Schema (CDAP API Common 3.3.7 API)

java.lang.Object
- co.cask.cdap.api.data.schema.Schema

@Beta
public final class Schema
extends Object

This class represents schema of data types.

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class Schema.Field
Represents a field inside a Schema.Type.RECORD schema.

static class Schema.Type
Types known to Schema.

Nested Classes
Modifier and Type	Class and Description
`static class`	`Schema.Field` Represents a field inside a `Schema.Type.RECORD` schema.
`static class`	`Schema.Type` Types known to Schema.

Method Summary

Methods
Modifier and Type	Method and Description
`static Schema`	`arrayOf(Schema componentSchema)` Creates an `ARRAY` `Schema` of the given component type.
`static Schema`	`enumWith(Class<Enum<?>> enumClass)` Creates a `Schema` of `ENUM` type, with values extracted from the given `Enum` class.
`static Schema`	`enumWith(Iterable<String> values)` Creates a `Schema` of `ENUM` type, with the given enum values.
`static Schema`	`enumWith(String... values)` Creates a `Schema` of `ENUM` type, with the given enum values.
`boolean`	`equals(Object other)`
`Schema`	`getComponentSchema()`
`int`	`getEnumIndex(String value)`
`String`	`getEnumValue(int idx)`
`Set<String>`	`getEnumValues()`
`Schema.Field`	`getField(String name)` Returns the record `Schema.Field` of the given name.
`List<Schema.Field>`	`getFields()`
`Map.Entry<Schema,Schema>`	`getMapSchema()`
`Schema`	`getNonNullable()` Assuming this is a union of a null and one non-null type, return the non-null schema.
`String`	`getRecordName()`
`SchemaHash`	`getSchemaHash()`
`Schema.Type`	`getType()`
`Schema`	`getUnionSchema(int idx)`
`List<Schema>`	`getUnionSchemas()`
`int`	`hashCode()`
`boolean`	`isCompatible(Schema target)` Checks if the given target schema is compatible with this schema, meaning datum being written with this schema could be projected correctly into the given target schema.
`boolean`	`isNullable()` Check if this is a nullable type, which is a union of a null and one other non-null type.
`boolean`	`isNullableSimple()` Check if this is a nullable simple type, which is a union of a null and one other non-null simple type, where a simple type is a boolean, int, long, float, double, bytes, or string type.
`boolean`	`isSimpleOrNullableSimple()` Check if this is a simple type or a nullable simple type, which is a union of a null and one other non-null simple type, where a simple type is a boolean, int, long, float, double, bytes, or string type.
`static Schema`	`mapOf(Schema keySchema, Schema valueSchema)` Creates a `MAP` `Schema` of the given key and value types.
`static Schema`	`nullableOf(Schema schema)` Creates a nullable `Schema` for the given schema, which is a union of the given schema with the null type.
`static Schema`	`of(Schema.Type type)` Creates a `Schema` for the given type.
`static Schema`	`parseJson(Reader reader)` Parse the given json representation of a schema object contained in a reader into a schema object.
`static Schema`	`parseJson(String schemaJson)` Parse the given JSON representation, as returned by `toString()` into a Schema object.
`static Schema`	`parseSQL(String schemaString)` Parse the given sql-like schema representation into a schema object.
`static Schema`	`recordOf(String name)` Creates a `RECORD` `Schema` of the given name.
`static Schema`	`recordOf(String name, Iterable<Schema.Field> fields)` Creates a `RECORD` `Schema` with the given name and `Fields`.
`static Schema`	`recordOf(String name, Schema.Field... fields)` Creates a `RECORD` `Schema` with the given name and `Fields`.
`String`	`toString()`
`static Schema`	`unionOf(Iterable<Schema> schemas)` Creates a `UNION` `Schema` which represents a union of all the given schemas.
`static Schema`	`unionOf(Schema... schemas)` Creates a `UNION` `Schema` which represents a union of all the given schemas.

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

- Method Detail
  - parseJson
```
public static Schema parseJson(String schemaJson)
                        throws IOException
```
    Parse the given JSON representation, as returned by toString() into a Schema object.
    
    Parameters:
    schemaJson - the json representation of the schema
    
    Returns:
    the json representation parsed into a schema object
    
    Throws:
    
    IOException - if there was an exception parsing the schema
  - parseJson
```
public static Schema parseJson(Reader reader)
                        throws IOException
```
    Parse the given json representation of a schema object contained in a reader into a schema object.
    
    Parameters:
    reader - the reader for reading the json representation of a schema
    
    Returns:
    the parsed schema object
    
    Throws:
    
    IOException - if there was an exception parsing the schema
  - parseSQL
```
public static Schema parseSQL(String schemaString)
                       throws IOException
```
    Parse the given sql-like schema representation into a schema object. Input is expected to be a comma separated list of names and types, where the type is a primitive type, array, map, record, or union. The input will be parsed in a case insensitive manner.
```
 column_name data_type, ...

 data_type : primitive_type
 | array_type
 | map_type
 | record_type
 | union_type
 [ not null ]

 primitive_type: boolean
 | int
 | long
 | float
 | double
 | bytes
 | string

 array_type: array<data_type>

 map_type: map<data_type, data_type>

 record_type: record<field_name:data_type, ...>

 union_type: union<data_type, data_type, ...>
 
 
```
    Parameters:
    schemaString - the schema to parse
    
    Returns:
    the parsed schema object
    
    Throws:
    
    IOException - if there was an exception parsing the schema
  - of
```
public static Schema of(Schema.Type type)
```
    Creates a Schema for the given type. The type given must be a Simple Type.
    
    Parameters:
    type - Type of the schema to create.
    
    Returns:
    A Schema with the given type.
  - nullableOf
```
public static Schema nullableOf(Schema schema)
```
    Creates a nullable Schema for the given schema, which is a union of the given schema with the null type. The type given must not be the null type.
    
    Parameters:
    schema - Schema to union with the null type.
    
    Returns:
    A nullable version of the given Schema.
  - enumWith
```
public static Schema enumWith(String... values)
```
    Creates a Schema of ENUM type, with the given enum values. The set of values given should be unique and must contains at least one value. The ordering of values in the enum type schema would be the same as the order being passed in.
    
    Parameters:
    values - Enum values.
    
    Returns:
    A Schema of ENUM type.
  - enumWith
```
public static Schema enumWith(Iterable<String> values)
```
    Creates a Schema of ENUM type, with the given enum values. The set of values given should be unique and must contains at least one value. The ordering of values in the enum type schema would be the same as the Iterable.iterator() order.
    
    Parameters:
    values - Enum values.
    
    Returns:
    A Schema of ENUM type.
  - enumWith
```
public static Schema enumWith(Class<Enum<?>> enumClass)
```
    Creates a Schema of ENUM type, with values extracted from the given Enum class. The ordering of values in the enum type schema would be the same as the Enum.ordinal() order.
    
    Parameters:
    enumClass - Enum values.
    
    Returns:
    A Schema of ENUM type.
  - arrayOf
```
public static Schema arrayOf(Schema componentSchema)
```
    Creates an ARRAY Schema of the given component type.
    
    Parameters:
    componentSchema - Schema of the array component.
    
    Returns:
    A Schema of ARRAY type.
  - mapOf
```
public static Schema mapOf(Schema keySchema,
           Schema valueSchema)
```
    Creates a MAP Schema of the given key and value types.
    
    Parameters:
    keySchema - Schema of the map key.
    valueSchema - Schema of the map value
    
    Returns:
    A Schema of MAP type.
  - recordOf
```
public static Schema recordOf(String name)
```
    Creates a RECORD Schema of the given name. The schema created doesn't carry any record fields, which makes it only useful to be used as a component schema for other schema type, where the actual schema is resolved from the top level container schema.
    
    Parameters:
    name - Name of the record.
    
    Returns:
    A Schema of RECORD type.
  - recordOf
```
public static Schema recordOf(String name,
              Schema.Field... fields)
```
    Creates a RECORD Schema with the given name and Fields. The ordering of the fields inside the record would be the same as the one being passed in.
    
    Parameters:
    name - Name of the record
    fields - All the fields that the record contains.
    
    Returns:
    A Schema of RECORD type.
  - recordOf
```
public static Schema recordOf(String name,
              Iterable<Schema.Field> fields)
```
    Creates a RECORD Schema with the given name and Fields. The ordering of the fields inside the record would be the same as the Iterable.iterator() order.
    
    Parameters:
    name - Name of the record
    fields - All the fields that the record contains.
    
    Returns:
    A Schema of RECORD type.
  - unionOf
```
public static Schema unionOf(Schema... schemas)
```
    Creates a UNION Schema which represents a union of all the given schemas. The ordering of the schemas inside the union would be the same as the one being passed in.
    
    Parameters:
    schemas - All the Schemas constitutes the union.
    
    Returns:
    A Schema of UNION type.
  - unionOf
```
public static Schema unionOf(Iterable<Schema> schemas)
```
    Creates a UNION Schema which represents a union of all the given schemas. The ordering of the schemas inside the union would be the same as the Iterable.iterator() order.
    
    Parameters:
    schemas - All the Schemas constitutes the union.
    
    Returns:
    A Schema of UNION type.
  - getType
```
public Schema.Type getType()
```
    Returns:
    The Schema.Type that this schema represents.
  - getEnumValues
```
public Set<String> getEnumValues()
```
    Returns:
    An immutable Set of enum values or null if this is not a ENUM schema. The Set.iterator() order would be the enum values orders.
  - getEnumIndex
```
public int getEnumIndex(String value)
```
    Parameters:
    value - The enum value
    
    Returns:
    The 0-base index of the given value in the enum values or -1 if this is not a ENUM schema.
  - getEnumValue
```
public String getEnumValue(int idx)
```
    Parameters:
    idx - The index in the enum values
    
    Returns:
    The string represents the enum value, or null if this is not a ENUM schema or the given index is invalid.
  - getComponentSchema
```
public Schema getComponentSchema()
```
    Returns:
    The schema of the array component or null if this is not a ARRAY schema.
  - getMapSchema
```
public Map.Entry<Schema,Schema> getMapSchema()
```
    Returns:
    An immutable Map.Entry if this is a Type#MAP MAP schema or null otherwise. The Map.Entry#getKey() would returns the key schema, while Map.Entry#getValue() would returns the value schema.
  - getRecordName
```
public String getRecordName()
```
    Returns:
    Name of the record if this is a RECORD schema or null otherwise.
  - getFields
```
public List<Schema.Field> getFields()
```
    Returns:
    An immutable List of record Fields if this is a RECORD schema or null otherwise.
  - getField
```
public Schema.Field getField(String name)
```
    Returns the record Schema.Field of the given name.
    
    Parameters:
    name - Name of the field
    
    Returns:
    A Schema.Field or null if there is no such field in this record or this is not a RECORD schema.
  - getUnionSchemas
```
public List<Schema> getUnionSchemas()
```
    Returns:
    An immutable List of schemas inside this union or null if this is not a UNION schema.
  - getUnionSchema
```
public Schema getUnionSchema(int idx)
```
    Parameters:
    idx - Index to the union schemas
    
    Returns:
    A Schema of the given union index or null if this is not a UNION schema or the given index is invalid.
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
    
    Returns:
    a JSON representation of this schema, which can be parsed with parseJson(java.lang.String)
  - equals
```
public boolean equals(Object other)
```
    Overrides:
    
    equals in class Object
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object
  - getSchemaHash
```
public SchemaHash getSchemaHash()
```
    Returns:
    A MD5 hash of this schema.
  - isCompatible
```
public boolean isCompatible(Schema target)
```
    Checks if the given target schema is compatible with this schema, meaning datum being written with this schema could be projected correctly into the given target schema. TODO: Add link to document of the target type projection.
    
    Parameters:
    target - Schema to check for compatibility to this target
    
    Returns:
    true if the schemas are compatible, false otherwise.
  - isNullable
```
public boolean isNullable()
```
    Check if this is a nullable type, which is a union of a null and one other non-null type.
    
    Returns:
    true if it is a nullable type, false if not.
  - isNullableSimple
```
public boolean isNullableSimple()
```
    Check if this is a nullable simple type, which is a union of a null and one other non-null simple type, where a simple type is a boolean, int, long, float, double, bytes, or string type.
    
    Returns:
    whether or not this is a nullable simple type.
  - isSimpleOrNullableSimple
```
public boolean isSimpleOrNullableSimple()
```
    Check if this is a simple type or a nullable simple type, which is a union of a null and one other non-null simple type, where a simple type is a boolean, int, long, float, double, bytes, or string type.
    
    Returns:
    whether or not this is a nullable simple type.
  - getNonNullable
```
public Schema getNonNullable()
```
    Assuming this is a union of a null and one non-null type, return the non-null schema.
    
    Returns:
    non-null schema from a union of a null and non-null schema.

Class Schema

Nested Class Summary

Method Summary

Methods inherited from class java.lang.Object

Method Detail

parseJson

parseJson

parseSQL

of

nullableOf

enumWith

enumWith

enumWith

arrayOf

mapOf

recordOf

recordOf

recordOf

unionOf

unionOf

getType

getEnumValues

getEnumIndex

getEnumValue

getComponentSchema

getMapSchema

getRecordName

getFields

getField

getUnionSchemas

getUnionSchema

toString

equals

hashCode

getSchemaHash

isCompatible

isNullable

isNullableSimple

isSimpleOrNullableSimple

getNonNullable