Search and Filtering

Queries generated for a GraphQL type allow you to generate a single list of objects for a type. You can also query a list of objects using GraphQL.

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.

Queries generated for a GraphQL type allow you to generate a single list of objects for a type.

Get a single object

Fetch the title, text and datePublished for a post with id 0x1.

query {
  getPost(id: "0x1") {
    title
    text
    datePublished
  }
}

Fetching nested linked objects, while using get queries is also easy. For example, this is how you would fetch the authors for a post and their friends.

query {
  getPost(id: "0x1") {
    id
    title
    text
    datePublished
    author {
      name
      friends {
        name
      }
    }
  }
}

While fetching nested linked objects, you can also apply a filter on them.

For example, the following query fetches the author with the id 0x1 and their posts about GraphQL.

query {
  getAuthor(id: "0x1") {
    name
    posts(filter: { title: { allofterms: "GraphQL" } }) {
      title
      text
      datePublished
    }
  }
}

If your type has a field with the @id directive applied to it, you can also fetch objects using that.

For example, given the following schema, the query below fetches a user’s name and age by userID (which has the @id directive):

Schema:

type User {
  userID: String! @id
  name: String!
  age: String
}

Query:

query {
  getUser(userID: "0x2") {
    name
    age
  }
}

Query a list of objects

You can query a list of objects using GraphQL. For example, the following query fetches the title, text and datePublished for all posts:

query {
  queryPost {
    id
    title
    text
    datePublished
  }
}

The following example query fetches a list of posts by their post id:

query {
  queryPost(filter: { id: ["0x1", "0x2", "0x3", "0x4"] }) {
    id
    title
    text
    datePublished
  }
}

Query that filters objects by predicate

Before filtering an object by a predicate, you need to add a @search directive to the field that’s used to filter the results.

For example, if you wanted to query events between two dates, or events that fall within a certain radius of a point, you could have an Event schema, as follows:

type Event {
  id: ID!
  date: DateTime! @search
  location: Point @search
}

The search directive would let you filter events that fall within a date range, as follows:

query {
  queryEvent(
    filter: { date: { between: { min: "2020-01-01", max: "2020-02-01" } } }
  ) {
    id
  }
}

You can also filter events that have a location near a certain point with the following query:

query {
  queryEvent(
    filter: {
      location: {
        near: {
          coordinate: { latitude: 37.771935, longitude: -122.469829 }
          distance: 1000
        }
      }
    }
  ) {
    id
  }
}

You can also use connectors such as the and keyword to show results with multiple filters applied. In the query below, we fetch posts that have GraphQL in their title and have a score > 100.

This example assumes that the Post type has a @search directive applied to the title field and the score field.

query {
  queryPost(
    filter: { title: { anyofterms: "GraphQL" }, and: { score: { gt: 100 } } }
  ) {
    id
    title
    text
    datePublished
  }
}

Filter a query for a list of objects

You can also filter nested objects while querying for a list of objects.

For example, the following query fetches all of the authors whose name contains Lee and with their completed posts that have a score greater than 10:

query {
  queryAuthor(filter: { name: { anyofterms: "Lee" } }) {
    name
    posts(filter: { score: { gt: 10 }, and: { completed: true } }) {
      title
      text
      datePublished
    }
  }
}

Filter a query for a range of objects with between

You can filter query results within an inclusive range of indexed and typed scalar values using the between keyword.

This keyword is also supported for DQL. To learn more, see DQL Functions: between.

For example, you might start with the following example schema used to track students at a school:

Schema:

type Student {
  age: Int @search
  name: String @search(by: [exact])
}

Using the between filter, you could fetch records for students who are between 10 and 20 years of age:

Query:

queryStudent(filter: {age: between: {min: 10, max: 20}}){
    age
    name
}

You could also use this filter to fetch records for students whose names fall alphabetically between ba and hz:

Query:

queryStudent(filter: {name: between: {min: "ba", max: "hz"}}){
    age
    name
}

Filter to match specified field values with in

You can filter query results to find objects with one or more specified values using the in keyword. This keyword can find matches for fields with the @id directive applied. The in filter is supported for all data types such as string, enum, Int, Int64, Float, and DateTime.

For example, let’s say that your schema defines a State type that has the @id directive applied to the code field:

type State {
  code: String! @id
  name: String!
  capital: String
}

Using the in keyword, you can query for a list of states that have the postal code WA or VA using the following query:

query {
  queryState(filter: { code: { in: ["WA", "VA"] } }) {
    code
    name
  }
}

Filter for objects with specified non-null fields using has

You can filter queries to find objects with a non-null value in a specified field using the has keyword. The has keyword can only check whether a field returns a non-null value, not for specific field values.

For example, your schema might define a Student type that has basic information about each student such as their ID number, age, name, and email address:

type Student {
  tid: ID!
  age: Int!
  name: String
  email: String
}

To find those students who have a non-null name, run the following query:

queryStudent(filter: { has : name } ){
   tid
   age
   name
}

You can also specify a list of fields, like the following:

queryStudent(filter: { has : [name, email] } ){
   tid
   age
   name
   email
}

This would return Student objects where both name and email fields are non-null.