Reactive GraphQL Masterclass For Java Spring Boot Developers

Learn how non-null arguments enforce required fields in GraphQL schemas, using exclamation marks to demand input and showing client-side validation through strong typing in GraphQL for Java Spring Boot developers.

Restructure the project into section zero one and lecture zero one to revisit graphical concepts, moving the graphical controller and GraphQL schema under the new structure and validating with tests.

Create a custom GraphQL object type for customers, define a query API to fetch all customers, fetch by id, and filter by name with non-null guarantees.

Demo shows configuring the GraphQL schema, scanning packages, and querying customers by selecting fields like name and city to reduce latency, including id-based lookups and name contains filters.

Build an order service for nested objects by modeling customer orders with a data transfer object and exposing a reactive method that returns a flux of orders by customer name.

Learn how fields resolve in GraphQL by using schema mapping and parent objects to access customer and orders, enabling GraphQL to fetch data only when requested.

Explain the N+1 problem in GraphQL and demonstrate a batch mapping fix that fetches all customers in one call and retrieves their orders in a single batch.

Explore GraphQL scalar types, enums, and schemas. Learn query, mutation, and subscription mappings with parallel reactive resolution and batch mapping to reduce latency and avoid the plus one problem.

Demonstrates using field aliases to call the same GraphQL endpoint with different arguments, enabling multiple queries (by id and by age range) in a single request.

Learn how fragments create reusable units in GraphQL to avoid repeating fields. Define a customer details fragment for id, name, age, and city, and apply it with the spread operator.

Explore how operation names in GraphQL enable production monitoring, logging, and caching, while allowing multiple queries in a single request for targeted performance insights.

Master variable binding in a reactive GraphQL query by declaring three age-range filters for kids, adults, and seniors, and pass corresponding ranges to refine results.

Explore how GraphQL directives like @include and @skip control field resolution at runtime, using boolean conditions and variables to selectively fetch kids or adults data.

Develop and set up a simple project and playground to implement a custom data feature, explore GraphQL's nested object fetching, and prepare the corresponding schema.

Configure runtime wiring for a GraphQL Spring Boot app by implementing a data feature, wiring the query type and customers field, and returning a flux of customers with orders.

Explore the field glob pattern in GraphQL, construct a nested level one to five schema, and use selection sets with contains and double star checks to navigate the hierarchy.

Design a GraphQL interface with common fields like id, description, and price that fruit, electronics, and book types implement with category-specific fields such as expiry date and brand.

Demonstrates how a GraphQL interface models real-life reservations by defining a reservation interface with hotel, car, and flight implementations, exposing common fields and aliasing the type name for unified responses.

Design a GraphQL union named result to return fruit, electronics, or book types (and potentially stock or location) for a search keyword, clarifying the schema design.

Implement operation caching for GraphQL in Spring Boot by parsing and validating once, then caching the pre parsed document entry for subsequent requests using a concurrent map and computeIfAbsent.

Explore reactive GraphQL data fetching in Spring Boot, covering the data fetching environment, selection sets, field lookahead, runtime wiring, interfaces and unions, and LRU/caffeine caching to prevent memory errors.

Reuse the existing project and add three key dependencies for database connectivity, update the pom.xml, reload Maven, then create GraphQL directories for lecture 13 and begin with schema creation.

Fetch only the requested fields from upstream by using GraphQL to aggregate multiple microservice calls and return just the selected id and name from customer, reducing latency and bandwidth.

Publish customer events using subscription mapping in GraphQL to stream updates via server-sent events, enabling subscribers to receive real-time notifications such as customer created or deleted.

Learn to build a reactive subscription service in Spring by defining a customer event data model, an action enum, and a Flux multicast stream to emit and subscribe to events.

Set up the project by reusing the lecture 13 credit application, create a new lecture 15 package, copy and paste existing code, and prepare the schema for integration.

Explore how GraphQL handles runtime exceptions by throwing errors in the controller and observe data and errors in responses, with path, line, and column details.

Develop a generic application exception with error type, message, and optional extensions, then define application errors and map them via an exception resolver to meaningful responses.

Develop a Spring configuration type resolver to handle a union type between customer data and not found responses, then create and reuse a fragment for consistent GraphQL queries.

Learn how to secure GraphQL using spring web flex security or spring web security, with guidance on annotations on service methods that fetch GraphQL responses.

Create a self-contained GraphQL client in a Spring Boot project, wiring a web client, and sending raw queries via execute to fetch customer data from the customer service.

Demonstrates storing GraphQL queries as files in resources, loading them at runtime, and sending the query to fetch a customer by ID using variables and a fragment.

Master GraphQL by building a single query with an alias to fetch multiple fields, testing with hard-coded values and multiple arguments, and decoding and printing response via a graphical tool.

Learn to use the execute method to fetch the whole object, apply the map method, and return a multi customer assignment entity.

The lecture shows handling GraphQL client errors in a reactive pipeline by returning a default data object or a generic error response to the service layer.

Explore how to implement a get all customers query in a reactive GraphQL client for Java Spring Boot, using a CRUD operation, aliasing fields, and returning a customer data list.

This lecture demonstrates creating a customer via GraphQL, showing how to avoid sending an id field and two fixes: use a dedicated customer input type or configure not-null serialization.

Explore how to execute GraphQL operations with client strategies, including string queries and documents, variables and operation names, error handling, field serialization, and web socket subscriptions.

Set up an integration test project for a GraphQL operation in Spring Boot, using the source/test/java path and a test client, with http GraphQL test configuration via Spring injection.

Perform an integration test using lecture 14 to cover CRUD operations and subscriptions, with a test property source to override properties and validate the query response.

Set up and run a Spring integration test by organizing test resources under source test resources, reading the crud operations file, and validating a get by id response.

Develop and validate a GraphQL error handling test for a create operation with age restrictions, asserting a single graphical error and a bad request response for under-18 input.

Create a Spring Boot integration test for GraphQL subscriptions using HTTP and WebSocket clients, configuring a WS endpoint to observe customer events with id and action.

Set up a reactive GraphQL movie app by creating a Spring Boot project with Maven or Gradle, selecting Java 17, and adding GraphQL, WebFlux, and Lombok.

Design GraphQL schemas by defining user profile and movie detail queries, genre-based movie lists, and add-to-watch-list mutations with corresponding response types and status enums, plus update profile mutations.