ContainsField

This reference topic applies to FQL v4. Go to this page for the latest FQL v10 reference topics.

ContainsField( field, in )
ContainsField( field, in )
contains_field( field, in )
ContainsField( field, in )

Description

The ContainsField function returns true if the specified field exists within the result of the in expression, or false otherwise.

ContainsField is useful when you need to distinguish between objects, arrays, or documents that contain a field and those that do not.

Parameters

Parameter Type Definition and Requirements

field

String

The name of a field.

in

Any

A value of any type.

Returns

A boolean value indicates whether field exists within in.

Examples

The following query returns true because the field a exists in the provided object:

result, err := client.Query(
	f.ContainsField(
		"a",
		f.Obj{
			"a": 1,
			"b": 2,
			"c": 3 }))

if err != nil {
	fmt.Fprintln(os.Stderr, err)
} else {
	fmt.Println(result)
}
true
client.query(
  q.ContainsField(
    'a',
    {
      a: 1,
      b: 2,
      c: 3,
    },
  )
)
.then((ret) => console.log(ret))
.catch((err) => console.error(
  'Error: [%s] %s: %s',
  err.name,
  err.message,
  err.errors()[0].description,
))
true
result = client.query(
  q.contains_field(
    "a",
    {
      "a": 1,
      "b": 2,
      "c": 3
    }
  )
)
print(result)
True
ContainsField(
  'a',
  {
    'a': 1,
    'b': 2,
    'c': 3,
  },
)
true
Query metrics:
  •    bytesIn:  58

  •   bytesOut:  17

  • computeOps:   1

  •    readOps:   0

  •   writeOps:   0

  •  readBytes:   0

  • writeBytes:   0

  •  queryTime: 5ms

  •    retries:   0

The following query returns false because the field f does not exist in the provided object:

result, err := client.Query(
	f.ContainsField(
		"f",
		f.Obj{
			"a": 1,
			"b": 2,
			"c": 3 }))

if err != nil {
	fmt.Fprintln(os.Stderr, err)
} else {
	fmt.Println(result)
}
false
client.query(
  q.ContainsField(
    'f',
    {
      a: 1,
      b: 2,
      c: 3,
    },
  )
)
.then((ret) => console.log(ret))
.catch((err) => console.error(
  'Error: [%s] %s: %s',
  err.name,
  err.message,
  err.errors()[0].description,
))
false
result = client.query(
  q.contains_field(
    "f",
    {
      "a": 1,
      "b": 2,
      "c": 3
    }
  )
)
print(result)
False
ContainsField(
  'f',
  {
    'a': 1,
    'b': 2,
    'c': 3,
  },
)
false
Query metrics:
  •    bytesIn:  58

  •   bytesOut:  18

  • computeOps:   1

  •    readOps:   0

  •   writeOps:   0

  •  readBytes:   0

  • writeBytes:   0

  •  queryTime: 6ms

  •    retries:   0

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