inventory application for ECE2524 Intro to UNIX
Python
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README.md
inventory.py

README.md

Inventory

This is a simple program to keep track of an inventory database. It reads commands from stdin, and updates a database file specified on the command line.

Features

Extra credit features implemented:

  • Sort on quantity works numerically.
  • Remove works with a pattern that can be applied to any field (or multiple fields)

In addition, multiple values can be updated with only one command (with the same pattern-matching syntax as works with delete), and the output can be sorted down to the minutest detail (you can specify an arbitrary number of fields to sort by, in preferential order).

Data storage design

The database files are composed of JSON objects, separated by newlines:

{"part-id":"a123","footprint":"dip6","description":"Digital IMU","quantity":4}
{"part-id":"a124","footprint":"dip6","description":"Digital IMU","quantity":4}

Protocol design

Most communication is done in JSON. To add a part, you must specify all fields in a JSON object, similar to what appears in the database file. Additional fields will be stored, for the sake of forward-compatibility, but queries against unspecified fields (for example, a "cost" field) will return an error.

The following commands are supported:

add <full JSON object>
remove <match pattern>
change <match pattern> <modification>
list [match pattern] [sort specification]

Match patterns are partial JSON objects. All three of the following match the above-specified part:

{"part-id":"a123"}
{"footprint":"dip6"}
{"part-id":"a123", "footprint":"dip6"}

The empty match pattern, {}, matches everything.

Modifications are basically identical to match patterns. The following command would change the description of the above-specified part to "This is a digital IMU with I2C".

 change {"part-id":"a123"} {"description":"This is a digital IMU with I2C"}

Sort specifications are JSON lists of field names, which order the output preferentially. If, for example, you want to rank by quantity and then by part number, this sort specification would do it for you:

 ["quantity", "part-id"]

Lists are returned as whitespace-separated fields for readability. They are separated by %%\ns.

Successful requests with no return value will return an OK\n.

Warning conditions are prefixed with the string "Warning:", and Errors are prefixed with the string "Error:".