Merge pull request #571 from rausnitz/safe-sum

Safe sum
vapor · Oct 17, 2018 · 25eeedf · 25eeedf
2 parents 291aaec + 7f98167
commit 25eeedf
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Showing 2 changed files with 42 additions and 4 deletions.
diff --git a/Sources/Fluent/QueryBuilder/QueryBuilder+Aggregate.swift b/Sources/Fluent/QueryBuilder/QueryBuilder+Aggregate.swift
@@ -1,15 +1,22 @@
 extension QueryBuilder {
     // MARK: Aggregate
 
-    /// Returns the sum of all entries for the supplied field.
+    /// Returns the sum of all entries for the supplied field, falling back to the default value if the Future containing the sum resolves to an Error.
     ///
     ///     let totalLikes = try Post.query(on: conn).sum(\.likes)
+    ///     let totalViralPostLikes = try Post.query(on: conn).filter(\.likes >= 10_000_000).sum(\.likes, default: 0)
     ///
     /// - parameters:
     ///     - field: Field to sum.
+    ///     - default: Optional default to use.
     /// - returns: A `Future` containing the sum.
-    public func sum<T>(_ field: KeyPath<Result, T>) -> Future<T> where T: Decodable {
-        return aggregate(Database.queryAggregateSum, field: field)
+    public func sum<T>(_ field: KeyPath<Result, T>, default: T? = nil) -> Future<T> where T: Decodable {
+        return aggregate(Database.queryAggregateSum, field: field).catchMap { error in
+            guard let d = `default` else {
+                throw error
+            }
+            return d
+        }
     }
 
     /// Returns the average of all entries for the supplied field.

diff --git a/Sources/FluentBenchmark/Benchmarks/BenchmarkAggregate.swift b/Sources/FluentBenchmark/Benchmarks/BenchmarkAggregate.swift
@@ -14,6 +14,33 @@ extension Benchmarker where Database: QuerySupporting {
         if all.count != count {
             fail("wrong count: \(all.count) != \(count)")
         }
+
+        let firstSummer = User<Database>(name: "Summer", age: 30)
+        let secondSummer = User<Database>(name: "Summer", age: 31)
+        _ = try test(firstSummer.create(on: conn))
+        _ = try test(secondSummer.create(on: conn))
+        let summersSum = try User<Database>.query(on: conn).filter(\.name == "Summer").sum(\.age).wait()
+        if summersSum != 61 {
+            fail("sum should be 61")
+        }
+
+        let autumn = User<Database>(name: "Autumn", age: 40)
+        do {
+            _ = try User<Database>.query(on: conn).filter(\.name == "Autumn").sum(\.age).wait()
+            fail("should not have produced a sum")
+        } catch {
+            let defaultSum = try User<Database>.query(on: conn).filter(\.name == "Autumn").sum(\.age, default: 0).wait()
+            if defaultSum != 0 {
+                fail("should have defaulted to 0")
+            }
+        }
+
+        _ = try test(autumn.create(on: conn))
+        let autumnsSum = try User<Database>.query(on: conn).filter(\.name == "Autumn").sum(\.age).wait()
+        let alsoAutumnsSum = try User<Database>.query(on: conn).filter(\.name == "Autumn").sum(\.age, default: 0).wait()
+        if autumnsSum != 40 || alsoAutumnsSum != 40 {
+            fail("sum should be 40, whether or not a default is provided")
+        }
     }
 
     public func benchmarkAggregate() throws {
@@ -26,8 +53,12 @@ extension Benchmarker where Database: QuerySupporting {
 extension Benchmarker where Database: QuerySupporting & SchemaSupporting & MigrationSupporting {
     public func benchmarkAggregate_withSchema() throws {
         let conn = try test(pool.requestConnection())
-        defer { try? test(Galaxy<Database>.revert(on: conn)) }
+        defer {
+            try? test(Galaxy<Database>.revert(on: conn))
+            try? test(UserMigration<Database>.revert(on: conn))
+        }
         try test(Galaxy<Database>.prepare(on: conn))
+        try test(UserMigration<Database>.prepare(on: conn))
         try self._benchmark(on: conn)
         pool.releaseConnection(conn)
     }