JsonPathReader

Description:

Parses JSON records and evaluates user-defined JSON Path's against each JSON object. While the reader expects each record to be well-formed JSON, the content of a FlowFile may consist of many records, each as a well-formed JSON array or JSON object with optional whitespace between them, such as the common 'JSON-per-line' format. If an array is encountered, each element in that array will be treated as a separate record. User-defined properties define the fields that should be extracted from the JSON in order to form the fields of a Record. Any JSON field that is not extracted via a JSONPath will not be returned in the JSON Records.

Additional Details...

Tags:

json, jsonpath, record, reader, parser

Properties:

In the list below, the names of required properties appear in bold. Any other properties (not in bold) are considered optional. The table also indicates any default values, and whether a property supports the NiFi Expression Language.

NameDefault ValueAllowable ValuesDescription
Schema Access Strategyinfer-schema
  • Use 'Schema Name' Property The name of the Schema to use is specified by the 'Schema Name' Property. The value of this property is used to lookup the Schema in the configured Schema Registry service.
  • Use 'Schema Text' Property The text of the Schema itself is specified by the 'Schema Text' Property. The value of this property must be a valid Avro Schema. If Expression Language is used, the value of the 'Schema Text' property must be valid after substituting the expressions.
  • HWX Schema Reference Attributes The FlowFile contains 3 Attributes that will be used to lookup a Schema from the configured Schema Registry: 'schema.identifier', 'schema.version', and 'schema.protocol.version'
  • HWX Content-Encoded Schema Reference The content of the FlowFile contains a reference to a schema in the Schema Registry service. The reference is encoded as a single byte indicating the 'protocol version', followed by 8 bytes indicating the schema identifier, and finally 4 bytes indicating the schema version, as per the Hortonworks Schema Registry serializers and deserializers, found at https://github.com/hortonworks/registry
  • Confluent Content-Encoded Schema Reference The content of the FlowFile contains a reference to a schema in the Schema Registry service. The reference is encoded as a single 'Magic Byte' followed by 4 bytes representing the identifier of the schema, as outlined at http://docs.confluent.io/current/schema-registry/docs/serializer-formatter.html. This is based on version 3.2.x of the Confluent Schema Registry.
  • Infer Schema The Schema of the data will be inferred automatically when the data is read. See component Usage and Additional Details for information about how the schema is inferred.
Specifies how to obtain the schema that is to be used for interpreting the data.
Schema RegistryController Service API:
SchemaRegistry
Implementations: HortonworksSchemaRegistry
ConfluentSchemaRegistry
AvroSchemaRegistry
Specifies the Controller Service to use for the Schema Registry

This Property is only considered if the <Schema Access Strategy> Property is set to one of the following values: "confluent-encoded", "schema-name", "hwx-schema-ref-attributes", "hwx-content-encoded-schema"
Schema Name${schema.name}Specifies the name of the schema to lookup in the Schema Registry property
Supports Expression Language: true (will be evaluated using flow file attributes and variable registry)

This Property is only considered if the <Schema Access Strategy> Property has a value of "schema-name".
Schema VersionSpecifies the version of the schema to lookup in the Schema Registry. If not specified then the latest version of the schema will be retrieved.
Supports Expression Language: true (will be evaluated using flow file attributes and variable registry)

This Property is only considered if the <Schema Access Strategy> Property has a value of "schema-name".
Schema BranchSpecifies the name of the branch to use when looking up the schema in the Schema Registry property. If the chosen Schema Registry does not support branching, this value will be ignored.
Supports Expression Language: true (will be evaluated using flow file attributes and variable registry)

This Property is only considered if the <Schema Access Strategy> Property has a value of "schema-name".
Schema Text${avro.schema}The text of an Avro-formatted Schema
Supports Expression Language: true (will be evaluated using flow file attributes and variable registry)

This Property is only considered if the <Schema Access Strategy> Property has a value of "schema-text-property".
Date FormatSpecifies the format to use when reading/writing Date fields. If not specified, Date fields will be assumed to be number of milliseconds since epoch (Midnight, Jan 1, 1970 GMT). If specified, the value must match the Java Simple Date Format (for example, MM/dd/yyyy for a two-digit month, followed by a two-digit day, followed by a four-digit year, all separated by '/' characters, as in 01/01/2017).
Time FormatSpecifies the format to use when reading/writing Time fields. If not specified, Time fields will be assumed to be number of milliseconds since epoch (Midnight, Jan 1, 1970 GMT). If specified, the value must match the Java Simple Date Format (for example, HH:mm:ss for a two-digit hour in 24-hour format, followed by a two-digit minute, followed by a two-digit second, all separated by ':' characters, as in 18:04:15).
Timestamp FormatSpecifies the format to use when reading/writing Timestamp fields. If not specified, Timestamp fields will be assumed to be number of milliseconds since epoch (Midnight, Jan 1, 1970 GMT). If specified, the value must match the Java Simple Date Format (for example, MM/dd/yyyy HH:mm:ss for a two-digit month, followed by a two-digit day, followed by a four-digit year, all separated by '/' characters; and then followed by a two-digit hour in 24-hour format, followed by a two-digit minute, followed by a two-digit second, all separated by ':' characters, as in 01/01/2017 18:04:15).

Dynamic Properties:

Dynamic Properties allow the user to specify both the name and value of a property.

NameValueDescription
The field name for the record.A JSONPath Expression that will be evaluated against each JSON record. The result of the JSONPath will be the value of the field whose name is the same as the property name.User-defined properties identify how to extract specific fields from a JSON object in order to create a Record
Supports Expression Language: false

State management:

This component does not store state.

Restricted:

This component is not restricted.

System Resource Considerations:

None specified.

See Also:

JsonTreeReader