 Courses from Eve Porcello

GraphQL is gaining traction as one of the most popular ways to create an API. Regardless of which GraphQL implementation you pick, you’ll use the QL in GraphQL — the query language — to query data, change data with mutations, and listen for data changes with subscriptions.

You need to know the Query Language regardless of the server-side implementation.  In this course, we will learn the GraphQL query language by sending an assortment of GraphQL operations to an existing API. 

To start, we’ll learn how to write queries to obtain all the data needed for an app in one response. As the course progresses, we’ll use mutations to add and change data. To wrap up, we’ll investigate GraphQL subscriptions and realtime data. 

After the course, you’ll be ready to communicate with a GraphQL API regardless of server-side implementation using the GraphQL query language.

GraphQL is a query language for APIs and a runtime for fulfilling those queries with your existing data. GraphQL provides a complete and understandable description of the data in your API, gives clients the power to ask for exactly what they need and nothing more, makes it easier to evolve APIs over time, and enables powerful developer tools.

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GraphQL Query Language

GraphQL is a query language for your API that offers a new paradigm for delivering data to clients of all varieties. In this playlist, we’ll build a small fullstack application using GraphQL, Apollo Server, Apollo Client, and React, introducing a multitude of key GraphQL concepts along the way.

We’ll start by building the GraphQL API for a ski day counter application using Apollo Server. Then we’ll immediately send client queries to the GraphQL service to get the data. Later, we’ll incorporate mutations to change data, and we’ll integrate react-apollo to send queries and mutations from React components. Along the way, we’ll introduce useful schema design features like input types, enums, and custom scalars, and we’ll talk about client-side use cases like sending variables and caching. After watching these videos, you’ll be able to work on existing GraphQL projects or start your own with a full command of the fundamentals.

Bite-size video tutorials for badass web developers.

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Create Fullstack Applications with GraphQL and Apollo

Apollo provides a universal GraphQL API on top of your existing services, so you can build new application features fast without waiting on backend changes.

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Apollo Server is a GraphQL server that listens for incoming HTTP requests on a single endpoint.  In this lesson, we will stand up a simple GraphQL service that handles a query for total days skied during a season.

Create a GraphQL API with Apollo Server 2.0


One of the first major companies to launch a public GraphQL API was GitHub. In this lesson, we'll send queries to the [GitHub API](https://developer.github.com/v4/explorer/) to view our own data, and we'll get acquainted with some of the core features of the GraphQL query language.

Query the GitHub GraphQL API


With GraphQL, every field and nested object can have a set of arguments which can be used to request very specific data from a GraphQL API. In this lesson, we will pass arguments to the [GitHub API](https://developer.github.com/v4/explorer/) inline and as query variables.

Filter Data Based on Query Arguments with GraphQL

A GraphQL fragment encapsulates a collection of fields that can be included in queries. In this video, we'll look at how to create fragments on types to reduce the amount of typing that needs to occur as queries become more complex. We'll use the [GitHub API](https://developer.github.com/v4/explorer/) to test.

Reuse Query Fields with GraphQL Fragments

GraphQL is a query language for your API, which means that you can query or ask for the data that you need in one request, and you'll get one response as JSON. In this lesson, we'll introduce the key features of GraphQL.

WTF is GraphQL?

Queries get data from GraphQL services. If we want to change data, we will use GraphQL mutations. In this lesson, we’ll look at how to design GraphQL mutations to increment or decrement the number of ski days on record.

Change Data with GraphQL Mutations

Using the GraphQL Schema Definition Language, we can define types that reflect all of the objects available on our API. In this lesson, we will create a SkiDay type and return a list of SkiDay objects with an allDays query. We will also create an enum, which describes a restricted list of allowed values for a particular field.

Create a GraphQL Object Type and Query a List of Objects

If you want to be able to parse and serialize custom scalar types sent as arguments, you’ll add the parseValue and parseLiteral functions to the custom scalar constructor. In this video, we’ll take a closer look at these functions and how they can be used to transform data passed by the client.


Parsing GraphQL Mutation Arguments with Custom Scalars

The addDay mutation should add details about each ski day. In this lesson, we’ll capture argument values from the GraphQL mutation and use this to change the ski day array.

Add Data to an Array with a GraphQL Mutation

Resolvers are functions that return data for specific fields. In this lesson, we’ll take a look at how to throw errors within resolvers if the data passed as arguments is incorrect or insufficient.

Incorporate Custom Error Handling within GraphQL Resolvers

GraphQL has five built-in scalar types that can be returned from a field: Int, Float, Boolean, String, and ID. It is also possible to create and validate your own custom scalar if you want to return a single value or leaf instead of an object from a field. In this lesson, we’ll build a custom scalar type to handle parsing and serializing dates.

Define a Custom Scalar Type for a GraphQL API

When passing arguments to a GraphQL mutation, you can send them inline, or you can wrap them in an input type. In this lesson, we’ll create an input type for the addDay mutation which will allow us to pass an entire object as an argument.

Wrap GraphQL Mutation Arguments with a GraphQL Input Type

GraphQL mutations are used to change data and can be also used to delete data. In this lesson, we’ll make changes to the removeDay mutation to delete a day from the ski days array by id. Additionally, we’ll return a custom type when we send the mutation.

Remove Items from an Array with a GraphQL Mutation

The GraphQL Playground is an IDE for interacting with a GraphQL API. GraphQL APIs have a single endpoint. Queries are used to request specific data from that endpoint. In this lesson, we will send a query to obtain the total number of pets registered at the [Pet Library](https://pet-library.moonhighway.com).

Send a Query with GraphQL Playground

Now that we understand how to write a simple query to check a total value, we're going to write a query to return a list of pet objects. Along the way, we'll learn a bit more about the GraphQL query language, tackling vocabulary like selection sets and fields. All of the queries are sent to the [Pet Library API](https://pet-library.moonhighway.com).

Query a List of Objects with GraphQL

In the GraphQL Query Language, an enum or enumeration type is a restricted list of values for a particular field. We'll query an enum field, category, in this lesson to find out the different pet categories. This lesson also takes a look at the GraphQL schema for the API.

To follow along with these queries, go to the [Pet Library GraphQL Playground](https://pet-library.moonhighway.com).


Query an Enumeration Type with GraphQL

In addition to returning lists or scalar values, it’s possible to return GraphQL objects from fields. In this lesson, we’ll take a closer look at the `Photo` type and how it can be used to store more complex data types.
	
To follow along with these queries, go to the [Pet Library GraphQL Playground](https://pet-library.moonhighway.com).


Send a Nested GraphQL Query

Some GraphQL queries will have arguments. Arguments can be used to send additional options about the data set that you wish to receive. They may be used to specify sorting preferences, limit the number of records returned, or filter data. In this lesson, we will filter a list of pets by status.
	
To follow along with these queries, go to the [Pet Library GraphQL Playground](https://pet-library.moonhighway.com).


Filter a GraphQL Query Result Using Arguments

When writing GraphQL queries, you may want to query the same field with different arguments. In this lesson, we’ll show the problem with naming collisions in GraphQL queries and how they can be solved with aliases.

To follow along with these queries, go to the [Pet Library GraphQL Playground](https://pet-library.moonhighway.com).


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