FlatFileWriter

Short Description

FlatFileWriter writes data to flat files. The output flat file can be in form of CSV (character separated values), fixed-length format or mixed-length format (combination of mixed-length and fixed-length formats).

The component supports partitioning, compression, writing to output port or to remote destination.

UniversalDataWriter is an alias for FlatFileWriter.

Ports

Metadata

FlatFileWriter does not propagate metadata.

The component has no metadata template.

FlatFileWriter requires string, byte or cbyte field in the output metadata.

FlatFileWriter Attributes

[1] Either both or neither of these attributes must be specified.

[2] Either both or neither of these attributes must be specified

Details

The type of formatting is specified in metadata for the input port data flow.

Appending to Files

Appending to files is supported, if you write data to:

• local files

• local zipped files

• remote files via smb protocol

Appending to files is not supported in, if you write data to:

• local gzipped files

• remote files via ftp protocol

• remote files via webdav protocol

• remote files via Amazon S3 protocol

• remote files via hdfs protocol

Null Values

Empty strings and null values are written to a file as empty strings.

Notes and Limitations

Field Size Limitation

FlatFileWriter can write fields of a size up to 4kB.

• To enable bigger fields to be written into a file, increase the DataFormatter.FIELD_BUFFER_LENGTH property, see Engine configuration. Increasing the size of this buffer does not cause any significant increase of the graph memory consumption.

• Another way to solve the issue with fields too big to be written is the utilization of the Normalizer component that can split large fields into several records.

Maps, Lists and Variants

FlatFileWriter cannot write maps, lists and variants. If you do not need a field with map, list or variant datatype in the output file, you can omit it using Exclude fields attribute. If you need to write the content of the map, list or variant field, convert the field into string using Map first.

Examples

Writing Records to File

Write records to a file objects.txt using FlatFileWriter. The input metadata fields are color, shape and material.

Solution

Use the File URL attribute to define a path to the file to be created.

An example of the output file, delimited input metadata:

gray|cylinder|steel
brown|cube|wood
transparent|sphere|glass

The separators "|" depend on metadata on the input edge.

An example of the output file, fixed input metadata:

gray           cylinder      steel
brown          cube          wood
transparent    sphere        glass

Producing Quoted Strings

Write data from the previous example to a file. Each field value has to be surrounded by a quote character ' (apostrophe).

Solution

Use the attributes File URL, Quoted strings and Quote character.

If a string to be quoted contains a quote character, the quote character in the string is doubled. E.g. o’clock is quoted as 'o''clock'.

Writing Records Without Delimiters

This example shows writing records without writing record delimiters.

You receive an output from XMLWriter in a streaming mode. The records have to be seamlessly written to the file. No delimiter should be written between the records.

Solution

The solution to the problem depends on metadata. The input metadata of FlatFileWriter must have no Record delimiter, no Default delimiter and must use EOF as delimiter.

In FlatFileWriter, enter File URL.

The records will be written without delimiters as no delimiters are specified in metadata.

Writing Fixed-Length Records to Output Port

Write several fields of fixed-length metadata into one field of the output port (provided one input record creates one output record).

Solution

Make sure that input metadata has no record delimiter set. Select metadata on the input edge and open the Edit Metadata window. Select the first row in the Record pane of the editor and make sure that the Record delimiter property is empty.

Create metadata on the output edge with a single field.

Use the attributes File URL and Records per file.

Best Practices

We recommend to explicitly specify encoding of the output file (with the Charset attribute). It ensures better portability of the graph across systems with different default encoding.

The recommended encoding is UTF-8.

See also

FlatFileWriter
UniversalDataReader
Common properties of components
Specific attribute types
Common Properties of Writers