target-mako

This is a Singer target that reads JSON-formatted data following the Singer spec.

This target uses Mako templating engine to generate output files containing the stream data.

This target

• loads the configured templates using Mako templating language
• write the configured header (if any) into each output files (Header uses the first record values)
• receive the streamed records
• for each record, write one block rendered from the template (using the record data) in each output file
• write the configured footer (if any) into each output files (Footer uses the last record values)

Sources on Github

Accessing data in templates:

• The record data can be used in the template with (Null/None values will be safely displayed as empty string)

    ${record.attribute.sub-attribute}
  

• The schema data can be used in the template with (Null/None values will be safely displayed as empty string)

    ${schema.attribute.sub-attribute}
  

• Some Internal data are provided by the target module:

  • record index is counting records starting from 0

      ${record.record_index}
    

  • Record number is counting records starting from 1

      ${record.record_number}
    

Formatting functions

Some formatting function exists to help create your templates

• Protect against Null (Python None) values

First parameter is the data to format (example: record.attribute.sub-attribute)

    ${functions['null_safe'](record.attribute.sub-attribute)}

• Specify a fixed size for strings

First parameter is the data to format (example: record.attribute.sub-attribute)

Second parameter is the required size (integer)

    ${functions['fixed_size'](record.attribute.sub-attribute, 27)}

• Specify a fixed size for strings (align left)

First parameter is the data to format (example: record.attribute.sub-attribute)

Second parameter is the required size (integer)

    ${functions['lfixed'](record.attribute.sub-attribute, 27)}

• Specify a fixed size for strings (align rigth)

First parameter is the data to format (example: record.attribute.sub-attribute)

Second parameter is the required size (integer)

    ${functions['rfixed'](record.attribute.sub-attribute, 27)}

• Specify a fixed size for numbers (by adding 0 before the passed value)

First parameter is the data to format (example: record.attribute.sub-attribute)

Second parameter is the required size (integer)

    ${functions['nfixed '](record.attribute.sub-attribute, 27)}

• JSON Date formatting

First parameter is the data to format (must be a JSON date YYYY-mm-dd)

Second parameter is the output format in Python date-time format

    ${functions['format_json_date'](record.attribute.sub-attribute,'%d%m%Y')}

• Date formatting

First parameter is the data to format

Second parameter is the input format in Python date-time format

Third parameter is the output format in Python date-time format

    ${functions['format_date'](record.attribute.sub-attribute, '%d/%m/%Y','%d%m%Y')}

• Lower letters

First parameter is the data to format

    ${functions['lower'](record.attribute.sub-attribute)}

• Upper letters

First parameter is the data to format

    ${functions['upper'](record.attribute.sub-attribute)}

Config file description:

Here is a sample config file:

   {
     "disable_collection": true,
     "cache_template_dir": "/temp/mako_modules",
     "template_dir": "../default-templates",
     "output_dir": "../default-output",
     "template_list": [
     ],
     "stream_configs": {
       "sample": {
         "template_dir": "../templates",
         "output_dir": "../output",
         "template_list": [
           {
             "header_template_name": "csv/sample_header.template.csv",
             "data_template_name": "csv/sample.template.csv",
             "footer_template_name": "",
             "output_file_name": "sample.csv",
             "output_file_encoding": "utf8",
             "output_file_EOL": "\r\n"
           },
           {
             "header_template_name": "json/sample_header.template.json",
             "data_template_name": "json/sample.template.json",
             "footer_template_name": "json/sample_footer.template.json",
             "output_file_name": "sample{record_index}.json",
             "output_file_encoding": "utf8",
             "output_file_EOL": "\r\n",
             "one_file_per_record": true
           },
       }
     }
   }

First part is "global configuration":

• "disable_collection" optional, to disable sending usage statistic to Singer platform.
• "cache_template_dir" path to directory that will be used to cache templates content for Mako engine.

Second part is default configuration for all streams:

• "template_dir" : path to the directory that contains the template files.
• "output_dir" : path to the directory that where the output files will be created.
• "template_list" : list of template for file generation. Each element of the list contains:
  • "header_template_name" : file name of the template file for header (can be empty).It is used once per stream at the beginning.
  • "data_template_name" : file name of the template file for record. It is used once per record in the stream.
  • "footer_template_name" : file name of the template file for footer (can be empty). It is used once at the end of the stream.
  • "output_file_name" : the name of the generated file (can contain variables in case of multiple file generation)
  • "output_file_encoding" : Optionnal the generated file encoding. Default value is "utf8". For possible value please refer to https://docs.python.org/3/library/io.html?highlight=newline#io.TextIOWrapper
  • "output_file_EOL" : Optionnal the generated file End Of Line. Default Value is "\r\n". For possible values please refer to https://docs.python.org/3/library/io.html?highlight=newline#io.TextIOWrapper
  • "one_file_per_record" : boolean, if true, the target will generate one file per record in the stream, else it will generate one file containing all records (repeating the "data_template_name").

Third part is stream specific configuration:

expected structure is:

   "stream_configs": {
       <stream-id1> : {},
       <stream-id2> : {}
   }

All values from second part (Default values) can be overridden for each stream.

---

Copyright © 2020 elebail