We’re overhauling Dgraph’s docs to make them clearer and more approachable. If
you notice any issues during this transition or have suggestions, please
let us know.
Let’s start with listing down the entities that are involved in a basic to do
app.
Equivalent GraphQL schema for this graph is be as follow:
type Task {
...
}
type User {
...
}
What are the fields that these two simple entities contain?
There is a title and a status to check if it was completed or not in the Task
type. Then the User
type has a username (unique identifier), name and the
tasks.
So each user can have many tasks.
’ * ’ signifies one-to-many relationship
Now let’s add @id
directive to username
which makes it the unique key & also
add @hasInverse
directive to enable the relationship between tasks and user.
We represent that in the GraphQL schema shown below:
type Task {
id: ID!
title: String!
completed: Boolean!
user: User!
}
type User {
username: String! @id
name: String
tasks: [Task] @hasInverse(field: user)
}
Save the content in a file schema.graphql
.
Running
Before we begin, make sure that you have
Docker installed on your machine.
Let’s begin by starting Dgraph standalone by running the command below:
docker run -it -p 8080:8080 dgraph/standalone:%VERSION_HERE
Let’s load up the GraphQL schema file to Dgraph:
curl -X POST localhost:8080/admin/schema --data-binary '@schema.graphql'
You can access that GraphQL endpoint with any of the great GraphQL developer
tools. Good choices include GraphQL Playground, Insomnia, GraphiQL and Altair.
Set up any of them and point it at http://localhost:8080/graphql
. If you know
lots about GraphQL, you might want to explore the schema, queries and mutations
that were generated from the schema.
Mutating data
Let’s add a user and some to dos in our To Do app.
mutation {
addUser(
input: [
{
username: "alice@dgraph.io"
name: "Alice"
tasks: [
{ title: "Avoid touching your face", completed: false }
{ title: "Stay safe", completed: false }
{ title: "Avoid crowd", completed: true }
{ title: "Wash your hands often", completed: true }
]
}
]
) {
user {
username
name
tasks {
id
title
}
}
}
}
Querying data
Let’s fetch the to dos to list in our To Do app:
query {
queryTask {
id
title
completed
user {
username
}
}
}
Running this query should return JSON response as shown below:
{
"data": {
"queryTask": [
{
"id": "0x3",
"title": "Avoid touching your face",
"completed": false,
"user": {
"username": "alice@dgraph.io"
}
},
{
"id": "0x4",
"title": "Stay safe",
"completed": false,
"user": {
"username": "alice@dgraph.io"
}
},
{
"id": "0x5",
"title": "Avoid crowd",
"completed": true,
"user": {
"username": "alice@dgraph.io"
}
},
{
"id": "0x6",
"title": "Wash your hands often",
"completed": true,
"user": {
"username": "alice@dgraph.io"
}
}
]
}
}
Querying data with filters
Before we get into querying data with filters, we’re required to define search
indexes to the specific fields.
Let’s say we want to run a query on the completed
field, for which we add
@search
directive to the field, as shown in the schema below:
type Task {
id: ID!
title: String!
completed: Boolean! @search
user: User!
}
The @search
directive is added to support the native search indexes of
Dgraph.
Resubmit the updated schema -
curl -X POST localhost:8080/admin/schema --data-binary '@schema.graphql'
Now, let’s fetch all to dos which are completed:
query {
queryTask(filter: { completed: true }) {
title
completed
}
}
Next, let’s say we want to run a query on the title
field, for which we add
another @search
directive to the field, as shown in the schema below:
type Task {
id: ID!
title: String! @search(by: [fulltext])
completed: Boolean! @search
user: User!
}
The fulltext
search index provides the advanced search capability to perform
equality comparison as well as matching with language-specific stemming and
stopwords.
Resubmit the updated schema -
curl -X POST localhost:8080/admin/schema --data-binary '@schema.graphql'
Now, let’s try to fetch to dos whose title has the word “avoid”:
query {
queryTask(filter: { title: { alloftext: "avoid" } }) {
id
title
completed
}
}