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  5. Flat File Format

Flat File Format

MIME type: application/flatfile

ID: flatfile

The Flat File format supports multiple types of fixed width records within a single message. The schema structure allows you to define how different record types are distinguished, and how the records are logically grouped.

Flat File in DataWeave supports files of up to 15 MB, and the memory requirement is roughly 40 to 1. For example, a 1-MB file requires up to 40 MB of memory to process, so it’s important to consider this memory requirement in conjunction with your TPS needs for large flat files. This is not an exact figure; the value might vary according to the complexity of the mapping instructions.

Example: Specify a Flat File Schema

This example shows a DataWeave script that outputs data in the Flat File format. Notice that it uses the schemaPath and structureIndent writer properties.

%dw 2.0
output application/flatfile schemaPath="src/main/resources/test-data/QBReqRsp.esl", structureIdent="QBResponse"
---
payload

Configuration Properties

DataWeave supports the following configuration properties for this format.

Reader Properties

This format accepts properties that provide instructions for reading input data.

Parameter Type Default Description

allowLenientWithBinaryNotEndElement

Boolean

false

When the schema contains elements of type Binary or Packed, the lenient option does not allow short records, regardless of the last element’s format type. When you set this property to true, the validation applies only to cases in which the record ends with type Binary or Packed.

Valid values are true or false.

enforceRequires

Boolean

false

Produces an error when set to true if a required value is missing.

Valid values are true or false.

missingValues

String

null

Fill character used to represent missing values. To activate a non-default setting, set the useMissCharAsDefaultForFill property to true, and use one of the following values to missingValues:

  • none (for the reader) or NONE (for the writer): Treats all data as values.

  • spaces (for the reader) or SPACES (for the writer): Interprets a field consisting of only spaces as a missing value. Default for flat file and fixed-width formats.

  • zeroes (for the reader) or ZEROES (for the writer): Interprets numeric fields consisting of only 0 characters and character fields consisting of only spaces as missing values.

  • nulls (for the reader) or NULLS (for the writer): Interprets a field consisting only of 0 bytes as a missing value. Default for COBOL copybook schema.

Valid values are none or spaces or zeroes or nulls.

notTruncateDependingOnSubjectNotPresent

Boolean

false

Fills the entire group when the DEPENDING ON subject is not present.

Valid values are true or false.

recordParsing

String

'strict'

Specifies the expected type of separation between lines or records:

  • strict: Line break is expected at exact end of each record. strict is the default.

  • lenient: Line break is used, but records can be shorter or longer than the schema specifies.

  • noTerminator: Records follow one another with no separation.

  • singleRecord: The entire input is a single record.

Note that schemas with type Binary or Packed don’t allow for line break detection, so setting recordParsing to lenient only allows long records to be handled, not short ones. These schemas also currently only work with certain single-byte character encodings (so not with UTF-8 or any multibyte format).

Valid values are strict or lenient or noTerminator or singleRecord.

retainEmptyStringFieldsOnParsing

Boolean

false

Allow parsing behavior to keep missing string value fields with a default value in the output map

Valid values are true or false.

schemaPath (Required)

String

null

Path to the schema definition. Specifies the location in your local disk of the schema file that parses your input.

segmentIdent

String

null

Segment identifier in the schema for fixed-width or COBOL copybook schemas. Required when parsing a single segment or record definition if the schema includes multiple segment definitions.

structureIdent

String

null

Structure identifier in the schema for flat file schemas. Required when parsing a structure definition if the schema includes multiple structure definitions.

truncateDependingOn

Boolean

false

For COBOL copybook, truncates DEPENDING ON values to the length used.

Valid values are true or false.

useMissCharAsDefaultForFill

Boolean

false

By default, the flat file reader and writer use spaces for missing characters and ignore the setting of the missingValues property. When you set this property to true, DataWeave honors the setting of the missingValues property. Introduced in DataWeave 2.3 (2.3.0-20210823) for the September 2021 release of Mule 4.3.0-20210823.

Valid values are true or false.

zonedDecimalStrict

Boolean

false

For COBOL copybook, uses the 'strict' ASCII form of sign encoding for zoned decimal values.

Valid values are true or false.

Writer Properties

This format accepts properties that provide instructions for writing output data.

Parameter Type Default Description

bufferSize

Number

8192

Size of the buffer writer, in bytes. The value must be greater than 8.

deferred

Boolean

false

Generates the output as a data stream when set to true, and defers the script’s execution until the generated content is consumed.

Valid values are true or false.

encoding

String

null

The encoding to use for the output, such as UTF-8.

enforceRequires

Boolean

false

Produces an error when set to true if a required value is missing.

Valid values are true or false.

missingValues

String

null

Fill character used to represent missing values. To activate a non-default setting, set the useMissCharAsDefaultForFill property to true, and use one of the following values to missingValues:

  • NONE: Write nothing for missing values.

  • spaces (for the reader) or SPACES (for the writer): Interprets a field consisting of only spaces as a missing value. Default for flat file and fixed-width formats.

  • zeroes (for the reader) or ZEROES (for the writer): Interprets numeric fields consisting of only 0 characters and character fields consisting of only spaces as missing values.

  • nulls (for the reader) or NULLS (for the writer): Interprets a field consisting only of 0 bytes as a missing value. Default for COBOL copybook schema.

Valid values are none or spaces or zeroes or nulls.

notTruncateDependingOnSubjectNotPresent

Boolean

false

Fills the entire group when the DEPENDING ON subject is not present.

Valid values are true or false.

recordTerminator

String

null

Line break for a record separator. Valid values: lf, cr, crlf, none. DataWeave uses this property as a separator only when there are multiple records. Values translate directly to character codes, and none leaves no termination on each record.

schemaPath (Required)

String

null

Path to the schema definition. Specifies the location in your local disk of the schema file that parses your input.

segmentIdent

String

null

Segment identifier in the schema for fixed-width or COBOL copybook schemas. Required when parsing a single segment or record definition if the schema includes multiple segment definitions.

structureIdent

String

null

Structure identifier in the schema for flat file schemas. Required when parsing a structure definition if the schema includes multiple structure definitions.

trimValues

Boolean

false

Trim values that are longer than the width of a field.

Valid values are true or false.

truncateDependingOn

Boolean

false

For COBOL copybook, truncates DEPENDING ON values to the length used.

Valid values are true or false.

useMissCharAsDefaultForFill

Boolean

false

By default, the flat file reader and writer use spaces for missing characters and ignore the setting of the missingValues property. When you set this property to true, DataWeave honors the setting of the missingValues property. Introduced in DataWeave 2.3 (2.3.0-20210823) for the September 2021 release of Mule 4.3.0-20210823.

Valid values are true or false.

zonedDecimalStrict

Boolean

false

For COBOL copybook, uses the 'strict' ASCII form of sign encoding for zoned decimal values.

Valid values are true or false.

Supported MIME Types

This format supports the following MIME types.

MIME Type

*/flatfile