Cloudbase Document Database Web Sdk

Query Operators

CloudBase provides query operators via db.command (aliased as _):

• _.gt(value) - Greater than
• _.gte(value) - Greater than or equal
• _.lt(value) - Less than
• _.lte(value) - Less than or equal
• _.eq(value) - Equal to
• _.neq(value) - Not equal to
• _.in(array) - Value in array
• _.nin(array) - Value not in array

Basic Operations

Query Single Document

Query by document ID:

const result = await db.collection('todos')
    .doc('docId')
    .get();

Query Multiple Documents

Query with conditions:

const result = await db.collection('todos')
    .where({
        completed: false,
        priority: 'high'
    })
    .get();

Note: get() returns 100 records by default, maximum 1000.

Query Methods Chaining

Combine methods for complex queries:

• .where(conditions) - Filter conditions
• .orderBy(field, direction) - Sort by field ('asc' or 'desc')
• .limit(number) - Limit results (default 100, max 1000)
• .skip(number) - Skip records for pagination
• .field(object) - Specify fields to return (true/false)

Advanced Features

For detailed information on specific topics, refer to:

CRUD Operations

See ./crud-operations.md for:

• Creating documents (add, batch add)
• Updating documents (partial updates, operators)
• Deleting documents (conditional delete, soft delete)
• Complete CRUD manager examples

Complex Queries

See ./complex-queries.md for:

• Using query operators
• Combining multiple conditions
• Field selection
• Sorting and limiting results

Pagination

See ./pagination.md for:

• Implementing page-based navigation
• Calculating skip and limit values
• Cursor-based pagination
• Infinite scroll patterns

Aggregation Queries

See ./aggregation.md for:

• Grouping data
• Statistical calculations
• Pipeline operations
• Time-based aggregations

Geolocation Queries

See ./geolocation.md for:

• Proximity searches
• Area-based queries
• Geographic indexing requirements
• Distance-based features

Realtime Database

See ./realtime.md for:

• Real-time data synchronization using watch() method
• Setting up listeners for document changes
• Handling real-time updates in chat and collaboration apps
• Performance optimization and error handling
• Common patterns for real-time applications

Security Rules

See ./security-rules.md for:

• Configuring database permissions
• Simple permissions vs custom rules
• Permission categories and usage
• Security rule syntax and examples

Common Patterns

Error Handling

Always wrap database operations in try-catch:

try {
    const result = await db.collection('todos').get();
    console.log(result.data);
} catch (error) {
    console.error('Database error:', error);
}

Return Value Structure

Database operations return:

{
    data: [...], // Array of documents
    // Additional metadata
}

Important Notes

1. Environment ID: Replace "your-env-id" with actual CloudBase environment ID
2. Default Limits: get() returns 100 records by default
3. Collection Names: Use string literals for collection names
4. Geolocation Index: Geographic queries require proper indexing
5. Async/Await: All database operations are asynchronous

Best Practices

1. Initialize SDK once at application startup
2. Reuse database instance across the application
3. Use query operators for complex conditions
4. Implement pagination for large datasets
5. Select only needed fields to reduce data transfer
6. Handle errors appropriately
7. Create indexes for frequently queried fields

Coding Rules

• It is HIGHLY RECOMMENDED to have a type definition and model layer for each collection in your document database. This will help you to avoid errors and make your code more robust. That would be the single source of truth for your database schema. Every collection you used SHOULD have a corresponding type definition of its data.
• Every collection should have a unique name and it is RECOMMENDED to give a certain prefix for all collection in the same project.
• Collections should have well defined and meaningful security rules(policy) for create, read, write and delete permission according to the business logic. Details refer to ./security-rules.md. When writing expressions in security rules, The type definition of the collection mention above can be used as the type reference.

Quick Reference

Common query examples:

// Simple query
db.collection('todos').where({ status: 'active' }).get()

// With operators
db.collection('users').where({ age: _.gt(18) }).get()

// Pagination
db.collection('posts')
    .orderBy('createdAt', 'desc')
    .skip(20)
    .limit(10)
    .get()

// Field selection
db.collection('users')
    .field({ name: true, email: true, _id: false })
    .get()

For more detailed examples and advanced usage patterns, refer to the companion reference files in this directory.

Error handling

EVERY database operation(including get(), add(), update(), delete() etc)should check the return value's code for any errors. For example:

const result = await db.collection('todos').add(newTodo);
if(typeof result.code === 'string') {
    // Handle error ...
}

Error MUST be handled with detail and human-readable message and friendly UI.