SchemaBuilder (Apache Avro Java 1.11.1 API)

java.lang.Object
- org.apache.avro.SchemaBuilder

```
public class SchemaBuilder
extends Object
```
A fluent interface for building Schema instances. The flow of the API is designed to mimic the Avro Schema Specification
For example, the below JSON schema and the fluent builder code to create it are very similar:
```
 {
   "type": "record",
   "name": "HandshakeRequest", "namespace":"org.apache.avro.ipc",
   "fields": [
     {"name": "clientHash",
      "type": {"type": "fixed", "name": "MD5", "size": 16}},
     {"name": "clientProtocol", "type": ["null", "string"]},
     {"name": "serverHash", "type": "MD5"},
     {"name": "meta", "type": ["null", {"type": "map", "values": "bytes"}]}
   ]
 }
 
```
```
 Schema schema = SchemaBuilder.record("HandshakeRequest").namespace("org.apache.avro.ipc").fields().name("clientHash")
     .type().fixed("MD5").size(16).noDefault().name("clientProtocol").type().nullable().stringType().noDefault()
     .name("serverHash").type("MD5").noDefault().name("meta").type().nullable().map().values().bytesType().noDefault()
     .endRecord();
 
```
Usage Guide
SchemaBuilder chains together many smaller builders and maintains nested context in order to mimic the Avro Schema specification. Every Avro type in JSON has required and optional JSON properties, as well as user-defined properties.

Selecting and Building an Avro Type
The API analogy for the right hand side of the Avro Schema JSON
```
 "type":
 
```
is a SchemaBuilder.TypeBuilder, SchemaBuilder.FieldTypeBuilder, or SchemaBuilder.UnionFieldTypeBuilder, depending on the context. These types all share a similar API for selecting and building types.

Primitive Types
All Avro primitive types are trivial to configure. A primitive type in Avro JSON can be declared two ways, one that supports custom properties and one that does not:
```
 {"type":"int"}
 {"type":{"name":"int"}}
 {"type":{"name":"int", "customProp":"val"}}
 
```
The analogous code form for the above three JSON lines are the below three lines:
```
  .intType()
  .intBuilder().endInt()
  .intBuilder().prop("customProp", "val").endInt()
 
```
Every primitive type has a shortcut to create the trivial type, and a builder when custom properties are required. The first line above is a shortcut for the second, analogous to the JSON case.
Named Types
Avro named types have names, namespace, aliases, and doc. In this API these share a common parent, SchemaBuilder.NamespacedBuilder. The builders for named types require a name to be constructed, and optional configuration via:
SchemaBuilder.NamedBuilder.doc()
SchemaBuilder.NamespacedBuilder.namespace(String)
SchemaBuilder.NamedBuilder.aliases(String...)
SchemaBuilder.PropBuilder.prop(String, String)

Each named type completes configuration of the optional properties with its own method:

SchemaBuilder.FixedBuilder.size(int)
SchemaBuilder.EnumBuilder.symbols(String...)
SchemaBuilder.RecordBuilder.fields()

 .enumeration("Suit").namespace("org.apache.test")
   .aliases("org.apache.test.OldSuit")
   .doc("CardSuits")
   .prop("customProp", "val")
   .symbols("SPADES", "HEARTS", "DIAMONDS", "CLUBS")

 { "type":"enum",
   "name":"Suit", "namespace":"org.apache.test",
   "aliases":["org.apache.test.OldSuit"],
   "doc":"Card Suits",
   "customProp":"val",
   "symbols":["SPADES", "HEARTS", "DIAMONDS", "CLUBS"]
 }

Nested Types

SchemaBuilder.ArrayBuilder.items()

SchemaBuilder.MapBuilder.values()

Fields

SchemaBuilder.RecordBuilder.fields()

SchemaBuilder.FieldAssembler

SchemaBuilder.FieldAssembler.name(String)

SchemaBuilder.FieldBuilder

SchemaBuilder.FieldBuilder.type()

Fields have default values that must be specified to complete the field. SchemaBuilder.FieldDefault.noDefault() is available for all field types, and a specific method is available for each type to use a default, for example SchemaBuilder.IntDefault.intDefault(int)

There are field shortcut methods on SchemaBuilder.FieldAssembler for primitive types. These shortcuts create required, optional, and nullable fields, but do not support field aliases, doc, or custom properties.

Unions

SchemaBuilder.TypeBuilder.unionOf()

SchemaBuilder.FieldTypeBuilder.unionOf()

 .unionOf()
   .fixed("IPv4").size(4).and()
   .fixed("IPv6").size(16).and()
   .nullType().endUnion()

 [
   {"type":"fixed", "name":"IPv4", "size":4},
   {"type":"fixed", "name":"IPv6", "size":16},
   "null"
 ]

   .unionOf().intType().and().nullType().endUnion()
   .nullable().intType()

   .name("f").type().unionOf().nullType().and().longType().endUnion().nullDefault()
   .name("f").type().optional().longType()

Explicit Types and Types by Name

   .type(Schema.create(Schema.Type.INT)) // explicitly specified
   .type("MD5")                       // reference by full name or short name
   .type("MD5", "org.apache.avro.test")  // reference by name and namespace

builder(String) returns a type builder with a default namespace. builder() returns a type builder with no default namespace.

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`SchemaBuilder.ArrayBuilder<R>` Builds an Avro Array type with optional properties.
`static class`	`SchemaBuilder.ArrayDefault<R>` Choose whether to use a default value for the field or not.
`static class`	`SchemaBuilder.BaseFieldTypeBuilder<R>` A special Builder for Record fields.
`static class`	`SchemaBuilder.BaseTypeBuilder<R>` A common API for building types within a context.
`static class`	`SchemaBuilder.BooleanBuilder<R>` Builds an Avro boolean type with optional properties.
`static class`	`SchemaBuilder.BooleanDefault<R>` Choose whether to use a default value for the field or not.
`static class`	`SchemaBuilder.BytesBuilder<R>` Builds an Avro bytes type with optional properties.
`static class`	`SchemaBuilder.BytesDefault<R>` Choose whether to use a default value for the field or not.
`static class`	`SchemaBuilder.DoubleBuilder<R>` Builds an Avro double type with optional properties.
`static class`	`SchemaBuilder.DoubleDefault<R>` Choose whether to use a default value for the field or not.
`static class`	`SchemaBuilder.EnumBuilder<R>` Builds an Avro Enum type with optional properties, namespace, doc, and aliases.
`static class`	`SchemaBuilder.EnumDefault<R>` Choose whether to use a default value for the field or not.
`static class`	`SchemaBuilder.FieldAssembler<R>`
`static class`	`SchemaBuilder.FieldBuilder<R>` Builds a Field in the context of a `SchemaBuilder.FieldAssembler`.
`static class`	`SchemaBuilder.FieldDefault<R,S extends SchemaBuilder.FieldDefault<R,S>>` Abstract base class for field defaults.
`static class`	`SchemaBuilder.FieldTypeBuilder<R>` FieldTypeBuilder adds `SchemaBuilder.FieldTypeBuilder.unionOf()`, `SchemaBuilder.FieldTypeBuilder.nullable()`, and `SchemaBuilder.FieldTypeBuilder.optional()` to BaseFieldTypeBuilder.
`static class`	`SchemaBuilder.FixedBuilder<R>` Builds an Avro Fixed type with optional properties, namespace, doc, and aliases.
`static class`	`SchemaBuilder.FixedDefault<R>` Choose whether to use a default value for the field or not.
`static class`	`SchemaBuilder.FloatBuilder<R>` Builds an Avro float type with optional properties.
`static class`	`SchemaBuilder.FloatDefault<R>` Choose whether to use a default value for the field or not.
`static class`	`SchemaBuilder.GenericDefault<R>`
`static class`	`SchemaBuilder.IntBuilder<R>` Builds an Avro int type with optional properties.
`static class`	`SchemaBuilder.IntDefault<R>` Choose whether to use a default value for the field or not.
`static class`	`SchemaBuilder.LongBuilder<R>` Builds an Avro long type with optional properties.
`static class`	`SchemaBuilder.LongDefault<R>` Choose whether to use a default value for the field or not.
`static class`	`SchemaBuilder.MapBuilder<R>` Builds an Avro Map type with optional properties.
`static class`	`SchemaBuilder.MapDefault<R>` Choose whether to use a default value for the field or not.
`static class`	`SchemaBuilder.NamedBuilder<S extends SchemaBuilder.NamedBuilder<S>>` An abstract type that provides builder methods for configuring the name, doc, and aliases of all Avro types that have names (fields, Fixed, Record, and Enum).
`static class`	`SchemaBuilder.NamespacedBuilder<R,S extends SchemaBuilder.NamespacedBuilder<R,S>>` An abstract type that provides builder methods for configuring the namespace for all Avro types that have namespaces (Fixed, Record, and Enum).
`static class`	`SchemaBuilder.NullBuilder<R>` Builds an Avro null type with optional properties.
`static class`	`SchemaBuilder.NullDefault<R>` Choose whether to use a default value for the field or not.
`static class`	`SchemaBuilder.PropBuilder<S extends SchemaBuilder.PropBuilder<S>>` An abstract builder for all Avro types.
`static class`	`SchemaBuilder.RecordBuilder<R>`
`static class`	`SchemaBuilder.RecordDefault<R>` Choose whether to use a default value for the field or not.
`static class`	`SchemaBuilder.StringBldr<R>` Builds an Avro string type with optional properties.
`static class`	`SchemaBuilder.StringDefault<R>` Choose whether to use a default value for the field or not.
`static class`	`SchemaBuilder.TypeBuilder<R>` A Builder for creating any Avro schema type.
`static class`	`SchemaBuilder.UnionAccumulator<R>` Accumulates all of the types in a union.
`static class`	`SchemaBuilder.UnionFieldTypeBuilder<R>` Builder for a union field.

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static SchemaBuilder.ArrayBuilder<Schema>`	`array()` Create a builder for an Avro array This is equivalent to:
`static SchemaBuilder.TypeBuilder<Schema>`	`builder()` Create a builder for Avro schemas.
`static SchemaBuilder.TypeBuilder<Schema>`	`builder(String namespace)` Create a builder for Avro schemas with a default namespace.
`static SchemaBuilder.EnumBuilder<Schema>`	`enumeration(String name)` Create a builder for an Avro enum with the specified name and symbols (values).
`static SchemaBuilder.FixedBuilder<Schema>`	`fixed(String name)` Create a builder for an Avro fixed type with the specified name and size.
`static SchemaBuilder.MapBuilder<Schema>`	`map()` Create a builder for an Avro map This is equivalent to:
`static SchemaBuilder.BaseTypeBuilder<Schema>`	`nullable()` Create a builder for a union of a type and null.
`static SchemaBuilder.RecordBuilder<Schema>`	`record(String name)` Create a builder for an Avro record with the specified name.
`static SchemaBuilder.BaseTypeBuilder<SchemaBuilder.UnionAccumulator<Schema>>`	`unionOf()` Create a builder for an Avro union This is equivalent to:

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

builder

public static SchemaBuilder.TypeBuilder<Schema> builder()

Create a builder for Avro schemas.

builder
```
public static SchemaBuilder.TypeBuilder<Schema> builder(String namespace)
```
Create a builder for Avro schemas with a default namespace. Types created without namespaces will inherit the namespace provided.

record
```
public static SchemaBuilder.RecordBuilder<Schema> record(String name)
```
Create a builder for an Avro record with the specified name. This is equivalent to:
```
 builder().record(name);
 
```
Parameters:

name - the record name

enumeration
```
public static SchemaBuilder.EnumBuilder<Schema> enumeration(String name)
```
Create a builder for an Avro enum with the specified name and symbols (values). This is equivalent to:
```
 builder().enumeration(name);
 
```
Parameters:

name - the enum name

fixed
```
public static SchemaBuilder.FixedBuilder<Schema> fixed(String name)
```
Create a builder for an Avro fixed type with the specified name and size. This is equivalent to:
```
 builder().fixed(name);
 
```
Parameters:

name - the fixed name

array

public static SchemaBuilder.ArrayBuilder<Schema> array()

Create a builder for an Avro array This is equivalent to:

 builder().array();

map

public static SchemaBuilder.MapBuilder<Schema> map()

Create a builder for an Avro map This is equivalent to:

 builder().map();

unionOf

public static SchemaBuilder.BaseTypeBuilder<SchemaBuilder.UnionAccumulator<Schema>> unionOf()

Create a builder for an Avro union This is equivalent to:

 builder().unionOf();

nullable

public static SchemaBuilder.BaseTypeBuilder<Schema> nullable()

Create a builder for a union of a type and null. This is a shortcut for:

 builder().nullable();

and the following two lines are equivalent:

 nullable().intType();

 unionOf().intType().and().nullType().endUnion();

Class SchemaBuilder

Usage Guide

Selecting and Building an Avro Type

Primitive Types

Named Types

Nested Types

Fields

Unions

Explicit Types and Types by Name

Nested Class Summary

Method Summary

Methods inherited from class java.lang.Object

Method Detail

builder

builder

record

enumeration

fixed

array

map

unionOf

nullable