GraphQL Fundamentals

© 2021 GraphQL, Inc. Page | 1
GraphQL Fundamentals

© 2021 GraphQL.
.
Page | 2
Senior Software Engineer at BORN Group
Virbhadra S. Ankalkote

© 2021 GraphQL Page | 3
Agenda

Agenda
{
graphql:{
what
who
why
how
}
}

What ?

“GraphQL is a query language
for APIs, and a runtime for
fulﬁlling those queries with
existing data ”

Who ?

“In 2012, Facebook develop the
GraphQL technology for their
native mobile app”
.

.
2012 2015 2017..2018...2020
Development Started Open Source Evolving Specification.
Timeline

Why?

Application Programming Interface (API)

REST Flow

Principles of REST API Design

GraphQL Flow

Browser Tools

GraphQL Playground

How?

Limitations

Reading Data

Writing Data ( Mutation )

GraphQL Variables

• In GraphQL, you can use variables to reuse the same query/mutations written by
the client, with different arguments.
• When we start working with variables, we need to do three things:
– Replace the static value in the query with $variableName
– Declare $variableName as one of the variables accepted by the query
– Pass variableName: value in the separate, transport-speciﬁc (usually JSON)
variables dictionary

GraphQL Fragments

• A GraphQL fragment is a piece of logic that a client can share between multiple
queries and mutations.
• In GraphQL, you often need to query for the same data ﬁelds in different queries.
• By reusing this code, we can be more efﬁcient with our time and reuse these piece
of queries

Pain Points of GraphQL

Almost impossible to solve
● Query In Indefinite Depth
– GraphQL cannot query in indefinite depth, so if you have a tree and want to
return a branch without knowing the depth, you’ll have to do some
pagination
● Specific Response Structure
– In GraphQL the response matches the shape of the query, so if you need to
respond in a very specific structure, you'll have to add a transformation layer
to reshape the response.

Hard to solve
● Cache at Network Level
– Because of the commonly way GraphQL is used over HTTP (A POST in a
single endpoint), cache at network level becomes hard. A way to solve it is to
use Persisted Queries.
● Handling File Upload
– There is nothing about file upload in the GraphQL specification and
mutations doesn’t accept files in the arguments. To solve it you can upload
files using other kind of APIs (like REST) and pass the URL of the uploaded file
to the GraphQL mutation, or inject the file in the execution context, so you’ll
have the file inside the resolver functions.

Questions ?

Thank You

GraphQL Fundamentals

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