EVL – ETL Tool


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Table of Contents

Readjson

(since EVL 1.2)

Parse <f_in> into <evd>.

In general not all input fields need to exist in the input JSON, but if they are, then the option ‘--all-fields-exist’ will speed up the processing.

When the input JSON has not the same order of fields as defined in <evd>, then option ‘--match-fields’ has to be used.

Usually when reading JSON file written by ‘Writejson’, it is good to call ‘Readjson’ with option ‘-a’, as there are always all fields from <evd>.

Readjson

is to be used in EVS job structure definition file. <f_out> is either output file or flow name.

evl readjson

is intended for standalone usage, i.e. to be invoked from command line and and write to standard output.

EVD and EVS are EVL definition files, for details see evl-evd(5) and evl-evs(5).

Synopsis

Readjson
  <f_in> <f_out> (<evd>|-d <inline_evd>)
  [-a|--all-fields-exist] [-m|--match-fields] [-y|--text-output]

evl readjson
  (<evd>|-d <inline_evd>)
  [--all-fields-exist] [--match-fields] [-y|--text-output]
  [-v|--verbose]

evl readjson
  ( --help | --usage | --version )

Options

-d, --data-definition=<inline_evd>

either this option or the file <evd> must be presented. Example: -d ’user_sum long’

-a, --all-fields-exist

when the input contain all fields (e.g. output of evl-writejson), then using this option increase the performance

-m, --match-fields

when field are not in the same order as used in evd, this option must be used

-y, --text-output

write the output as text, not binary

Standard options:

--help

print this help and exit

--usage

print short usage information and exit

-v, --verbose

print to stderr info/debug messages of the component

--version

print version and exit

In general not all input fields need to exist in the input JSON, but if they are, then the option "–all-fields-exist" will speed up the processing.

When the input JSON has not the same order of fields as defined in "EVD" file, then option "–match-fields" has to be used.

Usually when reading file written by "EVL" component ‘Writejson’, it is good to call "Readjson" with option "-a", as there are always all fields from "EVD".