com.faunadb.client.types

Class Value

java.lang.Object

com.faunadb.client.query.Expr

com.faunadb.client.types.Value

Direct Known Subclasses:

Value.ArrayV, Value.BooleanV, Value.BytesV, Value.DateV, Value.DoubleV, Value.LongV, Value.NullV, Value.ObjectV, Value.QueryV, Value.RefV, Value.SetRefV, Value.StringV, Value.TimeV

public abstract class Value
extends Expr

Value represents query responses from FaunaDB. Instances of Value should be treated as opaque vales until converted to a native type. Available conversion methods are:

• to(Class)
• to(Codec)
• get(Field)
• getOptional(Field)
• collect(Field)
• asCollectionOf(Class)
• asMapOf(Class)

Value trees can be traversed using one of the following methods:

• at(int...)
• at(String...)

Examples:

Using the traversal API:

   Value result = client.query(getUserQuery).get();

   String name = result
     .at("data", "name")
     .to(String.class)
     .get();
 

Using a field extractor:

   Field<String> name = Field.at("data", "name").to(String.class);
   Value result = client.query(getUserQuery).get();
   String name = result.get(name);
 

See Also:

FaunaDB Value Types, Field, Codec

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Value.ArrayV Represents an array value in the FaunaDB query language.
static class	Value.BooleanV Represents a boolean value in the FaunaDB query language.
static class	Value.BytesV Represents a blob value in the FaunaDB query language.
static class	Value.DateV Represents a date value in the FaunaDB query language.
static class	Value.DoubleV Represents a double value in the FaunaDB query language.
static class	Value.LongV Represents a long value in the FaunaDB query language.
static class	Value.Native Builtin reference types.
static class	Value.NullV Represents a null value in the FaunaDB query language.
static class	Value.ObjectV Represents an Object value in the FaunaDB query language.
static class	Value.QueryV Represents a query value in the FaunaDB query language.
static class	Value.RefID The Value.RefV internal ID representation.
static class	Value.RefV A FaunaDB reference type.
static class	Value.SetRefV A FaunaDB set literal.
static class	Value.StringV Represents a string value in the FaunaDB query language.
static class	Value.TimeV Represents a timestamp value in the FaunaDB query language.

Method Summary

Modifier and Type	Method and Description
<T> Result<java.util.Collection<T>>	asCollectionOf(java.lang.Class<T> elementType) Attempts to convert the value to a Collection.
<T> Result<java.util.Map<java.lang.String,T>>	asMapOf(java.lang.Class<T> valueType) Attempts to convert the value to a Map.
Value	at(int... indexes) Assuming the underlying value is a collection, it traverses to a desired path.
Value	at(java.lang.String... keys) Assuming the underlying value is a key/value map, it traverses to a desired path.
<T> java.util.Collection<T>	collect(java.lang.Class<T> elementType) Attempts to convert the value to a Collection.
<T> java.util.List<T>	collect(Field<T> field) Assuming the underlying value is a collection, it collects the Field provided for all elements in the collection.
static <T> Result<Value>	from(T obj) Attempts to encode an object as a Value using the reflection Encoder.
<T> T	get(java.lang.Class<T> clazz) Attempts to decode the value using the reflection Decoder.
<T> T	get(Field<T> field) Extract a Field from the value.
java.util.Optional<Value>	getOptional() Converts this into an Optional.
<T> java.util.Optional<T>	getOptional(Field<T> field) Safely attempts to extract a Field from this value.
Value	orNull() Returns this value, or returns null if no value is present.
<T> Result<T>	to(java.lang.Class<T> clazz) Attempts to decode the value using the reflection Decoder.
<T> Result<T>	to(Codec<T> codec) Attempts to convert the value using the Codec passed.
<T> java.util.Map<java.lang.String,T>	toMap(java.lang.Class<T> valueType) Attempts to convert the value to a Map.

Methods inherited from class com.faunadb.client.query.Expr

toJson, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

to

public final <T> Result<T> to(Codec<T> codec)

Attempts to convert the value using the Codec passed.

Type Parameters:

T - the type to convert to

Parameters:

codec - codec function to attempt conversion

Returns:

the Result of the conversion

See Also:

Codec

to

public final <T> Result<T> to(java.lang.Class<T> clazz)

Attempts to decode the value using the reflection Decoder.

Type Parameters:

T - the type to convert to

Parameters:

clazz - a class type to convert

Returns:

the Result of the conversion

See Also:

Decoder

from

public static <T> Result<Value> from(T obj)

Attempts to encode an object as a Value using the reflection Encoder.

Type Parameters:

T - the type to convert from

Parameters:

obj - the object instance to encode

Returns:

the Result of the conversion

asMapOf

public final <T> Result<java.util.Map<java.lang.String,T>> asMapOf(java.lang.Class<T> valueType)

Attempts to convert the value to a Map.

Type Parameters:

T - the type of the values on Map

Parameters:

valueType - the type of the desired Map's values.

Returns:

a Result containing the resulting Map.

See Also:

Decoder, Types

toMap

public final <T> java.util.Map<java.lang.String,T> toMap(java.lang.Class<T> valueType)

Attempts to convert the value to a Map.

Type Parameters:

T - the type of the values in the Map

Parameters:

valueType - the type of the values in the Map

Returns:

a Map

See Also:

Decoder, Types

asCollectionOf

public final <T> Result<java.util.Collection<T>> asCollectionOf(java.lang.Class<T> elementType)

Attempts to convert the value to a Collection.

Type Parameters:

T - the type of the elements on the Collection

Parameters:

elementType - the type of the elements in the Collection.

Returns:

a Result containing the resulting Collection.

See Also:

Decoder, Types

collect

public final <T> java.util.Collection<T> collect(java.lang.Class<T> elementType)

Attempts to convert the value to a Collection.

Type Parameters:

T - the type of the elements in the Collection

Parameters:

elementType - the type of the elements in the Collection

Returns:

a new collection

See Also:

Decoder, Types

get

public final <T> T get(Field<T> field)

Extract a Field from the value.

Type Parameters:

T - the type of returned field

Parameters:

field - the Field to extract

Returns:

the resulting value of extracting the Field from this value

Throws:

java.lang.IllegalStateException - if Field does not exists on this value

See Also:

Field

get

public final <T> T get(java.lang.Class<T> clazz)

Attempts to decode the value using the reflection Decoder.

Type Parameters:

T - the type to convert to

Parameters:

clazz - a class type to convert

Returns:

the converted result

See Also:

Decoder

getOptional

public final <T> java.util.Optional<T> getOptional(Field<T> field)

Safely attempts to extract a Field from this value.

Type Parameters:

T - the type of returned field

Parameters:

field - Field to extract

Returns:

An Optional containing the resulting value, if the field extraction was successful. It returns Optional.empty(), otherwise.

See Also:

Field

getOptional

public java.util.Optional<Value> getOptional()

Converts this into an Optional.

Returns:

An Optional containing this value, if present.

orNull

public final Value orNull()

Returns this value, or returns null if no value is present.

Returns:

the value or null

collect

public final <T> java.util.List<T> collect(Field<T> field)

Assuming the underlying value is a collection, it collects the Field provided for all elements in the collection.

For example:

   Field<String> userName = Field.at("name").to(String.class);
   Value result = client.query(getAllUsersQuery).get();
   List<String> userNames = result.at("data").collect(userName);
 

Type Parameters:

T - the type of the elements in the resulting List

Parameters:

field - the Field to extract from each element in the underlying collection

Returns:

a List with the collected fields

See Also:

Field

at

public final Value at(java.lang.String... keys)

Assuming the underlying value is a key/value map, it traverses to a desired path.

For example:

   Value result = client.query(getUser).get();
   Value zipCode = result.at("data", "address", "zipCode");
 

Parameters:

keys - the object keys to traverse

Returns:

the Value under the path provided

at

public final Value at(int... indexes)

Assuming the underlying value is a collection, it traverses to a desired path.

For example:

   Value result = client.query(getAllUsers).get();
   Value firstUser = result.at("data").at(0);
 

Parameters:

indexes - the collection indexes to traverse

Returns:

the Value under the path provided