I am running into a problem mutating a flatbuffer from bytes. According to the flatbuffer documentation (https://github.com/google/flatbuffers/blob/master/docs/source/Tutorial.md), you can mutate fixed size fields, such as an int32. And as you can see below, the generated golang TestMutate has a MutateServerId() function. My problem is that after I mutate it, the bytes don't seem to have changed.
Here is my flatbuffer table definition:
namespace foo;
table TestMutate {
serverId:int32;
}
Here is a unit test I wrote:
func TestMutateFlatbuffer2(test *testing.T) {
builder := flatbuffers.NewBuilder(1024)
packageWalletStorageServicesRPC.TestMutateStart(builder)
packageWalletStorageServicesRPC.TestMutateAddServerId(builder, 1)
endMessage := packageWalletStorageServicesRPC.TestMutateEnd(builder)
builder.Finish(endMessage)
bytes := builder.FinishedBytes()
testMutate := packageWalletStorageServicesRPC.GetRootAsTestMutate(bytes, 0)
success := testMutate.MutateServerId(2)
if !success {
panic("Server id not mutated.")
} else {
logger.Logf(logger.INFO, "serverId mutated to:%d", testMutate.ServerId())
}
mutatedBytes := testMutate.Table().Bytes
if string(mutatedBytes) == string(bytes) {
panic("Bytes were not mutated.")
}
}
Here is the output from the test.
=== RUN TestMutateFlatbuffer2
2019/08/01 19:33:56.801926 foo_test.go:389 : [ I ]: serverId mutated to:2
--- FAIL: TestMutateFlatbuffer2 (0.00s)
panic: Bytes were not mutated. [recovered]
panic: Bytes were not mutated.
Notice that it appears I've mutated the underlying structure, but when I get the bytes of the flatbuffer, they're not changed. Question 1: Am I getting the bytes the correct way? Question 2: If I'm getting them in the right way, why are they not changed since the call to mutate seemed to succeed?