Repository: stephencelis/SQLite.swift (swift)

Issue:
insertMany() fails when encodables have nil on different fields between them.
`insertMany(_ encodables: [Encodable])` fails when optional fields (nullable) have `nil` as its value on different fields among them.

Getting this message/error:
```
2022-04-28 09:23:36.842911-0400 SQliteBug[28203:735825] [logging] all VALUES must have the same number of terms in "INSERT INTO "person" ("name", "email") VALUES (?, ?), (?)"
Error The operation couldn’t be completed. (SQLite.Result error 0.)
```

## Build Information

- SQLite.swift v.0.13.3, revision: 4d543d811ee644fa4cc4bfa0be996b4dd6ba0f54
- Xcode 13.3.1. macOS Big Sur 11.6.5 / macOS Monterey 12.3.1
- How do do you integrate SQLite.swift in your project?
    - Swift Package manager

## General guidelines

- To reproduce the issue you can check this repo I created exclusively for this issue: https://github.com/duhnnie/SQLite.swift-Issue
- Or you can paste this code on your Swift project with SQLite.swift:
```swift
import SQLite
import Foundation

struct Person: Codable {
    let id: Int?
    let name: String
    let email: String?
    
    init(id: Int? = nil, name: String, email: String? = nil) {
        self.id = id
        self.name = name
        self.email = email
    }
}

let db = try Connection(NSHomeDirectory() + "/dbtest.sqlite")

let person = Table("person")
let id = Expression<Int64>("id")
let name = Expression<String>("name")
let email = Expression<String?>("email")

let createTable = person.create(ifNotExists: true) { t in
    t.column(id, primaryKey: true)
    t.column(name)
    t.column(email)
}

try db.run(createTable)

let person1 = Person(name: "John", email: "john@doe.com")
let person2 = Person(name: "David", email: nil)
let personsArray = [person1, person2]

do {
    let insert = try person.insertMany(personsArray)
    try db.run(insert)
} catch {
    print("Error \(error.localizedDescription)")
}
```

Thanks in advance.

Pull request description:
Fixes #1130, original PR (by me) was #1048

The problem was if you are trying to INSERT many rows, and some of those rows have different quantity of setters due to optional values, the INSERT query will fail with `all VALUES must have the same number of terms in "INSERT INTO...`

We needed to either guarantee that each `Encodable` will have the same number of setters OR force equivalent numbers of setters by adding NULL where the optional value is nil. This can be done with the `encodeIfPresent` methods on `KeyedEncodingContainerProtocol` in `SQLiteKeyedEncodingContainer`

Patch:
diff --git a/Sources/SQLite/Typed/Coding.swift b/Sources/SQLite/Typed/Coding.swift
index ec2e0d6c..b96bc64e 100644
--- a/Sources/SQLite/Typed/Coding.swift
+++ b/Sources/SQLite/Typed/Coding.swift
@@ -86,12 +86,22 @@ extension QueryType {
     /// - Returns: An `INSERT` statement for the encodable objects
     public func insertMany(_ encodables: [Encodable], userInfo: [CodingUserInfoKey: Any] = [:],
                            otherSetters: [Setter] = []) throws -> Insert {
-        let combinedSetters = try encodables.map { encodable -> [Setter] in
-            let encoder = SQLiteEncoder(userInfo: userInfo)
+        let combinedSettersWithoutNils = try encodables.map { encodable -> [Setter] in
+            let encoder = SQLiteEncoder(userInfo: userInfo, forcingNilValueSetters: false)
             try encodable.encode(to: encoder)
             return encoder.setters + otherSetters
         }
-        return self.insertMany(combinedSetters)
+        // requires the same number of setters per encodable
+        guard Set(combinedSettersWithoutNils.map(\.count)).count == 1 else {
+            // asymmetric sets of value insertions (some nil, some not), requires NULL value to satisfy INSERT query
+            let combinedSymmetricSetters = try encodables.map { encodable -> [Setter] in
+                let encoder = SQLiteEncoder(userInfo: userInfo, forcingNilValueSetters: true)
+                try encodable.encode(to: encoder)
+                return encoder.setters + otherSetters
+            }
+            return self.insertMany(combinedSymmetricSetters)
+        }
+        return self.insertMany(combinedSettersWithoutNils)
     }
 
     /// Creates an `INSERT ON CONFLICT DO UPDATE` statement, aka upsert, by encoding the given object
@@ -165,9 +175,11 @@ private class SQLiteEncoder: Encoder {
 
         let encoder: SQLiteEncoder
         let codingPath: [CodingKey] = []
+        let forcingNilValueSetters: Bool
 
-        init(encoder: SQLiteEncoder) {
+        init(encoder: SQLiteEncoder, forcingNilValueSetters: Bool = false) {
             self.encoder = encoder
+            self.forcingNilValueSetters = forcingNilValueSetters
         }
 
         func superEncoder() -> Swift.Encoder {
@@ -202,6 +214,46 @@ private class SQLiteEncoder: Encoder {
             encoder.setters.append(Expression(key.stringValue) <- value)
         }
 
+        func encodeIfPresent(_ value: Int?, forKey key: SQLiteEncoder.SQLiteKeyedEncodingContainer<Key>.Key) throws {
+            if let value = value {
+                try encode(value, forKey: key)
+            } else if forcingNilValueSetters {
+                encoder.setters.append(Expression<Int?>(key.stringValue) <- nil)
+            }
+        }
+
+        func encodeIfPresent(_ value: Bool?, forKey key: Key) throws {
+            if let value = value {
+                try encode(value, forKey: key)
+            } else if forcingNilValueSetters {
+                encoder.setters.append(Expression<Bool?>(key.stringValue) <- nil)
+            }
+        }
+
+        func encodeIfPresent(_ value: Float?, forKey key: Key) throws {
+            if let value = value {
+                try encode(value, forKey: key)
+            } else if forcingNilValueSetters {
+                encoder.setters.append(Expression<Double?>(key.stringValue) <- nil)
+            }
+        }
+
+        func encodeIfPresent(_ value: Double?, forKey key: Key) throws {
+            if let value = value {
+                try encode(value, forKey: key)
+            } else if forcingNilValueSetters {
+                encoder.setters.append(Expression<Double?>(key.stringValue) <- nil)
+            }
+        }
+
+        func encodeIfPresent(_ value: String?, forKey key: MyKey) throws {
+            if let value = value {
+                try encode(value, forKey: key)
+            } else if forcingNilValueSetters {
+                encoder.setters.append(Expression<String?>(key.stringValue) <- nil)
+            }
+        }
+
         func encode<T>(_ value: T, forKey key: Key) throws where T: Swift.Encodable {
             switch value {
             case let data as Data:
@@ -217,6 +269,17 @@ private class SQLiteEncoder: Encoder {
             }
         }
 
+        func encodeIfPresent<T>(_ value: T?, forKey key: Key) throws where T: Swift.Encodable {
+            guard let value = value else {
+                guard forcingNilValueSetters else {
+                    return
+                }
+                encoder.setters.append(Expression<String?>(key.stringValue) <- nil)
+                return
+            }
+            try encode(value, forKey: key)
+        }
+
         func encode(_ value: Int8, forKey key: Key) throws {
             throw EncodingError.invalidValue(value, EncodingError.Context(codingPath: codingPath,
                                                                           debugDescription: "encoding an Int8 is not supported"))
@@ -274,9 +337,11 @@ private class SQLiteEncoder: Encoder {
     fileprivate var setters: [Setter] = []
     let codingPath: [CodingKey] = []
     let userInfo: [CodingUserInfoKey: Any]
+    let forcingNilValueSetters: Bool
 
-    init(userInfo: [CodingUserInfoKey: Any]) {
+    init(userInfo: [CodingUserInfoKey: Any], forcingNilValueSetters: Bool = false) {
         self.userInfo = userInfo
+        self.forcingNilValueSetters = forcingNilValueSetters
     }
 
     func singleValueContainer() -> SingleValueEncodingContainer {
@@ -288,7 +353,7 @@ private class SQLiteEncoder: Encoder {
     }
 
     func container<Key>(keyedBy type: Key.Type) -> KeyedEncodingContainer<Key> where Key: CodingKey {
-        KeyedEncodingContainer(SQLiteKeyedEncodingContainer(encoder: self))
+        KeyedEncodingContainer(SQLiteKeyedEncodingContainer(encoder: self, forcingNilValueSetters: forcingNilValueSetters))
     }
 }
 


Test patch:
diff --git a/Tests/SQLiteTests/QueryIntegrationTests.swift b/Tests/SQLiteTests/QueryIntegrationTests.swift
index b3d9cf96..f3b4bcd3 100644
--- a/Tests/SQLiteTests/QueryIntegrationTests.swift
+++ b/Tests/SQLiteTests/QueryIntegrationTests.swift
@@ -130,6 +130,28 @@ class QueryIntegrationTests: SQLiteTestCase {
         XCTAssertEqual(2, id)
     }
 
+    func test_insert_many_encodables() throws {
+        let table = Table("codable")
+        try db.run(table.create { builder in
+            builder.column(Expression<Int?>("int"))
+            builder.column(Expression<String?>("string"))
+            builder.column(Expression<Bool?>("bool"))
+            builder.column(Expression<Double?>("float"))
+            builder.column(Expression<Double?>("double"))
+            builder.column(Expression<Date?>("date"))
+            builder.column(Expression<UUID?>("uuid"))
+        })
+
+        let value1 = TestOptionalCodable(int: 5, string: "6", bool: true, float: 7, double: 8,
+                                         date: Date(timeIntervalSince1970: 5000), uuid: testUUIDValue)
+        let valueWithNils = TestOptionalCodable(int: nil, string: nil, bool: nil, float: nil, double: nil, date: nil, uuid: nil)
+        try db.run(table.insertMany([value1, valueWithNils]))
+
+         let rows = try db.prepare(table)
+         let values: [TestOptionalCodable] = try rows.map({ try $0.decode() })
+         XCTAssertEqual(values.count, 2)
+    }
+
     func test_upsert() throws {
         try XCTSkipUnless(db.satisfiesMinimumVersion(minor: 24))
         let fetchAge = { () throws -> Int? in
diff --git a/Tests/SQLiteTests/QueryTests.swift b/Tests/SQLiteTests/QueryTests.swift
index 2201caef..b2f679e0 100644
--- a/Tests/SQLiteTests/QueryTests.swift
+++ b/Tests/SQLiteTests/QueryTests.swift
@@ -365,21 +365,21 @@ class QueryTests: XCTestCase {
         )
     }
 
-    func test_insert_many_encodable() throws {
+    func test_insert_many_encodables() throws {
         let emails = Table("emails")
         let value1 = TestCodable(int: 1, string: "2", bool: true, float: 3, double: 4,
                                  date: Date(timeIntervalSince1970: 0), uuid: testUUIDValue, optional: nil, sub: nil)
         let value2 = TestCodable(int: 2, string: "3", bool: true, float: 3, double: 5,
-                                 date: Date(timeIntervalSince1970: 0), uuid: testUUIDValue, optional: nil, sub: nil)
+                                 date: Date(timeIntervalSince1970: 0), uuid: testUUIDValue, optional: "optional", sub: nil)
         let value3 = TestCodable(int: 3, string: "4", bool: true, float: 3, double: 6,
                                  date: Date(timeIntervalSince1970: 0), uuid: testUUIDValue, optional: nil, sub: nil)
         let insert = try emails.insertMany([value1, value2, value3])
         assertSQL(
             """
-            INSERT INTO \"emails\" (\"int\", \"string\", \"bool\", \"float\", \"double\", \"date\", \"uuid\")
-             VALUES (1, '2', 1, 3.0, 4.0, '1970-01-01T00:00:00.000', 'E621E1F8-C36C-495A-93FC-0C247A3E6E5F'),
-             (2, '3', 1, 3.0, 5.0, '1970-01-01T00:00:00.000', 'E621E1F8-C36C-495A-93FC-0C247A3E6E5F'),
-             (3, '4', 1, 3.0, 6.0, '1970-01-01T00:00:00.000', 'E621E1F8-C36C-495A-93FC-0C247A3E6E5F')
+            INSERT INTO \"emails\" (\"int\", \"string\", \"bool\", \"float\", \"double\", \"date\", \"uuid\", \"optional\", \"sub\")
+             VALUES (1, '2', 1, 3.0, 4.0, '1970-01-01T00:00:00.000', 'E621E1F8-C36C-495A-93FC-0C247A3E6E5F', NULL, NULL),
+             (2, '3', 1, 3.0, 5.0, '1970-01-01T00:00:00.000', 'E621E1F8-C36C-495A-93FC-0C247A3E6E5F', 'optional', NULL),
+             (3, '4', 1, 3.0, 6.0, '1970-01-01T00:00:00.000', 'E621E1F8-C36C-495A-93FC-0C247A3E6E5F', NULL, NULL)
             """.replacingOccurrences(of: "\n", with: ""),
             insert
         )
diff --git a/Tests/SQLiteTests/TestHelpers.swift b/Tests/SQLiteTests/TestHelpers.swift
index 4a71fd40..f43310c9 100644
--- a/Tests/SQLiteTests/TestHelpers.swift
+++ b/Tests/SQLiteTests/TestHelpers.swift
@@ -145,3 +145,23 @@ class TestCodable: Codable, Equatable {
         lhs.sub == rhs.sub
     }
 }
+
+struct TestOptionalCodable: Codable, Equatable {
+    let int: Int?
+    let string: String?
+    let bool: Bool?
+    let float: Float?
+    let double: Double?
+    let date: Date?
+    let uuid: UUID?
+
+    init(int: Int?, string: String?, bool: Bool?, float: Float?, double: Double?, date: Date?, uuid: UUID?) {
+        self.int = int
+        self.string = string
+        self.bool = bool
+        self.float = float
+        self.double = double
+        self.date = date
+        self.uuid = uuid
+    }
+}