V6 NpgsqlModificationCommandBatch.ConsumeAsync commandIndex Out of Range

[trionia]

Applies only for version 6
I've stumbled across it a while ago, when my entity didn't match my table schema, but the exception was somehow cryptic.

After a bit of research I've found the following:

efcore.pg/src/EFCore.PG/Update/Internal/NpgsqlModificationCommandBatch.cs

Line 200 in f8a72da

var modificationCommand = ModificationCommands[commandIndex++];

If anything throws after that, like ReadAsync, and the current command is the last, the catch (Exception ex) block will throw IndexOutOfRangeException instead.

efcore.pg/src/EFCore.PG/Update/Internal/NpgsqlModificationCommandBatch.cs

Lines 220 to 226 in f8a72da

	catch (Exception ex)
	{
	throw new DbUpdateException(
	RelationalStrings.UpdateStoreException,
	ex,
	ModificationCommands[commandIndex].Entries);
	}

The solution could look like this:

diff --git a/src/EFCore.PG/Update/Internal/NpgsqlModificationCommandBatch.cs b/src/EFCore.PG/Update/Internal/NpgsqlModificationCommandBatch.cs
index 2d6ec3bb..ef00c788 100644
--- a/src/EFCore.PG/Update/Internal/NpgsqlModificationCommandBatch.cs
+++ b/src/EFCore.PG/Update/Internal/NpgsqlModificationCommandBatch.cs
@@ -197,7 +197,7 @@ protected override void Consume(RelationalDataReader reader)

                 // Extract result from the command and propagate it

-                var modificationCommand = ModificationCommands[commandIndex++];
+                var modificationCommand = ModificationCommands[commandIndex];

                 if (!(await reader.ReadAsync(cancellationToken).ConfigureAwait(false)))
                 {
@@ -210,6 +210,8 @@ protected override void Consume(RelationalDataReader reader)
                 var valueBufferFactory = CreateValueBufferFactory(modificationCommand.ColumnModifications);
                 modificationCommand.PropagateResults(valueBufferFactory.Create(npgsqlReader));

+                commandIndex++;
+
                 await npgsqlReader.NextResultAsync(cancellationToken).ConfigureAwait(false);
             }
         }

It is similar to version 7

efcore.pg/src/EFCore.PG/Update/Internal/NpgsqlModificationCommandBatch.cs

Lines 149 to 155 in 3fb24ff

	command.PropagateResults(reader);
	commandIndex++;
	onResultSet = async
	? await npgsqlReader.NextResultAsync(cancellationToken).ConfigureAwait(false)
	: npgsqlReader.NextResult();