zeus
110 lines
2.6 KiB
Markdown
110 lines
2.6 KiB
Markdown
# ``GRDB/Configuration``
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The configuration of a database connection.
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## Overview
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You create a `Configuration` before opening a database connection:
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```swift
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var config = Configuration()
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config.readonly = true
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config.maximumReaderCount = 2 // (DatabasePool only) The default is 5
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let dbQueue = try DatabaseQueue( // or DatabasePool
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path: "/path/to/database.sqlite",
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configuration: config)
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```
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See <doc:DatabaseConnections>.
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## Frequent Use Cases
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#### Tracing SQL Statements
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You can setup a tracing function that prints out all executed SQL requests with ``prepareDatabase(_:)`` and ``Database/trace(options:_:)``:
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```swift
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var config = Configuration()
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config.prepareDatabase { db in
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db.trace { print("SQL> \($0)") }
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}
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let dbQueue = try DatabaseQueue(
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path: "/path/to/database.sqlite",
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configuration: config)
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// Prints "SQL> SELECT COUNT(*) FROM player"
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let playerCount = dbQueue.read { db in
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try Player.fetchCount(db)
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}
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```
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#### Public Statement Arguments
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Debugging is easier when database errors and tracing functions expose the values sent to the database. Since those values may contain sensitive information, verbose logging is disabled by default. You turn it on with ``publicStatementArguments``:
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```swift
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var config = Configuration()
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#if DEBUG
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// Protect sensitive information by enabling
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// verbose debugging in DEBUG builds only.
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config.publicStatementArguments = true
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#endif
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let dbQueue = try DatabaseQueue(
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path: "/path/to/database.sqlite",
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configuration: config)
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do {
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try dbQueue.write { db in
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user.name = ...
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user.location = ...
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user.address = ...
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user.phoneNumber = ...
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try user.save(db)
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}
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} catch {
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// Prints sensitive information in debug builds only
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print(error)
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}
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```
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> Warning: It is your responsibility to prevent sensitive information from leaking in unexpected locations, so you should not set the `publicStatementArguments` flag in release builds (think about GDPR and other privacy-related rules).
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## Topics
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### Creating a Configuration
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- ``init()``
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### Configuring SQLite Connections
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- ``acceptsDoubleQuotedStringLiterals``
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- ``busyMode``
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- ``foreignKeysEnabled``
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- ``journalMode``
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- ``readonly``
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- ``JournalModeConfiguration``
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### Configuring GRDB Connections
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- ``allowsUnsafeTransactions``
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- ``defaultTransactionKind``
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- ``label``
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- ``maximumReaderCount``
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- ``observesSuspensionNotifications``
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- ``persistentReadOnlyConnections``
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- ``prepareDatabase(_:)``
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- ``publicStatementArguments``
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- ``transactionClock``
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- ``TransactionClock``
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### Configuring the Quality of Service
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- ``qos``
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- ``readQoS``
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- ``writeQoS``
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- ``targetQueue``
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- ``writeTargetQueue``
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