MTG

I exported the Standard Penny collection from Moxfield to JSON using a Python script:

import csv
import json

input_csv = 'moxfield_haves_2025-10-21-1123Z.csv'
output_json = 'standard_penny.json'

sets = set()
cards = []

with open(input_csv, newline='', encoding='utf-8') as csvfile:
    reader = csv.DictReader(csvfile)
    for row in reader:
        name = row.get('Name')
        edition = row.get('Edition')
        if name:
            cards.append(name)
        if edition:
            sets.add(edition.upper())

sets = sorted(list(sets))

output_data = {
    "sets": sets,
    "cards": cards
}

with open(output_json, 'w', encoding='utf-8') as jsonfile:
    json.dump(output_data, jsonfile, indent=2)

print(f"JSON saved to {output_json}")

I saved the JSON file as validator/formats/standardpenny.json and added it to the validator’s config:

{ "name": "Standard Penny", "key": "standardpenny", "datafile":"formats/standardpenny.json" },

Then I tried to validate this deck exported as Plain Text from Moxfield and got the error.