Async individuals support #845

Author: Thorium

src/SQLProvider.Common/SqlRuntime.Common.fs

@@ -548,6 +548,8 @@ and ISqlDataContext =
     abstract CallSprocAsync             : RunTimeSprocDefinition * QueryParameter[] * obj[] -> System.Threading.Tasks.Task<SqlEntity>
     /// Get individual row. Takes tablename and id.
     abstract GetIndividual              : string * obj -> SqlEntity
+    /// Get individual row asynchronously. Takes tablename and id.
+    abstract GetIndividualAsync         : string * obj -> System.Threading.Tasks.Task<SqlEntity>
     /// Save entity to database.
     abstract SubmitChangedEntity        : SqlEntity -> unit
     /// Save database-changes in a transaction to database.
@@ -1229,6 +1231,7 @@ module public OfflineTools =
                                 | false, _ ->
                                     failwith ("Add table to dummydata: " + pe)
                     member this.GetIndividual(arg1: string, arg2: obj): SqlEntity = raise (System.NotImplementedException())
+                    member this.GetIndividualAsync(arg1: string, arg2: obj): System.Threading.Tasks.Task<SqlEntity> = raise (System.NotImplementedException())
                     member this.GetPendingEntities(): SqlEntity list = (CommonTasks.sortEntities pendingChanges) |> Seq.toList
                     member this.GetPrimaryKeyDefinition(arg1: string): string = ""
                     member this.ReadEntities(arg1: string, arg2: FSharp.Data.Sql.Schema.ColumnLookup, arg3: Data.IDataReader): SqlEntity array = raise (System.NotImplementedException())

src/SQLProvider.DesignTime/SqlDesignTime.fs

@@ -240,7 +240,25 @@ module DesignTimeUtils =
                                                     , getterCode = getterCode
                                                     )
                             )
-                        |> Array.append( propertyMap |> Map.toArray |> Array.map (snd >> snd))
+                    
+                    // Add async method to fetch individual by primary key
+                    let tableName = table.FullName
+                    let pkColumn = columns.[pkName]
+                    let pkType = Utilities.getType pkColumn.TypeMapping.ClrType
+                    let returnType = typedefof<System.Threading.Tasks.Task<_>>.MakeGenericType(tableTypeDef)
+                    let getAsyncMethod =
+                        ProvidedMethod("GetAsync", [ProvidedParameter("id", pkType)], returnType, invokeCode = fun args ->
+                            let a0 = args.[0]
+                            let pkValue = args.[1]
+                            <@@ ((%%a0 : obj) :?> ISqlDataContext).GetIndividualAsync(tableName, %%pkValue) @@>
+                        )
+                    getAsyncMethod.AddXmlDoc(sprintf "<summary>Asynchronously get an individual %s by primary key value</summary>" table.Name)
+                    
+                    seq {
+                        yield getAsyncMethod :> MemberInfo
+                        yield! props |> Seq.cast<MemberInfo>
+                        yield! propertyMap |> Map.toSeq |> Seq.map (snd >> snd) |> Seq.cast<MemberInfo>
+                    } |> Seq.toList
 
                     propertyMap
                     |> Map.toSeq

src/SQLProvider.Runtime/SqlRuntime.DataContext.fs

@@ -236,6 +236,37 @@ type public SqlDataContext (typeName, connectionString:string, providerType:Data
             if provider.CloseConnectionAfterQuery then con.Close()
             entity
 
+        member this.GetIndividualAsync(table,id) =
+            task {
+                use con = provider.CreateConnection(connectionString) :?> System.Data.Common.DbConnection
+                let table = Table.FromFullName table
+                // this line is to ensure the columns for the table have been retrieved and therefore
+                // its primary key exists in the lookup
+                let columns = provider.GetColumns(con, table)
+                let pk =
+                    match provider.GetPrimaryKey table with
+                    | Some v -> columns.[v]
+                    | None ->
+                        // this fail case should not really be possible unless the runtime database is different to the design-time one
+                        failwithf "Primary key could not be found on object %s. Individuals only supported on objects with a single primary key." table.FullName
+                use com = provider.CreateCommand(con,provider.GetIndividualQueryText(table,pk.Name)) :?> System.Data.Common.DbCommand
+                if commandTimeout.IsSome then
+                    com.CommandTimeout <- commandTimeout.Value
+                //todo: establish pk SQL data type
+                com.Parameters.Add (provider.CreateCommandParameter(QueryParameter.Create("@id", 0, pk.TypeMapping),id)) |> ignore
+                if con.State <> ConnectionState.Open then 
+                    do! con.OpenAsync()
+                if con.State <> ConnectionState.Open then // Just ensure, as not all the providers seems to work so great with OpenAsync.
+                    if con.State <> ConnectionState.Closed && provider.CloseConnectionAfterQuery then con.Close()
+                    con.Open()
+                use! reader = com.ExecuteReaderAsync()
+                let! entities = (this :> ISqlDataContext).ReadEntitiesAsync(table.FullName, columns, reader)
+                let entity = entities |> Seq.exactlyOne
+                reader.Close()
+                if provider.CloseConnectionAfterQuery then con.Close()
+                return entity
+            }
+
         member this.ReadEntities(name: string, columns: ColumnLookup, reader: IDataReader) =
             [| while reader.Read() do
                  let e = SqlEntity(this, name, columns, reader.FieldCount)