Clarify ALTER TABLE restrictions (#66)

* clarify sqlite ALTER TABLE restrictions

* cleanup tests

* bump

Author: tanner0101

.github/workflows/api-docs.yml

@@ -3,7 +3,6 @@ on:
    push:
      branches:
        - master
-
 jobs:
   deploy:
     name: api.vapor.codes

.github/workflows/test.yml

@@ -1,18 +1,14 @@
-name: Test Matrix
-
+name: test
 on:
   pull_request:
   push:
     branches:
     - master
-
 defaults:
   run:
     shell: bash
-
 jobs:
-
-  Linux:
+  linux:
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
@@ -34,11 +30,11 @@ jobs:
           - swiftlang/swift:nightly-master-centos8
           - swiftlang/swift:nightly-master-amazonlinux2
         include:
-          - depscmd: 'apt-get -q update && apt-get -q install -y libsqlite3-dev'
+          - depscmd: apt-get -q update && apt-get -q install -y libsqlite3-dev
           - image: swiftlang/swift:nightly-master-centos8
-            depscmd: 'dnf install -y sqlite-devel'
+            depscmd: dnf install -y sqlite-devel
           - image: swiftlang/swift:nightly-master-amazonlinux2
-            depscmd: 'yum install -y sqlite-devel'
+            depscmd: yum install -y sqlite-devel
     container: ${{ matrix.image }}
     steps:
       - name: Install dependencies
@@ -57,14 +53,15 @@ jobs:
         uses: actions/checkout@v2
       - name: Run tests with Thread Sanitizer
         run: swift test --enable-test-discovery --sanitize=thread
-
   macOS:
     runs-on: macos-latest
     steps:
       - name: Select latest available Xcode
         uses: maxim-lobanov/setup-xcode@1.0
-        with: { 'xcode-version': 'latest' }
+        with:
+          xcode-version: latest
       - name: Checkout code
         uses: actions/checkout@v2
       - name: Run tests with Thread Sanitizer
         run: swift test --enable-test-discovery --sanitize=thread
+

.gitignore

@@ -8,4 +8,4 @@ database.db
 Package.resolved
 DerivedData
 .swiftpm
-
+Tests/LinuxMain.swift

Sources/FluentSQLiteDriver/FluentSQLiteDatabase.swift

@@ -68,10 +68,34 @@ extension _FluentSQLiteDatabase: Database {
     }
 
     func execute(schema: DatabaseSchema) -> EventLoopFuture<Void> {
+        var schema = schema
         switch schema.action {
         case .update:
+            // Remove enum updates as they are unnecessary.
+            schema.updateFields = schema.updateFields.filter({
+                switch $0 {
+                case .custom:
+                    return true
+                case .dataType(_, let dataType):
+                    switch dataType {
+                    case .enum:
+                        return false
+                    default:
+                        return true
+                    }
+                }
+            })
+            guard 
+                schema.createConstraints.isEmpty,
+                schema.updateFields.isEmpty, 
+                schema.deleteFields.isEmpty,
+                schema.deleteConstraints.isEmpty
+            else {
+                return self.eventLoop.makeFailedFuture(FluentSQLiteError.unsupportedAlter)
+            }
+
+            // If only enum updates, then skip.
             if schema.createFields.isEmpty {
-                self.logger.warning("Ignoring schema update. SQLite only supports adding columns to existing tables")
                 return self.eventLoop.makeSucceededFuture(())
             }
         default:
@@ -103,6 +127,17 @@ extension _FluentSQLiteDatabase: Database {
     }
 }
 
+private enum FluentSQLiteError: Error, CustomStringConvertible {
+    case unsupportedAlter
+
+    var description: String {
+        switch self {
+        case .unsupportedAlter:
+            return "SQLite only supports adding columns in ALTER TABLE statements."
+        }
+    }
+}
+
 extension _FluentSQLiteDatabase: SQLDatabase {
     var dialect: SQLDialect {
         SQLiteDialect()

Tests/FluentSQLiteDriverTests/FluentSQLiteDriverTests.swift

@@ -66,6 +66,47 @@ final class FluentSQLiteDriverTests: XCTestCase {
             XCTFail("\(error)")
         }
     }
+
+    // https://github.com/vapor/fluent-sqlite-driver/issues/62
+    func testUnsupportedUpdateMigration() throws {
+        struct UserMigration_v1_0_0: Migration {
+            func prepare(on database: Database) -> EventLoopFuture<Void> {
+                database.schema("users")
+                    .id()
+                    .field("email", .string, .required)
+                    .field("password", .string, .required)
+                    .unique(on: "email")
+                    .create()
+            }
+
+            func revert(on database: Database) -> EventLoopFuture<Void> {
+                database.schema("users").delete()
+            }
+        }
+        struct UserMigration_v1_2_0: Migration {
+            func prepare(on database: Database) -> EventLoopFuture<Void> {
+                database.schema("users")
+                    .field("apple_id", .string)
+                    .unique(on: "apple_id")
+                    .update()
+            }
+
+            func revert(on database: Database) -> EventLoopFuture<Void> {
+                database.schema("users")
+                    .deleteField("apple_id")
+                    .update()
+            }
+        }
+        try UserMigration_v1_0_0().prepare(on: self.database).wait()
+        do {
+            try UserMigration_v1_2_0().prepare(on: self.database).wait()
+            try UserMigration_v1_2_0().revert(on: self.database).wait()
+        } catch {
+            print(error)
+            XCTAssertTrue("\(error)".contains("adding columns"))
+        }
+        try UserMigration_v1_0_0().revert(on: self.database).wait()
+    }
 
     var benchmarker: FluentBenchmarker {
         return .init(databases: self.dbs)