azure-cosmos-ts

What this skill does

# @azure/cosmos (TypeScript/JavaScript)

Data plane SDK for Azure Cosmos DB NoSQL API operations — CRUD on documents, queries, bulk operations.

> **⚠️ Data vs Management Plane**
> - **This SDK (@azure/cosmos)**: CRUD operations on documents, queries, stored procedures
> - **Management SDK (@azure/arm-cosmosdb)**: Create accounts, databases, containers via ARM

## Installation

```bash
npm install @azure/cosmos @azure/identity
```

**Current Version**: 4.9.0  
**Node.js**: >= 20.0.0

## Environment Variables

```bash
COSMOS_ENDPOINT=https://<account>.documents.azure.com:443/
COSMOS_DATABASE=<database-name>
COSMOS_CONTAINER=<container-name>
# For key-based auth only (prefer AAD)
COSMOS_KEY=<account-key>
```

## Authentication

### AAD with DefaultAzureCredential (Recommended)

```typescript
import { CosmosClient } from "@azure/cosmos";
import { DefaultAzureCredential } from "@azure/identity";

const client = new CosmosClient({
  endpoint: process.env.COSMOS_ENDPOINT!,
  aadCredentials: new DefaultAzureCredential(),
});
```

### Key-Based Authentication

```typescript
import { CosmosClient } from "@azure/cosmos";

// Option 1: Endpoint + Key
const client = new CosmosClient({
  endpoint: process.env.COSMOS_ENDPOINT!,
  key: process.env.COSMOS_KEY!,
});

// Option 2: Connection String
const client = new CosmosClient(process.env.COSMOS_CONNECTION_STRING!);
```

## Resource Hierarchy

```
CosmosClient
└── Database
    └── Container
        ├── Items (documents)
        ├── Scripts (stored procedures, triggers, UDFs)
        └── Conflicts
```

## Core Operations

### Database & Container Setup

```typescript
const { database } = await client.databases.createIfNotExists({
  id: "my-database",
});

const { container } = await database.containers.createIfNotExists({
  id: "my-container",
  partitionKey: { paths: ["/partitionKey"] },
});
```

### Create Document

```typescript
interface Product {
  id: string;
  partitionKey: string;
  name: string;
  price: number;
}

const item: Product = {
  id: "product-1",
  partitionKey: "electronics",
  name: "Laptop",
  price: 999.99,
};

const { resource } = await container.items.create<Product>(item);
```

### Read Document

```typescript
const { resource } = await container
  .item("product-1", "electronics") // id, partitionKey
  .read<Product>();

if (resource) {
  console.log(resource.name);
}
```

### Update Document (Replace)

```typescript
const { resource: existing } = await container
  .item("product-1", "electronics")
  .read<Product>();

if (existing) {
  existing.price = 899.99;
  const { resource: updated } = await container
    .item("product-1", "electronics")
    .replace<Product>(existing);
}
```

### Upsert Document

```typescript
const item: Product = {
  id: "product-1",
  partitionKey: "electronics",
  name: "Laptop Pro",
  price: 1299.99,
};

const { resource } = await container.items.upsert<Product>(item);
```

### Delete Document

```typescript
await container.item("product-1", "electronics").delete();
```

### Patch Document (Partial Update)

```typescript
import { PatchOperation } from "@azure/cosmos";

const operations: PatchOperation[] = [
  { op: "replace", path: "/price", value: 799.99 },
  { op: "add", path: "/discount", value: true },
  { op: "remove", path: "/oldField" },
];

const { resource } = await container
  .item("product-1", "electronics")
  .patch<Product>(operations);
```

## Queries

### Simple Query

```typescript
const { resources } = await container.items
  .query<Product>("SELECT * FROM c WHERE c.price < 1000")
  .fetchAll();
```

### Parameterized Query (Recommended)

```typescript
import { SqlQuerySpec } from "@azure/cosmos";

const querySpec: SqlQuerySpec = {
  query: "SELECT * FROM c WHERE c.partitionKey = @category AND c.price < @maxPrice",
  parameters: [
    { name: "@category", value: "electronics" },
    { name: "@maxPrice", value: 1000 },
  ],
};

const { resources } = await container.items
  .query<Product>(querySpec)
  .fetchAll();
```

### Query with Pagination

```typescript
const queryIterator = container.items.query<Product>(querySpec, {
  maxItemCount: 10, // Items per page
});

while (queryIterator.hasMoreResults()) {
  const { resources, continuationToken } = await queryIterator.fetchNext();
  console.log(`Page with ${resources?.length} items`);
  // Use continuationToken for next page if needed
}
```

### Cross-Partition Query

```typescript
const { resources } = await container.items
  .query<Product>(
    "SELECT * FROM c WHERE c.price > 500",
    { enableCrossPartitionQuery: true }
  )
  .fetchAll();
```

## Bulk Operations

### Execute Bulk Operations

```typescript
import { BulkOperationType, OperationInput } from "@azure/cosmos";

const operations: OperationInput[] = [
  {
    operationType: BulkOperationType.Create,
    resourceBody: { id: "1", partitionKey: "cat-a", name: "Item 1" },
  },
  {
    operationType: BulkOperationType.Upsert,
    resourceBody: { id: "2", partitionKey: "cat-a", name: "Item 2" },
  },
  {
    operationType: BulkOperationType.Read,
    id: "3",
    partitionKey: "cat-b",
  },
  {
    operationType: BulkOperationType.Replace,
    id: "4",
    partitionKey: "cat-b",
    resourceBody: { id: "4", partitionKey: "cat-b", name: "Updated" },
  },
  {
    operationType: BulkOperationType.Delete,
    id: "5",
    partitionKey: "cat-c",
  },
  {
    operationType: BulkOperationType.Patch,
    id: "6",
    partitionKey: "cat-c",
    resourceBody: {
      operations: [{ op: "replace", path: "/name", value: "Patched" }],
    },
  },
];

const response = await container.items.executeBulkOperations(operations);

response.forEach((result, index) => {
  if (result.statusCode >= 200 && result.statusCode < 300) {
    console.log(`Operation ${index} succeeded`);
  } else {
    console.error(`Operation ${index} failed: ${result.statusCode}`);
  }
});
```

## Partition Keys

### Simple Partition Key

```typescript
const { container } = await database.containers.createIfNotExists({
  id: "products",
  partitionKey: { paths: ["/category"] },
});
```

### Hierarchical Partition Key (MultiHash)

```typescript
import { PartitionKeyDefinitionVersion, PartitionKeyKind } from "@azure/cosmos";

const { container } = await database.containers.createIfNotExists({
  id: "orders",
  partitionKey: {
    paths: ["/tenantId", "/userId", "/sessionId"],
    version: PartitionKeyDefinitionVersion.V2,
    kind: PartitionKeyKind.MultiHash,
  },
});

// Operations require array of partition key values
const { resource } = await container.items.create({
  id: "order-1",
  tenantId: "tenant-a",
  userId: "user-123",
  sessionId: "session-xyz",
  total: 99.99,
});

// Read with hierarchical partition key
const { resource: order } = await container
  .item("order-1", ["tenant-a", "user-123", "session-xyz"])
  .read();
```

## Error Handling

```typescript
import { ErrorResponse } from "@azure/cosmos";

try {
  const { resource } = await container.item("missing", "pk").read();
} catch (error) {
  if (error instanceof ErrorResponse) {
    switch (error.code) {
      case 404:
        console.log("Document not found");
        break;
      case 409:
        console.log("Conflict - document already exists");
        break;
      case 412:
        console.log("Precondition failed (ETag mismatch)");
        break;
      case 429:
        console.log("Rate limited - retry after:", error.retryAfterInMs);
        break;
      default:
        console.error(`Cosmos error ${error.code}: ${error.message}`);
    }
  }
  throw error;
}
```

## Optimistic Concurrency (ETags)

```typescript
// Read with ETag
const { resource, etag } = await container
  .item("product-1", "electronics")
  .read<Product>();

if (resource && etag) {
  resource.price = 899.99;
  
  try {
    // Replace only if ETag matches
    await container.item("product-1", "electronics").replace(resource, {
      accessCondition: { type: "IfMatch", condition: etag },
    });
  } catch (error) {
    if (error inst