StreamingJsonBuilder (Groovy 4.0.0)

groovy.json.StreamingJsonBuilder

public class StreamingJsonBuilder
extends GroovyObjectSupport

A builder for creating JSON payloads.

This builder supports the usual builder syntax made of nested method calls and closures, but also some specific aspects of JSON data structures, such as list of values, etc. Please make sure to have a look at the various methods provided by this builder to be able to learn about the various possibilities of usage.

Unlike the JsonBuilder class which creates a data structure in memory, which is handy in those situations where you want to alter the structure programatically before output, the StreamingJsonBuilder streams to a writer directly without any memory data structure. So if you don't need to modify the structure, and want a more memory-efficient approach, please use the StreamingJsonBuilder.

Example:

     new StringWriter().with { w ->
         def builder = new groovy.json.StreamingJsonBuilder(w)
         builder.people {
             person {
                 firstName 'Tim'
                 lastName 'Yates'
                 // Named arguments are valid values for objects too
                 address(
                     city: 'Manchester',
                     country: 'UK',
                     zip: 'M1 2AB',
                 )
                 living true
                 eyes 'left', 'right'
             }
         }

         assert w.toString() == '{"people":{"person":{"firstName":"Tim","lastName":"Yates","address":{"city":"Manchester","country":"UK","zip":"M1 2AB"},"living":true,"eyes":["left","right"]}}}'
    }

Since:: 1.8.1

Nested Class Summary

Nested classes
Modifiers	Name	Description
`static class`	`StreamingJsonBuilder.StreamingJsonDelegate`	The delegate used when invoking closures

Constructor Summary

Constructors
Constructor and description
`StreamingJsonBuilder(Writer writer)` Instantiates a JSON builder.
`StreamingJsonBuilder(Writer writer, JsonGenerator generator)` Instantiates a JSON builder with the given generator.
`StreamingJsonBuilder(Writer writer, Object content)` Instantiates a JSON builder, possibly with some existing data structure.
`StreamingJsonBuilder(Writer writer, Object content, JsonGenerator generator)` Instantiates a JSON builder, possibly with some existing data structure and the given generator.

Methods Summary

Methods
Type Params	Return Type	Name and description
	`public Object`	`call(Map m)` Named arguments can be passed to the JSON builder instance to create a root JSON object
	`public void`	`call(String name)` The empty args call will create a key whose value will be an empty JSON object: new StringWriter().with { w `->` def json = new groovy.json.StreamingJsonBuilder(w) json.person()
	`public Object`	`call(List l)` A list of elements as arguments to the JSON builder creates a root JSON array
	`public Object`	`call(Object args)` Varargs elements as arguments to the JSON builder create a root JSON array
	`public Object`	`call(Iterable coll, Closure c)` A collection and closure passed to a JSON builder will create a root JSON array applying the closure to each object in the collection
	`public Object`	`call(Collection coll, Closure c)` Delegates to call(Iterable, Closure)
	`public Object`	`call(Closure c)` A closure passed to a JSON builder will create a root JSON object
	`public void`	`call(String name, Closure c)` A name and a closure passed to a JSON builder will create a key with a JSON object
	`public void`	`call(String name, Iterable coll, Closure c)` A name, a collection and closure passed to a JSON builder will create a root JSON array applying the closure to each object in the collection
	`public void`	`call(String name, Collection coll, Closure c)` Delegates to call(String, Iterable, Closure)
	`public void`	`call(String name, Map map, Closure callable)` If you use named arguments and a closure as last argument, the key/value pairs of the map (as named arguments) and the key/value pairs represented in the closure will be merged together — the closure properties overriding the map key/values in case the same key is used.
	`public Object`	`invokeMethod(String name, Object args)` A method call on the JSON builder instance will create a root object with only one key whose name is the name of the method being called.

Inherited Methods Summary

Inherited Methods
Methods inherited from class	Name
`class GroovyObjectSupport`	`getMetaClass, setMetaClass`

- Constructor Detail
  - public StreamingJsonBuilder(Writer writer)
    
    Instantiates a JSON builder.
    Parameters:
    writer - A writer to which Json will be written
  - public StreamingJsonBuilder(Writer writer, JsonGenerator generator)
    
    Instantiates a JSON builder with the given generator.
    Parameters:
    writer - A writer to which Json will be written
    generator - used to generate the output
    Since:
    2.5.0
  - public StreamingJsonBuilder(Writer writer, Object content)
    
    Instantiates a JSON builder, possibly with some existing data structure.
    throws:
    IOException
    
    Parameters:
    writer - A writer to which Json will be written
    content - a pre-existing data structure, default to null
  - public StreamingJsonBuilder(Writer writer, Object content, JsonGenerator generator)
    
    Instantiates a JSON builder, possibly with some existing data structure and the given generator.
    throws:
    IOException
    
    Parameters:
    writer - A writer to which Json will be written
    content - a pre-existing data structure, default to null
    generator - used to generate the output
    Since:
    2.5.0
- Method Detail
  - public Object call(Map m)
    
    Named arguments can be passed to the JSON builder instance to create a root JSON object
    Example:
```
 new StringWriter().with { w ->
   def json = new groovy.json.StreamingJsonBuilder(w)
   json name: "Tim", age: 31

   assert w.toString() == '{"name":"Tim","age":31}'
 }
 
```
    Parameters:
    m - a map of key / value pairs
    Returns:
    a map of key / value pairs
  - public void call(String name)
    
    The empty args call will create a key whose value will be an empty JSON object:
```
 new StringWriter().with { w ->
     def json = new groovy.json.StreamingJsonBuilder(w)
     json.person()

     assert w.toString() == '{"person":{}}'
 }
 
```
    throws:
    IOException
    
    Parameters:
    name - The name of the empty object to create
  - public Object call(List l)
    
    A list of elements as arguments to the JSON builder creates a root JSON array
    Example:
```
 new StringWriter().with { w ->
   def json = new groovy.json.StreamingJsonBuilder(w)
   def result = json([1, 2, 3])

   assert result == [ 1, 2, 3 ]
   assert w.toString() == "[1,2,3]"
 }
 
```
    Parameters:
    l - a list of values
    Returns:
    a list of values
  - public Object call(Object args)
    
    Varargs elements as arguments to the JSON builder create a root JSON array
    Example:
```
 new StringWriter().with { w ->
   def json = new groovy.json.StreamingJsonBuilder(w)
   def result = json 1, 2, 3

   assert result instanceof List
   assert w.toString() == "[1,2,3]"
 }
 
```
    Parameters:
    args - an array of values
    Returns:
    a list of values
  - public Object call(Iterable coll, @DelegatesTo(value = StreamingJsonDelegate.class, strategy = Closure.DELEGATE_FIRST) Closure c)
    
    A collection and closure passed to a JSON builder will create a root JSON array applying the closure to each object in the collection
    Example:
```
 class Author {
      String name
 }
 def authors = [new Author (name: "Guillaume"), new Author (name: "Jochen"), new Author (name: "Paul")]

 new StringWriter().with { w ->
     def json = new groovy.json.StreamingJsonBuilder(w)
     json authors, { Author author ->
         name author.name
     }

     assert w.toString() == '[{"name":"Guillaume"},{"name":"Jochen"},{"name":"Paul"}]'
 }
 
```
    Parameters:
    coll - a collection
    c - a closure used to convert the objects of coll
  - public Object call(Collection coll, @DelegatesTo(value = StreamingJsonDelegate.class, strategy = Closure.DELEGATE_FIRST) Closure c)
    
    Delegates to call(Iterable, Closure)
  - public Object call(@DelegatesTo(value = StreamingJsonDelegate.class, strategy = Closure.DELEGATE_FIRST) Closure c)
    
    A closure passed to a JSON builder will create a root JSON object
    Example:
```
 new StringWriter().with { w ->
   def json = new groovy.json.StreamingJsonBuilder(w)
   json {
      name "Tim"
      age 39
   }

   assert w.toString() == '{"name":"Tim","age":39}'
 }
 
```
    Parameters:
    c - a closure whose method call statements represent key / values of a JSON object
  - public void call(String name, @DelegatesTo(value = StreamingJsonDelegate.class, strategy = Closure.DELEGATE_FIRST) Closure c)
    
    A name and a closure passed to a JSON builder will create a key with a JSON object
    Example:
```
 new StringWriter().with { w ->
   def json = new groovy.json.StreamingJsonBuilder(w)
   json.person {
      name "Tim"
      age 39
   }

   assert w.toString() == '{"person":{"name":"Tim","age":39}}'
 }
 
```
    Parameters:
    name - The key for the JSON object
    c - a closure whose method call statements represent key / values of a JSON object
  - public void call(String name, Iterable coll, @DelegatesTo(value = StreamingJsonDelegate.class, strategy = Closure.DELEGATE_FIRST) Closure c)
    
    A name, a collection and closure passed to a JSON builder will create a root JSON array applying the closure to each object in the collection
    Example:
```
 class Author {
      String name
 }
 def authors = [new Author (name: "Guillaume"), new Author (name: "Jochen"), new Author (name: "Paul")]

 new StringWriter().with { w ->
     def json = new groovy.json.StreamingJsonBuilder(w)
     json.people authors, { Author author ->
         name author.name
     }

     assert w.toString() == '{"people":[{"name":"Guillaume"},{"name":"Jochen"},{"name":"Paul"}]}'
 }
 
```
    Parameters:
    coll - a collection
    c - a closure used to convert the objects of coll
  - public void call(String name, Collection coll, @DelegatesTo(value = StreamingJsonDelegate.class, strategy = Closure.DELEGATE_FIRST) Closure c)
    
    Delegates to call(String, Iterable, Closure)
  - public void call(String name, Map map, @DelegatesTo(value = StreamingJsonDelegate.class, strategy = Closure.DELEGATE_FIRST) Closure callable)
    
    If you use named arguments and a closure as last argument, the key/value pairs of the map (as named arguments) and the key/value pairs represented in the closure will be merged together — the closure properties overriding the map key/values in case the same key is used.
```
 new StringWriter().with { w ->
     def json = new groovy.json.StreamingJsonBuilder(w)
     json.person(name: "Tim", age: 35) { town "Manchester" }

     assert w.toString() == '{"person":{"name":"Tim","age":35,"town":"Manchester"}}'
 }
 
```
    throws:
    IOException
    
    Parameters:
    name - The name of the JSON object
    map - The attributes of the JSON object
    callable - Additional attributes of the JSON object represented by the closure
  - @Override public Object invokeMethod(String name, Object args)
    
    A method call on the JSON builder instance will create a root object with only one key whose name is the name of the method being called. This method takes as arguments:
    - a closure
    - a map (ie. named arguments)
    - a map and a closure
    - or no argument at all
    Example with a classical builder-style:
```
 new StringWriter().with { w ->
     def json = new groovy.json.StreamingJsonBuilder(w)
     json.person {
         name "Tim"
          age 28
     }

     assert w.toString() == '{"person":{"name":"Tim","age":28}}'
 }
 
```
    Or alternatively with a method call taking named arguments:
```
 new StringWriter().with { w ->
     def json = new groovy.json.StreamingJsonBuilder(w)
     json.person name: "Tim", age: 32

     assert w.toString() == '{"person":{"name":"Tim","age":32}}'
 }
 
```
    If you use named arguments and a closure as last argument, the key/value pairs of the map (as named arguments) and the key/value pairs represented in the closure will be merged together — the closure properties overriding the map key/values in case the same key is used.
```
 new StringWriter().with { w ->
     def json = new groovy.json.StreamingJsonBuilder(w)
     json.person(name: "Tim", age: 35) { town "Manchester" }

     assert w.toString() == '{"person":{"name":"Tim","age":35,"town":"Manchester"}}'
 }
 
```
    The empty args call will create a key whose value will be an empty JSON object:
```
 new StringWriter().with { w ->
     def json = new groovy.json.StreamingJsonBuilder(w)
     json.person()

     assert w.toString() == '{"person":{}}'
 }
 
```
    Parameters:
    name - the single key
    args - the value associated with the key

Summary:
Nested
Constructor
Method

| Detail:
Constructor
Method

[Java] Class StreamingJsonBuilder

Nested Class Summary

Constructor Summary

Methods Summary

Inherited Methods Summary

Constructor Detail

public StreamingJsonBuilder(Writer writer)

public StreamingJsonBuilder(Writer writer, JsonGenerator generator)

public StreamingJsonBuilder(Writer writer, Object content)

public StreamingJsonBuilder(Writer writer, Object content, JsonGenerator generator)

Method Detail

public Object call(Map m)

public void call(String name)

public Object call(List l)

public Object call(Object args)

public Object call(Iterable coll, @DelegatesTo(value = StreamingJsonDelegate.class, strategy = Closure.DELEGATE_FIRST) Closure c)

public Object call(Collection coll, @DelegatesTo(value = StreamingJsonDelegate.class, strategy = Closure.DELEGATE_FIRST) Closure c)

public Object call(@DelegatesTo(value = StreamingJsonDelegate.class, strategy = Closure.DELEGATE_FIRST) Closure c)

public void call(String name, @DelegatesTo(value = StreamingJsonDelegate.class, strategy = Closure.DELEGATE_FIRST) Closure c)

public void call(String name, Iterable coll, @DelegatesTo(value = StreamingJsonDelegate.class, strategy = Closure.DELEGATE_FIRST) Closure c)

public void call(String name, Collection coll, @DelegatesTo(value = StreamingJsonDelegate.class, strategy = Closure.DELEGATE_FIRST) Closure c)

public void call(String name, Map map, @DelegatesTo(value = StreamingJsonDelegate.class, strategy = Closure.DELEGATE_FIRST) Closure callable)

@Override public Object invokeMethod(String name, Object args)