The JSON to Tuple Java operator converts JSON strings to StreamBase tuples. The operator's input port schema must contain a user defined string field that passes an JSON-encoded string to the operator. The operator parses the JSON string and populates tuple fields corresponding to the data found in the string. Each JSON string enqueued to the operator results in a single tuple emitted on its output port.
The operator's output schema determines the set of fields retrieved from the JSON string. The hierarchy of the fields in the schema must match that of the elements in the JSON string. Fields not present in the JSON string are set to null in the emitted tuple.
This section describes the properties you can set for a JSON to Tuple operator, using the various tabs of the Properties view in StreamBase Studio.
Name: Use this required field to specify or change the name of this instance of this component. The name must be unique within the current EventFlow module. The name can contain alphanumeric characters, underscores, and escaped special characters. Special characters can be escaped as described in Identifier Naming Rules. The first character must be alphabetic or an underscore.
Operator: A read-only field that shows the formal name of the operator.
Class name: Shows the fully qualified class name that implements the functionality of this operator. If you need to reference this class name elsewhere in your application, you can right-click this field and select Copy from the context menu to place the full class name in the system clipboard.
Start options: This field provides a link to the Cluster Aware tab, where you configure the conditions under which this operator starts.
Enable Error Output Port: Select this checkbox to add an Error Port to this component. In the EventFlow canvas, the Error Port shows as a red output port, always the last port for the component. See Using Error Ports to learn about Error Ports.
Description: Optionally, enter text to briefly describe the purpose and function of the component. In the EventFlow Editor canvas, you can see the description by pressing Ctrl while the component's tooltip is displayed.
| Property | Description |
|---|---|
| JSON Field Name | The name of the field in the inbound tuple that contains the JSON string to convert to a tuple. |
| Enable Status Port | If enabled (the default), status tuples are sent to port 2. If disabled, No status is reported. If disabled after previously being enabled, the arc connected to port 2 is deleted. |
| Enable Pass Through Fields | If enabled, inbound tuples are copied to the outbound tuple. |
| Pass Through Fields Field Name | The name of the field in the output tuple that is to contain a tuple of all the inbound data. |
| Log Level | Controls the level of verbosity the adapter uses to send notifications to the console. This setting can be higher than the containing application's log level. If set lower, the system log level is used. Available values, in increasing order of verbosity, are: OFF, ERROR, WARN, INFO, DEBUG, TRACE. |
| Property | Description |
|---|---|
| Timestamp Format | The format to use when converting time string values to timestamps. |
| Enable Loose Parsing | If enabled, the parsing of the JSON string ignores fields that do not match the schema. |
Use the Edit Schema tab to specify the schema of the output tuple for this adapter. For general instructions on using the Edit Schema tab, see the Properties: Edit Schema Tab section of the Defining Input Streams page.
Use the settings in this tab to enable this operator or adapter for runtime start and stop conditions in a multi-node cluster. During initial development of the fragment that contains this operator or adapter, and for maximum compatibility with releases before 10.5.0, leave the Cluster start policy control in its default setting, Start with module.
Cluster awareness is an advanced topic that requires an understanding of StreamBase Runtime architecture features, including clusters, quorums, availability zones, and partitions. See Cluster Awareness Tab Settings on the Using Cluster Awareness page for instructions on configuring this tab.
Use the Concurrency tab to specify parallel regions for this instance of this component, or multiplicity options, or both. The Concurrency tab settings are described in Concurrency Options, and dispatch styles are described in Dispatch Styles.
Caution
Concurrency settings are not suitable for every application, and using these settings requires a thorough analysis of your application. For details, see Execution Order and Concurrency, which includes important guidelines for using the concurrency options.
The operator has one input port and two output ports to communicate with the surrounding application.
The JSON to Tuple operator's ports are used as follows:
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DataIn: The JSON message to be converted to a tuple. The DataIn port can have any schema but must contain at least the field specified by the
JSON Field Nameproperty -
TupleOut: This output port contains one or more top-level fields, each of which is used to receive the results of JSON string. If
Enable Pass Through Fieldsis checked this port will also contain all the fields from the input port using the specifiedPass Through Fields Field Nameproperty as the name -
Status: A tuple is emitted on this port when an attempt to convert an JSON string to a tuple fails. The Status port has the following schema:
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type, string: Contains the following value describing the type of event that occurred:
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Convert
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action, string: Contains the following value indicating the conversion failed:
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Failed
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object, string: Contains a string representation of the input tuple.
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message, string: Contains a human-readable description of the conversion failure.
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time, timestamp: Contains the time of the conversion failure.
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inputTuple, tuple: Contains a copy of the input tuple.
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