Parsers provide fine-grained configuration for inbound data. You configure parsers with stages, much like index pipelines and query pipelines. Parsers can include conditional parsing and nested parsing. You can configure them through the Managed Fusion UI or the Parsers API. Connectors receive the inbound data, convert it into a byte stream, and send the byte stream to a parser’s configured parsing stages. The parser selects a parsing stage to handle the stream, which parses the data and produces documents that are sent to the index pipeline. Each parsing stage evaluates whether the inbound stream matches the stage’s default media types or filename extensions. The first stage that finds a match processes the data and can output one or both of the following:
  • Zero or more pipeline documents for consumption by the index pipeline
  • Zero or more new input streams for re-parsing
    This recursive approach is useful for containers (for example, zip and tar files). The output of the container parsing can be another container or a stream of uncompressed content that requires its own parsing.
Stages that might match the stream beyond the first match will not be used. A few static fields impact the overall parser configuration. They are accessible when you select the parser in the Index Workbench:
FieldDescription
Document ID Source FieldField in the source file that contains the document ID
Maximum Parser Recursion DepthMaximum number of times the parser may recurse over the file, before proceeding to the next parser. This is useful for files with hierarchical structures (for example, zip and tar files).
Enable automatic media type detectionWhether to automatically detect the media type of the source files. If disabled, the parser uses the media type application/octet-stream.

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Built-in parser stages

The parser stages found in the sidenav are available for configuration. Datasources that use connectors that retrieve fixed-structure content, such as those for Twitter and Jira, have hard-coded parsers and do not expose any configurable parser options.

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Configure parsers

When you configure a datasource, you can use the Index Workbench or the Parsers API to create a parser. A parser consists of an ordered list of parser stages, some global parser parameters, and the stage-specific parameters. You can re-order the stages list by dragging them up or down in the Index Workbench. Any parser stage can be added to the same parser multiple times if different configuration options are needed for different stages. Datasources with fixed-structure data will also be parsed by Managed Fusion, but with default settings that do not need to be customized. There is no limit to the number of stages that can be included in a parser. The priority-order of the stages is completely flexible. In a default parser configuration, a fallback parser is provided at the end of the parsing stage list to handle streams no other stage matches. If present, this stage is selected and attempts to parse anything that has not yet been matched.
When entering configuration values in the UI, use unescaped characters, such as \t for the tab character. When entering configuration values in the API, use escaped characters, such as \\t for the tab character.

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Configure a parser in the Managed Fusion UI in Index Workbench

To configure parsers under Indexing > Index Workbench:
  1. In the Managed Fusion workspace, navigate to the Index Workbench.
  2. At the upper right of the Index Workbench panel, click Load.
  3. Under Load, click the name of the index pipeline.
  4. Click the parser to open its configuration: Parser
  5. Click a specific stage to open its configuration panel: Parser stage configuration

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Configure a parser in the Managed Fusion UI in Parsers

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Requirements

To configure each part of the indexing process separately instead of using the Index Workbench, you must complete the following:
  • Configure datasources in Indexing > Datasources. For more information, see Configure a new datasource.
  • Configure parsers in Indexing > Parsers using the steps in this section.
  • Configure index pipelines in Indexing > Index Pipelines. For more information, see Index Pipeline Stages.

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Configure a parser in Index > Parsers

  1. In the Managed Fusion workspace, navigate to Indexing > Parsers.
  2. Click Add.
Parser configuration screen
  1. In the Parser ID field, enter a unique identifier for the parser. For example, CSV_parser.
  2. In the Document ID Source Field, enter the dataset field to use as the document ID. For example, docID.
  3. In the Maximum Parser Recursion Depth field, enter the maximum of times this parser can recurse over any document before proceeding to the next parser. For example, 16.
  4. Select the Enable automatic media type detection checkbox to automatically detect the Content-Type of each document. If this is not selected, application/octet-stream is used.
  5. Select the Detect media type based on extension checkbox to use the file extension to detect the Content-Type of a document before attempting to detect type based on content.
  6. In the Maximum Document Field Length field, enter the maximum number of bytes allowed in the document. If a field exceeds this length, the field is truncated to this number.
  7. Click Add a parser stage and select the parser to open its configuration. For example, CSV. To review configuration information for each parser type, click that parser topic in the sidebar.
  8. Click Save.

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Configure a parser in the REST API

The Parsers API provides a programmatic interface for viewing, creating, and modifying parsers, as well as sending documents directly to a parser.
  • To get all currently-defined parsers: https://EXAMPLE_COMPANY.lucidworks.cloud/api/parsers/
  • To get the parser schema: https://EXAMPLE_COMPANY.lucidworks.cloud/api/parsers/_schema
Replace EXAMPLE_COMPANY with the name provided by your Lucidworks representative.
Here is a very simple parser example, for parsing JSON input: 
{ "id": "simple-json",
  "type": "json",
             arbitrary parser-specific options here.
        "prettify": false
}
The example below shows a parser that can parse JSON input, as well as JSON that is inside zip, tar, or gzip containers, or any combination (such as .tar.gz). The order of the stages begins with the outermost containers and ends with the innermost content. 
{ "id": "default-json",
  "type": "composite",
  "parsers": [
    { "id" : "zip-parser",
      "type" : "zip" },
    { "type" : "gz" },
    { "type" : "tar" },
    { "id": "json-parser",
      "type": "json",
      "prettify": false
    }]
}
ID is optional, just as in pipeline stages. Many parser stages require no configuration other than type.

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Field parser index pipeline stage

The parsers themselves only parse whole documents. Parsing of content embedded in fields is performed separately by the Field Parser index pipeline stage. This stage identifies the field that requires parsing and the parser to use.