Add support for restoring deleted entities

Sources/Sugar/Entity+Sugar.swift

@@ -51,3 +51,57 @@ extension Entity {
         try save()
     }
 }
+
+extension Entity where Self: SoftDeletable {
+    /// Saves or modifies (if already exists) a model given a value and field.
+    ///
+    /// - Parameters:
+    ///    - value: The value to look for.
+    ///    - field: The field to look in.
+    public func saveOrModify(
+        given value: NodeRepresentable,
+        for field: String,
+        beforeSave: ((Self, Self) -> ())? = nil,
+        withSoftDeleted: Bool = false,
+        restore: Bool = false
+    ) throws {
+        return try saveOrModify(
+            given: [field: value],
+            beforeSave: beforeSave,
+            withSoftDeleted: withSoftDeleted,
+            restore: restore
+        )
+    }
+    /// Saves of modifies (if already exists) a model given multiple values and fields.
+    ///
+    /// - Parameter values: The list of values and fields to look for.
+    /// - Throws: On db errors.
+    public func saveOrModify(
+        given values: [String: NodeRepresentable],
+        beforeSave: ((Self, Self) -> ())? = nil,
+        withSoftDeleted: Bool = false,
+        restore: Bool = false
+    ) throws {
+        var query = try Self.makeQuery()
+
+        if withSoftDeleted {
+            query = try query.withSoftDeleted()
+        }
+
+        for (field, value) in values {
+            query = try query.filter(field, value)
+        }
+        if let instance = try query.first() {
+            id = instance.id
+            exists = true
+            if let beforeSave = beforeSave {
+                beforeSave(instance, self)
+            }
+        }
+        try save()
+
+        if restore {
+            try self.restore()
+        }
+    }
+}