Terminal Methods

All queries must end with a terminal method to execute. These methods actually perform the query and return results.

Quick Navigation

• Quick Reference
• Detailed Examples
• Important Notes
• Common Patterns
• Related Topics

Quick Reference

Method	Description	Example
toArrayAsync()	Get all results as an array	await ctx.products.toArrayAsync()
firstAsync()	Get first item (throws if none)	await ctx.products.firstAsync()
firstOrUndefinedAsync()	Get first item or undefined	await ctx.products.firstOrUndefinedAsync()
someAsync()	Check if any items exist	await ctx.products.someAsync()
everyAsync(predicate)	Check if all items match	await ctx.products.everyAsync(p => p.inStock)
countAsync()	Count total items	await ctx.products.countAsync()
sumAsync(field)	Sum numeric field	await ctx.products.sumAsync(p => p.price)
minAsync(field)	Get minimum value	await ctx.products.minAsync(p => p.price)
maxAsync(field)	Get maximum value	await ctx.products.maxAsync(p => p.price)
distinctAsync()	Get unique values	await ctx.products.distinctAsync()
toGroupAsync(selector)	Group items by key	await ctx.products.toGroupAsync(p => p.category)
removeAsync()	Delete matching items	await ctx.products.removeAsync()

Detailed Examples

Getting All Results

// Get all products
const allProducts = await ctx.products.toArrayAsync();

// Get all products with filtering
const expensiveProducts = await ctx.products
  .where((p) => p.price > 100)
  .toArrayAsync();

Getting Single Items

// Get first product (throws if none exist)
const firstProduct = await ctx.products.firstAsync();

// Get first product or undefined if none exist
const firstOrUndefined = await ctx.products.firstOrUndefinedAsync();

// Get first expensive product
const firstExpensive = await ctx.products
  .where((p) => p.price > 100)
  .firstOrUndefinedAsync();

Checking Existence

// Check if any products exist
const hasProducts = await ctx.products.someAsync();

// Check if any expensive products exist
const hasExpensiveProducts = await ctx.products
  .where((p) => p.price > 100)
  .someAsync();

// Check if all products are in stock
const allInStock = await ctx.products.everyAsync((p) => p.inStock);

// Check if all electronics are in stock
const allElectronicsInStock = await ctx.products
  .where((p) => p.category === "electronics")
  .everyAsync((p) => p.inStock);

Counting Items

// Count all products
const totalCount = await ctx.products.countAsync();

// Count products in specific category
const electronicsCount = await ctx.products
  .where((p) => p.category === "electronics")
  .countAsync();

// Count expensive products
const expensiveCount = await ctx.products
  .where((p) => p.price > 100)
  .countAsync();

Aggregation Operations

// Sum all product prices
const totalValue = await ctx.products.sumAsync((p) => p.price);

// Sum prices of electronics
const electronicsValue = await ctx.products
  .where((p) => p.category === "electronics")
  .sumAsync((p) => p.price);

// Get minimum price
const minPrice = await ctx.products.minAsync((p) => p.price);

// Get maximum price
const maxPrice = await ctx.products.maxAsync((p) => p.price);

// Get minimum price of electronics
const minElectronicsPrice = await ctx.products
  .where((p) => p.category === "electronics")
  .minAsync((p) => p.price);

Distinct Values

// Get unique categories
const uniqueCategories = await ctx.products
  .map((p) => p.category)
  .distinctAsync();

// Get unique prices
const uniquePrices = await ctx.products.map((p) => p.price).distinctAsync();

// Get unique product names
const uniqueNames = await ctx.products.map((p) => p.name).distinctAsync();

Grouping Data

Group items by a key value, returning a record where keys are the grouped values and values are arrays of items with that key:

// Group products by category
const productsByCategory = await ctx.products.toGroupAsync((p) => p.category);
// Result: { "electronics": Product[], "clothing": Product[], "books": Product[] }

// Group products by status
const productsByStatus = await ctx.products.toGroupAsync((p) => p.status);
// Result: { "active": Product[], "inactive": Product[] }

// Group with filtering
const expensiveByCategory = await ctx.products
  .where((p) => p.price > 100)
  .toGroupAsync((p) => p.category);

// Group by numeric field
const productsByPriceRange = await ctx.products.toGroupAsync((p) =>
  p.price < 50 ? "budget" : p.price < 200 ? "mid" : "premium"
);
// Result: { "budget": Product[], "mid": Product[], "premium": Product[] }

The selector function must return a value that can be used as an object key (string, number, or Date). Each group contains an array of all items that share the same key value.

Removal Operations

// Remove all products
await ctx.products.removeAsync();

// Remove expensive products
await ctx.products.where((p) => p.price > 100).removeAsync();

// Remove products in specific category
await ctx.products.where((p) => p.category === "electronics").removeAsync();

// Remove out of stock products
await ctx.products.where((p) => p.inStock === false).removeAsync();

Important Notes

Lazy Evaluation

• Queries are lazy - nothing executes until you call a terminal method
• You can chain multiple operations before calling a terminal method
• The query is built up and executed only when the terminal method is called

Async vs Callback Styles

Both async Promises and callback styles are supported:

// Async style (recommended)
const products = await ctx.products.toArrayAsync();

// Callback style
ctx.products.toArray((result) => {
  if (result.ok === "success") {
    console.log("Products:", result.data);
  } else {
    console.error("Error:", result.error);
  }
});

Live Queries

For live results that update automatically, you can chain .subscribe() before a terminal method:

// Live query - will update when data changes
ctx.products
  .where((p) => p.price > 100)
  .subscribe()
  .toArrayAsync();

Common Patterns

Data Validation

// Check if user exists before creating
const userExists = await ctx.users.where((u) => u.email === email).someAsync();

if (userExists) {
  throw new Error("User already exists");
}

Pagination with Count

// Get page data and total count
const pageSize = 10;
const page = 1;
const offset = (page - 1) * pageSize;

const [products, totalCount] = await Promise.all([
  ctx.products.skip(offset).take(pageSize).toArrayAsync(),
  ctx.products.countAsync(),
]);

Conditional Operations

// Only proceed if data exists
const hasData = await ctx.products.someAsync();
if (hasData) {
  const firstProduct = await ctx.products.firstAsync();
  // Process first product
}

Organizing Data by Category

// Group products by category for display
const productsByCategory = await ctx.products.toGroupAsync((p) => p.category);

// Iterate over groups
for (const [category, products] of Object.entries(productsByCategory)) {
  console.log(`${category}: ${products.length} products`);
}

// Group with filtering
const activeProductsByStatus = await ctx.products
  .where((p) => p.active)
  .toGroupAsync((p) => p.status);

Related Topics

• Filtering Data - Filter before terminal methods
• Sorting Results - Sort before terminal methods
• Explain - Make terminals return { data, explanation }
• Aggregation - Aggregation terminal methods