Project 2 — Intermediate

Invoice Processing Bot (PDF se ERP tak)

AP team ko roz 200 invoices milte hain — PDF, email me. Har invoice ka data manually ERP me type karna. Is project me bot banayenge jo email se invoice nikaale, data extract kare, aur ERP entry ke liye ready kare.

Project kya karega?

Step-by-step build

Main.xaml (Sequence)
 |
 +-- Try Catch
 |    +-- Sequence: Fetch Invoices
 |    |    +-- Get Outlook Mail Messages
 |    |    |     Filter: "[SubjectContains]='invoice' AND [Unread]=true"
 |    |    |     -> dtMails
 |    |    +-- For Each  mail in dtMails
 |    |         +-- Sequence: Process One Mail
 |    |              +-- Save Attachments  mail  to  "C:\Invoices\"
 |    |              +-- For Each File: "C:\Invoices\*.pdf" -> pdfFile
 |    |                   +-- Read PDF Text  pdfFile  ->  strText
 |    |                   +-- Assign: invNo   = Regex.Match(strText,"INV-\d{6}").Value
 |    |                   +-- Assign: invDate = Regex.Match(strText,"\d{2}-\d{2}-\d{4}").Value
 |    |                   +-- Assign: total   = Regex.Match(strText,"Total[:\s]*[\d,\.]+").Value
 |    |                   +-- Assign: gst     = Regex.Match(strText,"\d{2}[A-Z]{5}\d{4}[A-Z]\d[A-Z\d][A-Z\d]").Value
 |    |                   +-- If  invNo <> ""  AND  total <> ""
 |    |                        +-- Write Row: [invNo, invDate, gst, total, "OK"]
 |    |                   +-- Else
 |    |                        +-- Write Row: [pdfFile.Name, "", "", "", "REVIEW"]
 |    |              +-- Mark mail as read
 |    +-- Catch (Exception)
 |         +-- Log Message  LogLevel.Error  ex.ToString

Regex se data nikalna

Har field ka apna pattern. Config.xlsx me rakho — vendor ke hisaab se badalna padta hai:

# Config.xlsx - Regex Patterns
Field        Pattern
InvoiceNo    INV-\d{6}
Date         \d{2}-\d{2}-\d{4}
GSTNo        \d{2}[A-Z]{5}\d{4}[A-Z]\d[A-Z\d][A-Z\d]
Total        Total[:\s]*[\d,\.]+

# UiPath me: Assign activity + Regex.Match(strText, pattern).Value
# Agar match fail = Value "" -> REVIEW row me daal do, row fail mat karo

Ye rule-based extraction hai. Agar har vendor ka template alag hai (fonts, layouts), to UiPath Document Understanding use hota hai — ML Extractor + Keyword Extractor + Form Extractor ka ensemble, jo confidence score deta hai. DU ka validation station me human approve karta hai low-confidence fields.

Error handling

• Scanned PDF (image): Read PDF Text khaali dega — OCR engine (IntelligentOCR) chahiye. DU me ye automatic hai.
• Wrong total: Regex ne "Total" ki jagah "Subtotal" pakad liya — pattern me word boundary lagao, aur total vs subtotal ka sanity check (total >= subtotal) lo.
• Duplicate invoice: Tracker Excel me invoice number pehle se hai? Check karke skip — vendor ko dobara pay karne ka risk.

# Duplicate check - Invoke Code (LINQ) ya simple loop:
If  dtTracker.AsEnumerable.Any(Function(r) r("InvoiceNo").ToString = invNo)
     +-- Log Message  LogLevel.Warning  "Duplicate: " + invNo
     +-- Continue For Each

Enterprise tips

• Invoices ko Orchestrator Queue me daalo (Dispatcher pattern) — alag Performer bot process karega. Scale kar sakte ho 10 robots tak.
• Low-confidence invoices Action Center task me bhejo — human approve kare, bot phir process karega. Ye DU + Action Center ka standard flow hai.
• Processed PDFs ko archive folder me move karo with date subfolder — audit ke liye zaroori.
• GST number ka regex 15-char format validate karo — fake invoices ka pehla filter yahi hai.

Exercise

Common mistakes

• Har mail ko process karna: Subject filter lagao — support@ ki sab mails me invoice nahi hota.
• Regex hardcode: Config.xlsx me rakho — vendor template badalta hai, bot redeploy nahi karna padega.
• Duplicate payment risk: Invoice number uniqueness check na karna = seedha paisa ka nuksaan.
• OCR pe blind trust: OCR 100% accurate nahi — total amount ka cross-check zaroori hai.