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.
Syntax Examples (using default values):
  • query title($name: string = "Bauman") { ... }
  • query title($age: int = "95") { ... }
  • query title($uids: string = "0x1") { ... }
  • query title($uids: string = "[0x1, 0x2, 0x3]") { ... }. The value of the variable is a quoted array.
Variables can be defined and used in queries which helps in query reuse and avoids costly string building in clients at runtime by passing a separate variable map. A variable starts with a $ symbol. For HTTP requests with GraphQL Variables, we must use Content-Type: application/json header and pass data with a JSON object containing query and variables. 
curl -H "Content-Type: application/json" localhost:8080/query -XPOST -d $'{
  "query": "query test($a: string) { test(func: eq(name, $a)) { \n uid \n name \n } }",
  "variables": { "$a": "Alice" }
}' | python -m json.tool | less

$a: "5",
$b: "10",
$name: "Steven Spielberg"

query {
  test($a: int, $b: int, $name: string) {
    me(func: allofterms(name@en, $name)) {
      name@en
      director.film (first: $a, offset: $b) {
        name @en genre(first: $a) { name@en }
      }
    }
  }
}
  • Variables can have default values. In the example below, $a has a default value of 2. Since the value for $a isn’t provided in the variable map, $a takes on the default value.
  • Variables whose type is suffixed with a ! can’t have a default value but must have a value as part of the variables map.
  • The value of the variable must be parsable to the given type, if not, an error is thrown.
  • The variable types that are supported as of now are: int, float, bool and string.
  • Any variable that’s being used must be declared in the named query clause in the beginning.
$b: "10",
$name: "Steven Spielberg"

query {
  test($a: int = 2, $b: int!, $name: string) {
    me(func: allofterms(name@en, $name)) {
      director.film (first: $a, offset: $b) { genre(first: $a) { name@en } }
    }
  }
}
You can also use array with GraphQL Variables. 
$b: "10",
$aName: "Steven Spielberg",
$bName: "Quentin Tarantino"

query {
  test($a: int = 2, $b: int!, $aName: string, $bName: string) {
    me(func: eq(name@en, [$aName, $bName])) {
      director.film (first: $a, offset: $b) { genre(first: $a) { name@en } }
    }
  }
}
We also support variable substitution in facets. 
$name: "Alice",
$IsClose: "true"

query {
  test($name: string = "Alice", $IsClose: string = "true") {
    data(func: eq(name, $name)) {
      friend @facets(eq(close, $IsClose)) { name }
      colleague : friend @facets(eq(close, false)) { name }
    }
  }
}
If you want to input a list of UIDs as a GraphQL variable value, you can have the variable as string type and have the value surrounded by square brackets like ["13", "14"].