. Maneja tus datos de manera sencilla en el backend y en el frontend con GraphQL. * Part 1: How to build blazing fast REST APIs with Node. Join us on June 15 in Berlin and see expert speakers from top GraphQL companies as well as the GraphQL creators Lee Byron and Nick Schrock. example, we can just look at the schema for the nested object. How to deal with nested input in GraphQL When writing queries I can define a resolver on any field and that field's value will be determined by its resolver, regardless of query depth. In other words, an object type is composed of multiple scalar types or object types. GraphQL Apollo Server with Node. php file in order to describe how data are shaped (via GraphQL types) and what data on the server can be queried or mutated. The type system helps to define the schema, which is a contract between client and server. They define the shape of the JSON object that should be returned. As a result, problems arise when a client requests too many nested fields at once. For example, we might have a schema. If you click on the left side Schema button you will see a Query which is the same query we created above in Type defs. Most standard JSON parsers require the entire string or file to be read into memory, which can cause issues when the responses are large. GraphQL bindings enable accessing a GraphQL API from your programming language. Luckily, this problem has gotten a lot of attention in the GraphQL community and has known work arounds depending on the particular tools you are working with. In other words, an object type is composed of multiple scalar types or object types. These entities are also related to each other; for example, a user has many posts, a photo belongs to an album, etc. Introspection. But I am getting sidetracked, let’s connect to GraphQL using Python and get some data back! Getting Started Assuming you already have Python installed the main modules you need are: 1. GraphQL has three main characteristics: It lets the client specify exactly what data it needs. We implemented two post-quantum (i. GraphQL Batch is now considered general best-practice for all GraphQL work at Shopify. The entire type system is called the schema. Summary Got to the end of this comment for the solution, I think I've got it. Then resolvers come into. When retrieving articles' data, it makes more sense to fetch belonging author's data as well instead of "author_id". Learn how nesting works in GraphQL. Relay expects the client schema to be located in your --src directory. It is expected subsequent calls to getType, getEnumType, getMutationType, and getQueryType will return the same instance (cached). The main question was if you could return a recursively nested object (without knowing the depth) in a single query. Merge Graphql Schemas. Strato has existed at Twitter much longer than GraphQL, and is used to power the GraphQL API. As i said getAlltodos Query help us to get the array of todos let’s test it now by running a query on the graphql playground. The GitHub GraphQL API v4 represents an architectural and conceptual shift from the GitHub REST API v3. Usually you only use it as the starting point of a query, but it can actually go anywhere you want. GraphQL, the new kid on the block of querying syntax, gives great importance to the request of the client. Time for more dynamic GraphQL resolvers, nested relations and async/await! ----- No. type Mutation {createDraft (title: String!, text: String): Post publish (id: ID!. In this tutorial, you will learn how to use Storyblok’s new GraphQL api with React and Apollo - the most famous GraphQL client. Arguments serve the same purpose as your traditional query parameters or URL segments in REST. A query requesting the name and address of a particular employee, for example, could look like the following example. It is an alternative. GraphQL provides a basic set of well‐defined Scalar types. This GraphQL tutorial will help you master the fundamental concepts in structuring GraphQL servers. GraphQL—a query language for APIs that was originally built by Facebook—allows developers to choose the kinds of requests they want to make, and receive information on multiple facets of that. This page will walk you through a series of GraphQL queries, each designed to demonstrate a particular feature of GraphQL. All remaining. This complex filtering functionality is available in neo4j-graphql. The data inside the nested data set is determined by the current row of the parent data set. One nice lib it requires is the overblog/graphql-php-generator that is responsible for reading a nice and clean yml file and converting it into the GraphQL type objects. In the GraphQL schema, the argument appears after the field name. GraphQL is a perfect fit when you need to expose complex data representations, and when clients might need only a subset of the data, or they regularly perform nested queries to get the data they need. Each type specifies the data that the type contains, and the relationships it has to other types. By using the type system, it can be predetermined whether a GraphQL query is valid or not. An example of an advanced approach to GraphQL API using Python and Django for a mobile application GraphQL with Python and Django - Advanced · AnvilEight Blog ← Home Archive Tags About RSS AnvilEight. It can further have fields and nested fields representing other data fields. js and export a funtion that accepts a token and returns an instance of Apollo Client. Using your code, I wanted to embed Members inside Projects (subdocument) and then connect them to Tickets. The object type is the most common type used in a schema and represents a group of fields. By voting up you can indicate which examples are most useful and appropriate. Often clients need to make complex requests to request ordered, sorted, filtered data, sub set (for pagination) or request nested objects. GraphiQL might show some errors since it does not know how to handle the jsonb type. For example an Order has a DeliveryAddress and a ICollectio of Position. The files to be uploaded can then be nested anywhere in GraphQL mutations using variables as follows:. GraphQL terminology; Discovering the GraphQL API; GraphQL terminology. There is only one endpoint you need to speak to, and you can use types to pick and choose which data fields you wish to express in your view. In the following query, the name and appearsIn fields will resolve to scalar types:. GraphQL isn't tied to any specific database or storage engine and is instead backed by your existing code and data. The body of the fragment defines the fields that will be queried for; Benefits of using a GraphQL fragment. @leebyron Sorry for confusing name. Instructions. GraphQL is similar - technically any query could be implemented to cause a data write. 8 (41 ratings) Course Ratings are calculated from individual students’ ratings and a variety of other signals, like age of rating and reliability, to ensure that they reflect course quality fairly and accurately. Net to your project via the Package Manager Console. It is an alternative. For this purpose need to take ObjectTypeComposer helper from graphql-compose package. Learn how nesting works in GraphQL. type Mutation {createDraft (title: String!, text: String): Post publish (id: ID!. An example I have in mind is a blog post. Support field arguments with complex types. A GraphQL query must contain a selection set on any field that returns an object type, and selection sets are not allowed on fields that return scalar types, such as Int or String. I tried to reduce the verbosity a bit by using alias names for the most frequently used GraphQL types. Why GraphQL? GraphQL accelerates the arrival of your query’s response by preventing unneeded requests or bootstraps of the back end. To return specific properties of the object, you’ll need to specify the object’s type using an Inline Fragment. To target those fields in GraphQL SDL, you can provide a full type definition for the nested type, which can be arbitrarily named (as long as the name is unique in the schema). Data of all tables in the database tracked by the GraphQL engine can be modified over the GraphQL endpoint. The reason is that the GraphQL needs two different structures. I have some simple base types which are nested into Int1, Int2, which in turn are nested in Top. The idea was that these operations would then mutate the parent entity. As noted from the above, three object types – ‘Artist’, ‘Album’ and ‘Track’ – have been defined in GraphQL schema. ; Type inference is a technique used by. The snapshot below shows a GraphQL API configured to use API Key as the default authorization type. Any standards-compliant GraphQL implementation supports some built-in introspection query types that provide information about the available object and field types. This article describes how GraphQL is implemented in "Spidey", an exemplary microservices based online store. And right away, we know which fields are available for our response. Let's create a simple API with two types that reference each other. Here are the examples of the python api graphql. It uses an extension called the multipart request spec to handle file transfers. In this tutorial, we're going to build an Elasticsearch-backed GraphQL API on AWS AppSync. Now you have defined the schema and the events query, it is time to create an object to handle the queries. GraphQL helps to keep the two aspects of data retrieval and data type definition separate: (1) GraphQL provides the capabilities to describe the data served by the API with a rigorous type system. In this work, we introduce GraphQL-LD, an approach for extending GraphQL queries with a JSON-LD context , so that they can be used to evaluate queries over RDF data. GraphQL dispenses with that terminology, but is still very much RPCish. Afterward, you were able to store the result in React's local state to display it later. You used a configured axios client instance for it. Usually you only use it as the starting point of a query, but it can actually go anywhere you want. …Let's make our query a little bit more complicated…by adding multiple nested fields. It is expected subsequent calls to getType, getEnumType, getMutationType, and getQueryType will return the same instance (cached). Neo4j however doesn't handle nested properties very well. A GraphQL ID can be used with the global node query to quickly return properties of a node, without having to query through nested layers of data. GraphQL is a query language that bears some superficial similarities with JSON. GraphQL isn't tied to any specific database or storage engine and is instead backed by your existing code and data. A deeply nested query that cross boundaries a few times can create an avalanche of requests from your gateway. fetch data for a type along with data from a nested or related type. graphql like: schema { query: Root } type Root { dictionary: [Word] } type Word { id: String! definition: WordDefinition } type WordDefinition { text: String image: String } Source files. This section is all about GraphQL type definitions and how they are used to define the overall GraphQL schema. This is how you use fragments to extract and reuse parts of your queries. This results in a high abstraction layer on top of databases, but sometimes more is needed to satisfy specific data requirements of modern applications. …We'll also throw in some arguments for good measure. Comparing GraphQL to REST, queries operate like GET requests, while mutations operate like POST / PATCH / DELETE. js, MongoDB - GraphQL API Si esta es tu primera visita, asegúrate de consultar la Ayuda haciendo clic en el vínculo de arriba. If your query string contains variables, you can provide values in a hash of { String => value } pairs. In order to create a Type, you have to give it a unique name and specify it's fields list. You can use any underlying data storage engine, including SQL or NoSQL database, plain files or in-memory data structures. By using the type system, it can be predetermined whether a GraphQL query is valid or not. @leebyron Sorry for confusing name. GraphQL examples and GraphQL code used are included. What is an input type? In GraphQL, this is a special type of argument that wraps one or more arguments up inside of itself. One of the biggest benefits of a GraphQL API is that it isn't just a flat list of endpoints — it's actually a "graph" of types that can reference each other. This bundle adds usability and readability to the GraphQL lib and was, along with the Expression Language, the reason I decided to migrate from Youshido 's lib. GraphQL has a native and highly extensible schema and type system. In plain English, it makes the client define what (nested) data it needs. In the example project, the frontmatter field on the MarkdownRemark node type is a good example. A query requesting the name and address of a particular employee, for example, could look like the following example. This results in a query language that is less expressive than SPARQL, but can still achieve many of the typical data retrieval tasks in applications. GraphQL, the new kid on the block of querying syntax, gives great importance to the request of the client. Type safe — You should never see map[string]interface{} here. apollo-upload-server is a library that allows you to upload files in graphql mutations without needing to create a REST endpoint to handle these uploads. $ php artisan graphql:publish 4- Load configuration file in bootstrap/app. If you want to grant your Nodejs GraphQL service a whole lot of the power of the MongoDb database standing behind it with very little hassle, you've come to the right place! Examples Change Log Blog Post Lets take a look at the most common use case, getMongoDbQueryResolver and getGraphQLQueryArgs: Given a simple GraphQL type:. GraphQL-LD enhances GraphQL with RDF. Write GraphQL APIs that leverage your existing data and code with GraphQL engines available in many languages. GraphQL defines the top level Query type. Add GraphQL. GraphQL is a great way to let the client decide which data they want to be transmitted over the network, rather than having the server send a fixed set of data. GraphQL Docs on Arguments. The type system helps to define the schema, which is a contract between client and server. A GraphQL ID can be used with the global node query to quickly return properties of a node, without having to query through nested layers of data. What’s your data like? Is it nested and spaghetti-like, or is it just a little interconnected?. Note: Use one GraphQL fragment for each content type in your. Nesting: Graph queries can be nested, so you can fetch data across relationships. In GraphQL, an API defines a set of types that it uses to validate queries. Arguments serve the same purpose as your traditional query parameters or URL segments in REST. How to build a GraphQL wrapper for a RESTful API in Python we have a few nested objects respective data types for the rest of the fields. Though there are technically no differences, fieldObject may be chosen for clarity to indicate that a field must contain another set of nested fields as an argument. As a result, problems arise when a client requests too many nested fields at once. Thanks to its elegant data model and expressive query language, EdgeDB greatly simplifies working with complex application data. In this case, it is the type Organization, which is a custom type defined by GitHub's GraphQL API. This is very helpful in cases where you want to fetch the new state of an object after an update. A union type within GraphQL that defines a list of implementations. Basic GraphQL queries in GDC. The filter functionality is exposed by adding a filter argument with associated inputs based on the GraphQL type definitions that expose filtering criteria. Here is an excerpt from the introduction: GraphQL is a query language for your API, and a server-side runtime for executing queries by using a type system you define for your data. Written down in Schema Definition Language (SDL), basic components of a GraphQL schema — types — describe kinds of object that can be queried on that server and the fields they have. js, MongoDB, Fastify and Swagger * Part 2: How to build a blazing fast GraphQL API with Node. GraphQL provides a basic set of well‐defined Scalar types. class GraphQLList A type wrapper around other types that represents a list of those types. Product Manager at AWS, & Me! The Amplify Framework is an open source project for building cloud-enabled mobile and web applications. Relay expects the client schema to be located in your --src directory. For example, filter for reviews created before January 1, 2015: For example, filter for reviews created before January 1, 2015:. Java inner class or nested class is a class which is declared inside the class or interface. arg, intArg, stringArg, floatArg, idArg, booleanArg. These allow you to make nested queries, gathering information from multiple objects by traversing their connections in a single GraphQL call. By continuing to browse this site, you agree to this use. In order to create a Type, you have to give it a unique name and specify it's fields list. Each type has one or more fields, which each take zero or more arguments and return a specific type. A GraphQL service is created by defining types and fields on those types, then providing functions for each field on each type. To target those fields in GraphQL SDL, you can provide a full type definition for the nested type, which can be arbitrarily named (as long as the name is unique in the schema). This course will get you up and running with GraphQL quickly, and teach you the core knowledge you need to deeply understand and build React applications quickly. The CLI automatically downloads GraphQL Introspection Schemas from the defined GraphQL endpoint and generates TypeScript or Flow classes for you. Arguments serve the same purpose as your traditional query parameters or URL segments in REST. Note that the June 2018 version of the GraphQL spec introduces multi-line strings using the """ syntax, making complex SPARQL queries more readable. It does a lot of work to make you more productive. This has lead to a common practice of always avoiding breaking changes and serving a versionless API. These are usually just tons of multi-gets. You can access the full capabilities of all your data from a single endpoint. It integrates tightly with Twitter's Thrift services, and in combination with the GraphQL API, gives them end-to-end types from database to the client. GraphQL supports nested data and other queries that are very hard to implement and consume with standard REST API resources (a. One that has nested types. I just want to store all the relations for the type in one map but I do not want and/or cant add this on database layer. This section is all about GraphQL type definitions and how they are used to define the overall GraphQL schema. GraphQL Content Delivery API is a more efficient alternative to the Content Delivery APIs. But not for nested field resolvers or data fetching. Learn how to optimize the performance of your queries. React and Relay. Create a new data fetcher. GraphQL is data-storage agnostic. All operations use the same syntax. This provides a very flexible way to derive GraphQL types based on your domain model - you can customize almost any aspect of the resulting GraphQL type (change names, add descriptions, add fields, deprecate fields, etc. Something like this:. Join us on June 15 in Berlin and see expert speakers from top GraphQL companies as well as the GraphQL creators Lee Byron and Nick Schrock. This library uses graphql-java under the hood for parsing of schema and queries, and managing the GraphQL state and context. All remaining. limit: Int: Optional. 8 (41 ratings) Course Ratings are calculated from individual students’ ratings and a variety of other signals, like age of rating and reliability, to ensure that they reflect course quality fairly and accurately. The object type is the most common type used in a schema and represents a group of fields. Also I wanted to use discriminator feature for two types of Tickets.