Introduce custom type mapping for old guid literals.

[robbieknuth]

The entity framework does not parameterize guids when they are put into a "IN" expression. They are generated as literals and put as a part of the SQL. This addresses issue #461 . Ultimately the fix is fairly straight forward: when using the old guid way, override the type mapping to provide an explicit implementation for the literal. I have run some preliminary tests:

Query looks like this:

var records = await context.GuidsTest
    .Where(x => shouldExistListOfGuids.Contains(x.NotNullGuid))
    .ToListAsync();

schema is:

CREATE TABLE `GuidsTest` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `notNullGuid` binary(16) NOT NULL,
  `nullGuid` binary(16) DEFAULT NULL,
  PRIMARY KEY (`id`)

Without the fix, not oldguids:

      SELECT x.Id, x.NotNullGuid, x.NullGuid
      FROM GuidsTest AS x
      WHERE x.NotNullGuid IN ('01234567-1234-1234-1234-123456789012')
Record count: 1

Works as expcted. With the fix, not oldguids:

      SELECT x.Id, x.NotNullGuid, x.NullGuid
      FROM GuidsTest AS x
      WHERE x.NotNullGuid IN ('01234567-1234-1234-1234-123456789012')
Record count: 1

Works as expected. So this does not regress the non-oldguids case.

Without the fix, oldguids (This is the broken one):

      SELECT x.Id, x.NotNullGuid, x.NullGuid
      FROM GuidsTest AS x
      WHERE x.NotNullGuid IN ('01234567-1234-1234-1234-123456789012')
Record count: 0

And finally with the fix, old guids:

      SELECT x.Id, x.NotNullGuid, x.NullGuid
      FROM GuidsTest AS x
      WHERE x.NotNullGuid IN (0x67452301341234121234123456789012)
Record count: 1

Hooray! it works by doing a hex literal. For sanity sake, it also works with nullable guids:

      SELECT x.Id, x.NotNullGuid, x.NullGuid
      FROM GuidsTest AS x
      WHERE x.NullGuid IN (0x47382910291029101029102938475610)
Record count: 1

This fix also introduces a common binary formatter for the guids and the binary data type.

Select code:

var first = await context.BinaryTest
                .Where(x => shouldExistListOfBinaryArrays.Contains(x.BinaryColumn)).ToListAsync();

Schema:

CREATE TABLE `BinaryTest` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `binarycolumn` varbinary(10) NOT NULL,
  PRIMARY KEY (`id`)

Here is it working when empty:

      SELECT x.Id, x.BinaryColumn
      FROM BinaryTest AS x
      WHERE x.BinaryColumn IN (X'')
Binary record count: 1

Note that '0x' would not be valid, so I used the X'' syntax. Binary generation with stuff in it:

      SELECT x.Id, x.BinaryColumn
      FROM BinaryTest AS x
      WHERE x.BinaryColumn IN (0xCAFEBABE)
Binary record count: 1

[AndriySvyryd]

You should call the constructor that takes a RelationalTypeMappingParameters and override the Clone methods. This will make this mapping compatible with new EF features.

[robbieknuth]

Ok updated. I have followed the pattern present in the other classes.

[caleblloyd]

@robbieknuth can you add tests for this functionality?

[robbieknuth]

@caleblloyd Yep. I just wanted to confirm that this approach is actually the right way to be doing this sort of thing (no previous experience with EF provider code) before I did that part of it.

[caleblloyd]

OK great. @AndriySvyryd has the best insight into that. I'd like to get this into 2.1.0, we will likely be looking to do another RC in 2 weeks, then a final release after that if everything checks out.

[PauliusLe]

@caleblloyd When can we expect this to be merged?

[caleblloyd]

It still does not have supporting tests, which is why it hasn't been merged yet. @robbieknuth do you plan to add tests still?

[adomass]

We really need this fix merged asap since we have to do ugly workarounds now in order to deploy with this fix. @caleblloyd Could you somehow merge it?

[caleblloyd]

I went ahead and merged without the tests, could you please validate the behavior is correct in the nightly build:

https://www.myget.org/Package/Details/pomelo?packageType=nuget&packageId=Pomelo.EntityFrameworkCore.MySql

[adomass]

Yes it works with nightly build. When do you plan to release new version?