git-history 0.1

Tools for analyzing Git history using SQLite

git-history

Tools for analyzing Git history using SQLite

Installation

Install this tool using pip:

$ pip install git-history

Usage

The file command analyzes the history of an individual file.

This assumes you have a JSON file that consists of an array of objects, and that has multiple versions stored away in the Git history, likely through Git scraping.

Most basic usage is:

git-convert file database.db filename.json

This will create a new SQLite database in the database.db file with two tables:

• commits containing a row for every commit, with a hash column and the commit_at date.
• items containing a row for every item in every version of the filename.json file - with an extra commit column that is a foreign key back to the commits table.

More interesting is if you specify columns to be treated as IDs within that data, using the --id option one or more times. This allows the tool to track versions of each item as they change over time.

git-convert file database.db filename.json --id IncidentID

If you do this, three tables will be created - commits, items and item_versions.

The items table will contain just the most recent version of each row, de-duplicated by ID.

The item_versions table will contain a row for each captured differing version of that item, plus the following columns:

• item as a foreign key to the items table
• commit as a foreign key to the commits table
• version as the numeric version number, starting at 1 and incrementing for each captured version

If you have already imported history, the command will skip any commits that it has seen already and just process new ones. This means that even though an initial import could be slow subsequent imports should run a lot faster.

Additional options:

• --repo DIRECTORY - the path to the Git repository, if it is not the current working directory.
• --branch TEXT - the Git branch to analyze - defaults to main.
• --id TEXT - as described above: pass one or more columns that uniquely identify a record, so that changes to that record can be calculated over time.
• --ignore TEXT - one or more columns to ignore - they will not be included in the resulting database.
• --convert TEXT - custom Python code for a conversion, see below.
• --import TEXT - Python modules to import for --convert.
• --ignore-duplicate-ids - if a single version of a file has the same ID in it more than once, the tool will exit with an error. Use this option to ignore this and instead pick just the first of the two duplicates.

Custom conversions using --convert

This tool expects each version of the stored file to be a JSON file that looks something like this:

[
    {
        "id": "552",
        "name": "Hawthorne Fire",
        "engines": 3
    },
    {
        "id": "556",
        "name": "Merlin Fire",
        "engines": 1
    }
]

If your data does not fit this shape, you can still use this tool to analyze it by writing a snippet of Python code that converts each stored file content into a Python list of dictionaries.

For example, if your stored files each look like this:

{
    "incidents": [
        {
            "id": "552",
            "name": "Hawthorne Fire",
            "engines": 3
        },
        {
            "id": "556",
            "name": "Merlin Fire",
            "engines": 1
        }
    ]
}

You could use the following Python snippet to convert them to the required format:

json.loads(content)["incidents"]

(The json module is exposed to your custom function by default.)

You would run the tool like this:

git-convert file database.db incidents.json \
  --id id \
  --convert 'json.loads(content)["incidents"]'

If you need to import additional modules you can do so with --import, for example:

git-history file trees.db ../sf-tree-history/Street_Tree_List.csv \
  --repo ../sf-tree-history \
  --import csv \
  --import io \
  --convert 'list(csv.DictReader(io.StringIO(content.decode("utf-8"))))' \
  --id TreeID

Development

To contribute to this tool, first checkout the code. Then create a new virtual environment:

cd git-history
python -m venv venv
source venv/bin/activate

Or if you are using pipenv:

pipenv shell

Now install the dependencies and test dependencies:

pip install -e '.[test]'

To run the tests:

pytest