azure-ai-document-intelligence-dotnet

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# Azure.AI.DocumentIntelligence (.NET)

Extract text, tables, and structured data from documents using prebuilt and custom models.

## Installation

```bash
dotnet add package Azure.AI.DocumentIntelligence
dotnet add package Azure.Identity
```

**Current Version**: v1.0.0 (GA)

## Environment Variables

```bash
DOCUMENT_INTELLIGENCE_ENDPOINT=https://<resource-name>.cognitiveservices.azure.com/  # Required: Document Intelligence endpoint
DOCUMENT_INTELLIGENCE_API_KEY=<your-api-key>  # Only required for AzureKeyCredential auth
BLOB_CONTAINER_SAS_URL=https://<storage>.blob.core.windows.net/<container>?<sas-token>  # Optional: blob container SAS URL for training data
AZURE_TOKEN_CREDENTIALS=prod  # Required only if DefaultAzureCredential is used in production
```

## Authentication

### Microsoft Entra Token Credential

```csharp
using Azure.Identity;
using Azure.AI.DocumentIntelligence;

string endpoint = Environment.GetEnvironmentVariable("DOCUMENT_INTELLIGENCE_ENDPOINT");
// Local dev: DefaultAzureCredential. Production: set AZURE_TOKEN_CREDENTIALS=prod or AZURE_TOKEN_CREDENTIALS=<specific_credential>
var credential = new DefaultAzureCredential(
    DefaultAzureCredential.DefaultEnvironmentVariableName
);
// Or use a specific credential directly in production:
// See https://learn.microsoft.com/dotnet/api/overview/azure/identity-readme?view=azure-dotnet#credential-classes
// var credential = new ManagedIdentityCredential();
var client = new DocumentIntelligenceClient(new Uri(endpoint), credential);
```

> **Note**: Entra ID requires a **custom subdomain** (e.g., `https://<resource-name>.cognitiveservices.azure.com/`), not a regional endpoint.

### API Key

```csharp
string endpoint = Environment.GetEnvironmentVariable("DOCUMENT_INTELLIGENCE_ENDPOINT");
string apiKey = Environment.GetEnvironmentVariable("DOCUMENT_INTELLIGENCE_API_KEY");
var client = new DocumentIntelligenceClient(new Uri(endpoint), new AzureKeyCredential(apiKey));
```

## Client Types

| Client | Purpose |
|--------|---------|
| `DocumentIntelligenceClient` | Analyze documents, classify documents |
| `DocumentIntelligenceAdministrationClient` | Build/manage custom models and classifiers |

## Prebuilt Models

| Model ID | Description |
|----------|-------------|
| `prebuilt-read` | Extract text, languages, handwriting |
| `prebuilt-layout` | Extract text, tables, selection marks, structure |
| `prebuilt-invoice` | Extract invoice fields (vendor, items, totals) |
| `prebuilt-receipt` | Extract receipt fields (merchant, items, total) |
| `prebuilt-idDocument` | Extract ID document fields (name, DOB, address) |
| `prebuilt-businessCard` | Extract business card fields |
| `prebuilt-tax.us.w2` | Extract W-2 tax form fields |
| `prebuilt-healthInsuranceCard.us` | Extract health insurance card fields |

## Core Workflows

### 1. Analyze Invoice

```csharp
using Azure.AI.DocumentIntelligence;

Uri invoiceUri = new Uri("https://example.com/invoice.pdf");

Operation<AnalyzeResult> operation = await client.AnalyzeDocumentAsync(
    WaitUntil.Completed, 
    "prebuilt-invoice", 
    invoiceUri);

AnalyzeResult result = operation.Value;

foreach (AnalyzedDocument document in result.Documents)
{
    if (document.Fields.TryGetValue("VendorName", out DocumentField vendorNameField)
        && vendorNameField.FieldType == DocumentFieldType.String)
    {
        string vendorName = vendorNameField.ValueString;
        Console.WriteLine($"Vendor Name: '{vendorName}', confidence: {vendorNameField.Confidence}");
    }

    if (document.Fields.TryGetValue("InvoiceTotal", out DocumentField invoiceTotalField)
        && invoiceTotalField.FieldType == DocumentFieldType.Currency)
    {
        CurrencyValue invoiceTotal = invoiceTotalField.ValueCurrency;
        Console.WriteLine($"Invoice Total: '{invoiceTotal.CurrencySymbol}{invoiceTotal.Amount}'");
    }
    
    // Extract line items
    if (document.Fields.TryGetValue("Items", out DocumentField itemsField)
        && itemsField.FieldType == DocumentFieldType.List)
    {
        foreach (DocumentField item in itemsField.ValueList)
        {
            var itemFields = item.ValueDictionary;
            if (itemFields.TryGetValue("Description", out DocumentField descField))
                Console.WriteLine($"  Item: {descField.ValueString}");
        }
    }
}
```

### 2. Extract Layout (Text, Tables, Structure)

From JantonioFC/skillsbank, MIT.