schemachanger-part-2

.swiftlint.yml

@@ -3,6 +3,7 @@ disabled_rules: # rule identifiers to exclude from running
   - operator_whitespace
   - large_tuple
   - closure_parameter_position
+  - inclusive_language  # sqlite_master etc.
 included: # paths to include during linting. `--path` is ignored if present. takes precendence over `excluded`.
   - Sources
   - Tests

CHANGELOG.md

@@ -1,6 +1,7 @@
 0.14.0 (tbd), [diff][diff-0.14.0]
 ========================================
 
+* Support more complex schema changes and queries ([#1073][], [#1146][] [#1148][])
 * Support `ATTACH`/`DETACH` ([#30][], [#1142][])
 * Support `WITH` clause ([#1139][])
 * Add `Value` conformance for `NSURL` ([#1110][], [#1141][])
@@ -160,6 +161,7 @@
 [#866]: https://github.com/stephencelis/SQLite.swift/pull/866
 [#881]: https://github.com/stephencelis/SQLite.swift/pull/881
 [#919]: https://github.com/stephencelis/SQLite.swift/pull/919
+[#1073]: https://github.com/stephencelis/SQLite.swift/issues/1073
 [#1075]: https://github.com/stephencelis/SQLite.swift/pull/1075
 [#1077]: https://github.com/stephencelis/SQLite.swift/issues/1077
 [#1094]: https://github.com/stephencelis/SQLite.swift/pull/1094
@@ -185,3 +187,5 @@
 [#1141]: https://github.com/stephencelis/SQLite.swift/pull/1141
 [#1142]: https://github.com/stephencelis/SQLite.swift/pull/1142
 [#1144]: https://github.com/stephencelis/SQLite.swift/pull/1144
+[#1146]: https://github.com/stephencelis/SQLite.swift/pull/1146
+[#1148]: https://github.com/stephencelis/SQLite.swift/pull/1148

Documentation/Index.md

@@ -1371,6 +1371,37 @@ try db.transaction {
 
 > _Note:_ Transactions run in a serial queue.
 
+## Querying the Schema
+
+We can obtain generic information about objects in the current schema with a `SchemaReader`:
+
+```swift
+let schema = db.schema
+```
+
+To query the data:
+
+```swift
+let indexes = try schema.objectDefinitions(type: .index)
+let tables = try schema.objectDefinitions(type: .table)
+let triggers = try schema.objectDefinitions(type: .trigger)
+```
+
+### Indexes and Columns
+
+Specialized methods are available to get more detailed information:
+
+```swift
+let indexes = try schema.indexDefinitions("users")
+let columns = try schema.columnDefinitions("users")
+
+for index in indexes {
+    print("\(index.name) columns:\(index.columns))")
+}
+for column in columns {
+    print("\(column.name) pk:\(column.primaryKey) nullable: \(column.nullable)")
+}
+```
 
 ## Altering the Schema
 
@@ -1454,11 +1485,56 @@ tables](#creating-a-table).
 
 ### Renaming Columns
 
-Added in SQLite 3.25.0, not exposed yet. [#1073](https://github.com/stephencelis/SQLite.swift/issues/1073)
+We can rename columns with the help of the `SchemaChanger` class:
+
+```swift
+let schemaChanger = SchemaChanger(connection: db)
+try schemaChanger.alter(table: "users") { table in
+    table.rename(column: "old_name", to: "new_name")
+}
+```
 
 ### Dropping Columns
 
-Added in SQLite 3.35.0, not exposed yet. [#1073](https://github.com/stephencelis/SQLite.swift/issues/1073)
+```swift
+let schemaChanger = SchemaChanger(connection: db)
+try schemaChanger.alter(table: "users") { table in
+    table.drop(column: "email")
+}
+```
+
+These operations will work with all versions of SQLite and use modern SQL
+operations such as `DROP COLUMN` when available.
+
+### Adding Columns (SchemaChanger)
+
+The `SchemaChanger` provides an alternative API to add new columns:
+
+```swift
+let newColumn = ColumnDefinition(
+    name: "new_text_column",
+    type: .TEXT,
+    nullable: true,
+    defaultValue: .stringLiteral("foo")
+)
+
+let schemaChanger = SchemaChanger(connection: db)
+
+try schemaChanger.alter(table: "users") { table in
+    table.add(newColumn)
+}
+```
+
+### Renaming/dropping Tables (SchemaChanger)
+
+The `SchemaChanger` provides an alternative API to rename and drop tables:
+
+```swift
+let schemaChanger = SchemaChanger(connection: db)
+
+try schemaChanger.rename(table: "users", to: "users_new")
+try schemaChanger.drop(table: "emails")
+```
 
 ### Indexes
 
@@ -1515,7 +1591,6 @@ try db.run(users.dropIndex(email, ifExists: true))
 // DROP INDEX IF EXISTS "index_users_on_email"
 ```
 
-
 ### Dropping Tables
 
 We can build
@@ -1535,7 +1610,6 @@ try db.run(users.drop(ifExists: true))
 // DROP TABLE IF EXISTS "users"
 ```
 
-
 ### Migrations and Schema Versioning
 
 You can use the convenience property on `Connection` to query and set the

Makefile

@@ -18,6 +18,8 @@ build:
 
 lint:
 	swiftlint --strict
+lint-fix:
+	swiftlint lint fix
 
 test:
 ifdef XCPRETTY

SQLite.playground/Contents.swift

@@ -99,5 +99,33 @@ db.createAggregation("customConcat",
                      initialValue: "users:",
                      reduce: reduce,
                      result: { $0 })
-let result = db.prepare("SELECT customConcat(email) FROM users").scalar() as! String
+let result = try db.prepare("SELECT customConcat(email) FROM users").scalar() as! String
 print(result)
+
+/// schema queries
+let schema = db.schema
+let objects = try schema.objectDefinitions()
+print(objects)
+
+let columns = try schema.columnDefinitions(table: "users")
+print(columns)
+
+/// schema alteration
+
+let schemaChanger = SchemaChanger(connection: db)
+try schemaChanger.alter(table: "users") { table in
+    table.add(ColumnDefinition(name: "age", type: .INTEGER))
+    table.rename(column: "email", to: "electronic_mail")
+    table.drop(column: "name")
+}
+
+let changedColumns = try schema.columnDefinitions(table: "users")
+print(changedColumns)
+
+let age = Expression<Int?>("age")
+let electronicMail = Expression<String>("electronic_mail")
+
+let newRowid = try db.run(users.insert(
+    electronicMail <- "[email protected]",
+    age <- 33
+))

SQLite.xcodeproj/project.pbxproj

@@ -199,6 +199,18 @@
 		997DF2AF287FC06D00F8DF95 /* Query+with.swift in Sources */ = {isa = PBXBuildFile; fileRef = 997DF2AD287FC06D00F8DF95 /* Query+with.swift */; };
 		997DF2B0287FC06D00F8DF95 /* Query+with.swift in Sources */ = {isa = PBXBuildFile; fileRef = 997DF2AD287FC06D00F8DF95 /* Query+with.swift */; };
 		997DF2B1287FC06D00F8DF95 /* Query+with.swift in Sources */ = {isa = PBXBuildFile; fileRef = 997DF2AD287FC06D00F8DF95 /* Query+with.swift */; };
+		DB58B21128FB864300F8EEA4 /* SchemaReader.swift in Sources */ = {isa = PBXBuildFile; fileRef = DB58B21028FB864300F8EEA4 /* SchemaReader.swift */; };
+		DB58B21228FB864300F8EEA4 /* SchemaReader.swift in Sources */ = {isa = PBXBuildFile; fileRef = DB58B21028FB864300F8EEA4 /* SchemaReader.swift */; };
+		DB58B21328FB864300F8EEA4 /* SchemaReader.swift in Sources */ = {isa = PBXBuildFile; fileRef = DB58B21028FB864300F8EEA4 /* SchemaReader.swift */; };
+		DB58B21428FB864300F8EEA4 /* SchemaReader.swift in Sources */ = {isa = PBXBuildFile; fileRef = DB58B21028FB864300F8EEA4 /* SchemaReader.swift */; };
+		DB58B21628FC7C4600F8EEA4 /* SQLiteFeature.swift in Sources */ = {isa = PBXBuildFile; fileRef = DB58B21528FC7C4600F8EEA4 /* SQLiteFeature.swift */; };
+		DB58B21728FC7C4600F8EEA4 /* SQLiteFeature.swift in Sources */ = {isa = PBXBuildFile; fileRef = DB58B21528FC7C4600F8EEA4 /* SQLiteFeature.swift */; };
+		DB58B21828FC7C4600F8EEA4 /* SQLiteFeature.swift in Sources */ = {isa = PBXBuildFile; fileRef = DB58B21528FC7C4600F8EEA4 /* SQLiteFeature.swift */; };
+		DB58B21928FC7C4600F8EEA4 /* SQLiteFeature.swift in Sources */ = {isa = PBXBuildFile; fileRef = DB58B21528FC7C4600F8EEA4 /* SQLiteFeature.swift */; };
+		DB7C5DA628D7C9B6006395CF /* SQLiteVersion.swift in Sources */ = {isa = PBXBuildFile; fileRef = DB7C5DA528D7C9B6006395CF /* SQLiteVersion.swift */; };
+		DB7C5DA728D7C9B6006395CF /* SQLiteVersion.swift in Sources */ = {isa = PBXBuildFile; fileRef = DB7C5DA528D7C9B6006395CF /* SQLiteVersion.swift */; };
+		DB7C5DA828D7C9B6006395CF /* SQLiteVersion.swift in Sources */ = {isa = PBXBuildFile; fileRef = DB7C5DA528D7C9B6006395CF /* SQLiteVersion.swift */; };
+		DB7C5DA928D7C9B6006395CF /* SQLiteVersion.swift in Sources */ = {isa = PBXBuildFile; fileRef = DB7C5DA528D7C9B6006395CF /* SQLiteVersion.swift */; };
 		EE247AD71C3F04ED00AE3E12 /* SQLite.h in Headers */ = {isa = PBXBuildFile; fileRef = EE247AD61C3F04ED00AE3E12 /* SQLite.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		EE247ADE1C3F04ED00AE3E12 /* SQLite.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = EE247AD31C3F04ED00AE3E12 /* SQLite.framework */; };
 		EE247B031C3F06E900AE3E12 /* Blob.swift in Sources */ = {isa = PBXBuildFile; fileRef = EE247AEE1C3F06E900AE3E12 /* Blob.swift */; };
@@ -325,6 +337,9 @@
 		49EB68C31F7B3CB400D89D40 /* Coding.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Coding.swift; sourceTree = "<group>"; };
 		997DF2AD287FC06D00F8DF95 /* Query+with.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Query+with.swift"; sourceTree = "<group>"; };
 		A121AC451CA35C79005A31D1 /* SQLite.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = SQLite.framework; sourceTree = BUILT_PRODUCTS_DIR; };
+		DB58B21028FB864300F8EEA4 /* SchemaReader.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = SchemaReader.swift; sourceTree = "<group>"; };
+		DB58B21528FC7C4600F8EEA4 /* SQLiteFeature.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = SQLiteFeature.swift; sourceTree = "<group>"; };
+		DB7C5DA528D7C9B6006395CF /* SQLiteVersion.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = SQLiteVersion.swift; sourceTree = "<group>"; };
 		EE247AD31C3F04ED00AE3E12 /* SQLite.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = SQLite.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		EE247AD61C3F04ED00AE3E12 /* SQLite.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = SQLite.h; sourceTree = "<group>"; };
 		EE247AD81C3F04ED00AE3E12 /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
@@ -424,6 +439,7 @@
 		19A1792D261C689FC988A90A /* Schema */ = {
 			isa = PBXGroup;
 			children = (
+				DB58B21028FB864300F8EEA4 /* SchemaReader.swift */,
 				19A171B262DDE8718513CFDA /* SchemaChanger.swift */,
 				19A17268AE67B746B96AC125 /* SchemaDefinitions.swift */,
 				19A170A97B51DC5EE365F3C5 /* Connection+Schema.swift */,
@@ -569,6 +585,8 @@
 				19A175A9CB446640AE6F2200 /* Connection+Aggregation.swift */,
 				3DF7B78728842972005DD8CA /* Connection+Attach.swift */,
 				3DF7B790288449BA005DD8CA /* URIQueryParameter.swift */,
+				DB58B21528FC7C4600F8EEA4 /* SQLiteFeature.swift */,
+				DB7C5DA528D7C9B6006395CF /* SQLiteVersion.swift */,
 				19A17F285B767BFACD96714B /* Connection+Pragmas.swift */,
 			);
 			path = Core;
@@ -954,13 +972,16 @@
 				02A43A9A22738CF100FEC494 /* Backup.swift in Sources */,
 				19A17FF4A10B44D3937C8CAC /* Errors.swift in Sources */,
 				19A1737286A74F3CF7412906 /* DateAndTimeFunctions.swift in Sources */,
+				DB7C5DA828D7C9B6006395CF /* SQLiteVersion.swift in Sources */,
 				19A17073552293CA063BEA66 /* Result.swift in Sources */,
 				997DF2B0287FC06D00F8DF95 /* Query+with.swift in Sources */,
 				19A179B59450FE7C4811AB8A /* Connection+Aggregation.swift in Sources */,
+				DB58B21828FC7C4600F8EEA4 /* SQLiteFeature.swift in Sources */,
 				19A17FC07731779C1B8506FA /* SchemaChanger.swift in Sources */,
 				19A1740EACD47904AA24B8DC /* SchemaDefinitions.swift in Sources */,
 				19A1750EF4A5F92954A451FF /* Connection+Schema.swift in Sources */,
 				19A17986405D9A875698408F /* Connection+Pragmas.swift in Sources */,
+				DB58B21328FB864300F8EEA4 /* SchemaReader.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -1011,9 +1032,12 @@
 				997DF2B1287FC06D00F8DF95 /* Query+with.swift in Sources */,
 				3D67B3F71DB246D700A4F4C6 /* Foundation.swift in Sources */,
 				3D67B3F81DB246D700A4F4C6 /* Helpers.swift in Sources */,
+				DB58B21428FB864300F8EEA4 /* SchemaReader.swift in Sources */,
 				3D67B3E91DB246D100A4F4C6 /* Statement.swift in Sources */,
+				DB7C5DA928D7C9B6006395CF /* SQLiteVersion.swift in Sources */,
 				3D67B3EA1DB246D100A4F4C6 /* Value.swift in Sources */,
 				3D67B3EB1DB246D100A4F4C6 /* FTS4.swift in Sources */,
+				DB58B21928FC7C4600F8EEA4 /* SQLiteFeature.swift in Sources */,
 				3D67B3EC1DB246D100A4F4C6 /* RTree.swift in Sources */,
 				3D67B3ED1DB246D100A4F4C6 /* FTS5.swift in Sources */,
 				3D67B3EE1DB246D100A4F4C6 /* AggregateFunctions.swift in Sources */,
@@ -1069,13 +1093,16 @@
 				02A43A9822738CF100FEC494 /* Backup.swift in Sources */,
 				19A1792C0520D4E83C2EB075 /* Errors.swift in Sources */,
 				19A17E29278A12BC4F542506 /* DateAndTimeFunctions.swift in Sources */,
+				DB7C5DA628D7C9B6006395CF /* SQLiteVersion.swift in Sources */,
 				19A173EFEF0B3BD0B3ED406C /* Result.swift in Sources */,
 				997DF2AE287FC06D00F8DF95 /* Query+with.swift in Sources */,
 				19A176376CB6A94759F7980A /* Connection+Aggregation.swift in Sources */,
+				DB58B21628FC7C4600F8EEA4 /* SQLiteFeature.swift in Sources */,
 				19A1773A335CAB9D0AE14E8E /* SchemaChanger.swift in Sources */,
 				19A17BA13FD35F058787B7D3 /* SchemaDefinitions.swift in Sources */,
 				19A174506543905D71BF0518 /* Connection+Schema.swift in Sources */,
 				19A17018F250343BD0F9F4B0 /* Connection+Pragmas.swift in Sources */,
+				DB58B21128FB864300F8EEA4 /* SchemaReader.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -1146,13 +1173,16 @@
 				02A43A9922738CF100FEC494 /* Backup.swift in Sources */,
 				19A17490543609FCED53CACC /* Errors.swift in Sources */,
 				19A17152E32A9585831E3FE0 /* DateAndTimeFunctions.swift in Sources */,
+				DB7C5DA728D7C9B6006395CF /* SQLiteVersion.swift in Sources */,
 				19A17F1B3F0A3C96B5ED6D64 /* Result.swift in Sources */,
 				997DF2AF287FC06D00F8DF95 /* Query+with.swift in Sources */,
 				19A170ACC97B19730FB7BA4D /* Connection+Aggregation.swift in Sources */,
+				DB58B21728FC7C4600F8EEA4 /* SQLiteFeature.swift in Sources */,
 				19A177290558991BCC60E4E3 /* SchemaChanger.swift in Sources */,
 				19A17B0DF1DDB6BBC9C95D64 /* SchemaDefinitions.swift in Sources */,
 				19A17F0BF02896E1664F4090 /* Connection+Schema.swift in Sources */,
 				19A1760CE25615CA015E2E5F /* Connection+Pragmas.swift in Sources */,
+				DB58B21228FB864300F8EEA4 /* SchemaReader.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

Sources/SQLite/Core/Connection+Pragmas.swift

@@ -1,7 +1,6 @@
 import Foundation
 
 public typealias UserVersion = Int32
-public typealias SQLiteVersion = (Int, Int, Int)
 
 public extension Connection {
     /// The user version of the database.
@@ -21,9 +20,9 @@ public extension Connection {
         guard let version = (try? scalar("SELECT sqlite_version()")) as? String,
               let splits = .some(version.split(separator: ".", maxSplits: 3)), splits.count == 3,
               let major = Int(splits[0]), let minor = Int(splits[1]), let point = Int(splits[2]) else {
-            return (0, 0, 0)
+            return .zero
         }
-        return (major, minor, point)
+        return .init(major: major, minor: minor, point: point)
     }
 
     // Changing the foreign_keys setting affects the execution of all statements prepared using the database

Sources/SQLite/Core/SQLiteFeature.swift

@@ -0,0 +1,25 @@
+import Foundation
+
+enum SQLiteFeature {
+    case partialIntegrityCheck      // PRAGMA integrity_check(table)
+    case sqliteSchemaTable          // sqlite_master => sqlite_schema
+    case renameColumn               // ALTER TABLE ... RENAME COLUMN
+    case dropColumn                 // ALTER TABLE ... DROP COLUMN
+
+    func isSupported(by version: SQLiteVersion) -> Bool {
+        switch self {
+        case .partialIntegrityCheck, .sqliteSchemaTable:
+            return version >= .init(major: 3, minor: 33)
+        case .renameColumn:
+            return version >= .init(major: 3, minor: 25)
+        case .dropColumn:
+            return version >= .init(major: 3, minor: 35)
+        }
+    }
+}
+
+extension Connection {
+    func supports(_ feature: SQLiteFeature) -> Bool {
+        feature.isSupported(by: sqliteVersion)
+    }
+}

Sources/SQLite/Core/SQLiteVersion.swift

@@ -0,0 +1,22 @@
+import Foundation
+
+public struct SQLiteVersion: Comparable, CustomStringConvertible {
+    public let major: Int
+    public let minor: Int
+    public var point: Int = 0
+
+    public var description: String {
+        "SQLite \(major).\(minor).\(point)"
+    }
+
+    public static func <(lhs: SQLiteVersion, rhs: SQLiteVersion) -> Bool {
+        lhs.tuple < rhs.tuple
+    }
+
+    public static func ==(lhs: SQLiteVersion, rhs: SQLiteVersion) -> Bool {
+        lhs.tuple == rhs.tuple
+    }
+
+    static var zero: SQLiteVersion = .init(major: 0, minor: 0)
+    private var tuple: (Int, Int, Int) { (major, minor, point) }
+}