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Overview

The application maintains a processing history that tracks the last 10 file uploads, storing filenames, timestamps, and key statistics. History is stored in Flask sessions and survives between page refreshes.

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Core Function

History tracking is implemented in the salvar_historico() function from app.py:75: 
def salvar_historico(filename, stats):
    """Salva o histórico de processamentos na sessão"""
    hist = session.get('historico', [])
    hist.insert(0, {
        'arquivo': filename,
        'data': datetime.now().strftime('%d/%m/%Y %H:%M'),
        'encontrados': stats['filtrados'],
        'total': stats['total']
    })
    session['historico'] = hist[:10]

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How It Works

1

Retrieve Existing History

Fetches the current history list from Flask session, defaulting to empty list if none exists:
hist = session.get('historico', [])
2

Create New Entry

Constructs a dictionary with file metadata and statistics:
{
    'arquivo': filename,
    'data': datetime.now().strftime('%d/%m/%Y %H:%M'),
    'encontrados': stats['filtrados'],
    'total': stats['total']
}
3

Insert at Beginning

Uses hist.insert(0, ...) to add the new entry at the start (most recent first)
4

Limit to 10 Entries

Slices the list to keep only the most recent 10 items:
session['historico'] = hist[:10]

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History Entry Structure

Each history entry contains exactly 4 fields: 
{
    'arquivo': 'relatorio_auvo_2024.csv',     # Original filename
    'data': '15/03/2024 14:32',                # Processing timestamp
    'encontrados': 147,                        # Filtered task count
    'total': 1523                              # Total records in file
}

arquivo

Original uploaded filename (preserved as-is)

data

Brazilian date/time format (DD/MM/YYYY HH:MM)

encontrados

Number of tasks matching filter keywords

total

Total records in the uploaded file

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Integration in Upload Flow

History is saved automatically during file processing in the /upload route: 
# From app.py:156
df_original, resultado_final = processar_arquivo(file, palavras_chave)
stats = gerar_estatisticas(df_original, resultado_final, palavras_chave)

# ... other processing ...

salvar_historico(file.filename, stats)  # History saved here
History is saved after successful processing but before rendering results. This ensures only successfully processed files appear in history.

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Viewing History

The history is accessible via the /historico route: 
# From app.py:118
@app.route('/historico')
def historico():
    hist = session.get('historico', [])
    return render_template('historico.html', historico=hist)

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Template Integration

The history list is passed to historico.html as the historico variable, which can iterate over entries: 
<!-- Example template usage -->
{% for entry in historico %}
  <div class="history-item">
    <strong>{{ entry.arquivo }}</strong><br>
    Processado em: {{ entry.data }}<br>
    Encontrados: {{ entry.encontrados }} de {{ entry.total }}
  </div>
{% endfor %}

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Storage Mechanism

  • Backend: Flask’s session system (signed cookies by default)
  • Encryption: Signed with SECRET_KEY from environment variables
  • Persistence: Survives page refreshes and navigation
  • Lifetime: Expires when browser closes (unless SESSION_PERMANENT is set)
  • Size limit: Typically 4KB for cookie-based sessions
  • Security: Not visible/modifiable by clients without the secret key

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Date Formatting

Timestamps use Brazilian Portuguese format: 
datetime.now().strftime('%d/%m/%Y %H:%M')
CodeMeaningExample
%dDay (zero-padded)09
%mMonth (zero-padded)03
%Y4-digit year2024
%HHour (24-hour, zero-padded)14
%MMinute (zero-padded)32
Output: 09/03/2024 14:32

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FIFO Queue Behavior

The history operates as a FIFO (First In, First Out) queue limited to 10 entries. When an 11th file is processed, the oldest entry is automatically removed.

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Example Sequence

# Initial state: 10 items
history = [file10, file9, file8, ..., file1]

# After processing file11:
history = [file11, file10, file9, ..., file2]  # file1 is dropped

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Statistics Extraction

Only two statistics are stored from the full stats dictionary: 
'encontrados': stats['filtrados'],  # Filtered count
'total': stats['total']             # Total count
The percentage (percentual) and per-keyword breakdown (por_palavra) are not stored in history to minimize session size. These can be recalculated from encontrados and total if needed.

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Use Cases

Audit Trail

Track which files have been processed and when

Quick Reference

See statistics from previous runs without reprocessing

Pattern Detection

Identify trends in task occurrence rates over time

Duplicate Prevention

Spot if the same file is being uploaded multiple times

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Limitations

  • History is per-browser session (not shared across users or devices)
  • History is cleared when the browser session ends
  • No database persistence - history doesn’t survive server restarts
  • Limited to 10 entries maximum
  • No way to delete individual entries (only cleared by session expiration)

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Edge Cases

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Empty History

If no files have been processed: 
hist = session.get('historico', [])  # Returns []
The template should handle empty lists gracefully: 
{% if historico %}
  <!-- Show history -->
{% else %}
  <p>Nenhum arquivo processado ainda.</p>
{% endif %}

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Identical Filenames

If the same filename is uploaded multiple times, each processing creates a separate history entry: 
[
  {'arquivo': 'relatorio.csv', 'data': '15/03/2024 15:00', ...},
  {'arquivo': 'relatorio.csv', 'data': '15/03/2024 14:30', ...},
  {'arquivo': 'relatorio.csv', 'data': '15/03/2024 14:00', ...}
]

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Future Enhancements

Potential improvements to the history system:
  • Database persistence for permanent history
  • User-specific history with authentication
  • Ability to re-run previous processing with same keywords
  • Export history to CSV/JSON
  • Detailed statistics including per-keyword breakdown
  • Filtering/searching within history

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