I use C++ Builder (Delphi 10.2 and C++Builder 10.2 Update 2) and I need a method that, in case there is no particular table, creates it using TADO objects (ADODB)?
I mean TADOQuery, TADOTable, TADOConnection, etc.
How can I do this?
I tried looking at the methods of TADOConncection, of TADOTable, but none of them seem to be useful.
I also tried this route (https://docwiki.embarcadero.com/Libraries/Alexandria/en/Bde.DBTables.TTable.Exists) but there are compatibility problems.
Does this help ?
TADOConnection *YOUR_TADOCONNECTION; // your connection defined earlier in your code
TStringList *TableList = new TStringList;
bool WithSystemTables = true; // or false according to your requirements
YOUR_TADOCONNECTION->GetTableNames(TableList, WithSystemTables);
for (int i = 0 i < TableList->Count(); i++) {
String NextTableName = TableList->Strings[i];
/*.... your check for the table name being the one you want goes here .... */
}
delete TableList;
Related
I am currently porting an UWP application from C++/CX to C++/WinRT. I encountered a safe_cast<Platform::IBoxArray<byte>^>(data) where data is of type Windows::Foundation::IInspectable ^.
I know that the safe_cast is represented by the as<T> method, and I know there are functions for boxing (winrt::box_value) and unboxing (winrt::unbox_value) in WinRT/C++.
However, I need to know the equivalent of Platform::IBoxArray in order to perform the cast (QueryInterface). According to https://learn.microsoft.com/de-de/cpp/cppcx/platform-iboxarray-interface?view=vs-2017, IBoxArray is the C++/CX equivalent of Windows::Foundation::IReferenceArray, but there is no winrt::Windows::Foundation::IReferenceArray...
Update for nackground: What I am trying to achieve is retrieving the view transform attached by the HoloLens to every Media Foundation sample from its camera. My code is based on https://github.com/Microsoft/HoloLensForCV, and I got really everything working except for this last step. The problem is located around this piece of code:
static const GUID MF_EXTENSION_VIEW_TRANSFORM = {
0x4e251fa4, 0x830f, 0x4770, 0x85, 0x9a, 0x4b, 0x8d, 0x99, 0xaa, 0x80, 0x9b
};
// ...
// In the event handler, which receives const winrt::Windows::Media::Capture::Frames::MediaFrameReader& sender:
auto frame = sender.TryAcquireLatestFrame();
// ...
if (frame.Properties().HasKey(MF_EXTENSION_VIEW_TRANSFORM)) {
auto /* IInspectable */ userData = frame.Properties().Lookup(MF_EXTENSION_VIEW_TRANSFORM);
// Now I would have to do the following:
// auto userBytes = safe_cast<Platform::IBoxArray<Byte> ^>(userData)->Value;
//viewTransform = *reinterpret_cast<float4x4 *>(userBytes.Data);
}
I'm also working on porting some code from HoloLensForCV to C++/WinRT. I came up with the following solution for a very similar case (but not the exact same line of code you ask about):
auto user_data = source.Info().Properties().Lookup(c_MF_MT_USER_DATA); // type documented as 'array of bytes'
auto source_name = user_data.as<Windows::Foundation::IReferenceArray<std::uint8_t>>(); // Trial and error to get the right specialization of IReferenceArray
winrt::com_array<std::uint8_t> arr;
source_name.GetUInt8Array(arr);
winrt::hstring source_name_str{ reinterpret_cast<wchar_t*>(arr.data()) };
Specifically, you can replace the safe_cast with .as<Windows::Foundation::IReferenceArray<std::uint8_t> for a boxed array of bytes. Then, I suspect doing the same cast as me (except to float4x4* instead of wchar_t*) will work for you.
The /ZW flag is not required for my example above.
I can't believe that actually worked, but using information from https://learn.microsoft.com/de-de/windows/uwp/cpp-and-winrt-apis/interop-winrt-cx, I came up with the following solution:
Enable "Consume Windows Runtime Extension" via /ZW and use the following conversion:
auto abi = reinterpret_cast<Platform::Object ^>(winrt::get_abi(userData));
auto userBytes = safe_cast<Platform::IBoxArray<byte> ^>(abi)->Value;
viewTransform = *reinterpret_cast<float4x4 *>(userBytes->Data);
Unfortunately, the solution has the drawback of generating
warning C4447: 'main' signature found without threading model. Consider using 'int main(Platform::Array^ args)'.
But for now, I can live with it ...
I need to make signed requests to AWS ES, but am stuck at the first hurdle in that I cannot seem to be able to use CurlHttpClient. Here is my code (verb, path, and body defined elsewhere):
Aws::Client::ClientConfiguration clientConfiguration;
clientConfiguration.scheme = Aws::Http::Scheme::HTTPS;
clientConfiguration.region = Aws::Region::US_EAST_1;
auto client = Aws::MakeShared<Aws::Http::CurlHttpClient>(ALLOCATION_TAG, clientConfiguration);
Aws::Http::URI uri;
uri.SetScheme(Aws::Http::Scheme::HTTPS);
uri.SetAuthority(ELASTIC_SEARCH_DOMAIN);
uri.SetPath(path);
Aws::Http::Standard::StandardHttpRequest req(uri, verb);
req.AddContentBody(body);
auto res = client->MakeRequest(req);
Aws::Http::HttpResponseCode resCode = res->GetResponseCode();
if (resCode == Aws::Http::HttpResponseCode::OK) {
Aws::IOStream &body = res->GetResponseBody();
rejoiceAndBeMerry();
}
else {
gotoPanicStations();
}
When executed, the code throws a bad_function_call deep from within the sdk mixed up with a lot of shared_ptr this and allocate that. My guess is that I am just using the SDK wrong, but I've been unable to find any examples that use the CurlHttpClient directly such as I need to do here.
How can I use CurlHttpClient?
You shouldn't be using the HTTP client directly, but the supplied wrappers with the aws-cpp-sdk-es package. Like previous answer(s), I would recommend evaluating the test cases shipped with the library to see how the original authors intended to implement the API (at least until the documents catch-up).
How can I use CurlHttpClient?
Your on the right track with managed shared resources and helper functions. Just need to create a static factory/client to reference. Here's a generic example.
using namespace Aws::Client;
using namespace Aws::Http;
static std::shared_ptr<HttpClientFactory> MyClientFactory; // My not be needed
static std::shared_ptr<HttpClient> MyHttpClient;
// ... jump ahead to method body ...
ClientConfiguration clientConfiguration;
MyHttpClient = CreateHttpClient(clientConfiguration);
Aws::String uri("https://example.org");
std::shared_ptr<HttpRequest> req(
CreateHttpRequest(uri,
verb, // i.e. HttpMethod::HTTP_POST
Utils::Stream::DefaultResponseStreamFactoryMethod));
req.AddContentBody(body); //<= remember `body' should be `std::shared_ptr<Aws::IOStream>',
// and can be created with `Aws::MakeShared<Aws::StringStream>("")';
req.SetContentLength(body_size);
req.SetContentType(body_content_type);
std::shared_ptr<HttpResponse> res = MyHttpClient->MakeRequest(*req);
HttpResponseCode resCode = res->GetResponseCode();
if (resCode == HttpResponseCode::OK) {
Aws::StringStream resBody;
resBody << res->GetResponseBody().rdbuf();
rejoiceAndBeMerry();
} else {
gotoPanicStations();
}
I encountered exactly the same error when trying to download from S3 using CurlHttpClient.
I fixed it by instead modelling my code after the integration test found in the cpp sdk:
aws-sdk-cpp/aws-cpp-sdk-s3-integration-tests/BucketAndObjectOperationTest.cpp
Search for the test called TestObjectOperationsWithPresignedUrls.
I've spent three days trying to figure out this, any help would be appreciated. I'm trying to open few tables (stored in InnoDB format) within the UDF in MySQL. I'm able to open them if I create a new THD instance and set it to be the "current thd". However, I'm having problem to properly close these tables. The code I used to open the tables looks like this
THD *thd = new THD;
thd->thread_stack = (char*) &thd;
thd->set_db(db_name, strlen(db_name));
my_pthread_setspecific_ptr(THR_THD, thd);
const unsigned int NUMBER_OF_TABLES = 5;
char* tableNames[NUMBER_OF_TABLES];
... set table name here ...
TABLE_LIST tables[NUMBER_OF_TABLES];
for (unsigned int i = 0; i < NUMBER_OF_TABLES; i++)
{
tables[i].init_one_table((char*)db_name, strlen(db_name), tableNames[i],
strlen(tableNames[i]), tableNames[i], TL_WRITE_ALLOW_WRITE);
if (i != NUMBER_OF_TABLES-1)
tables[i].next_local = tables[i].next_global = tables + 1 + i;
}
}
if (open_and_lock_tables(thd, tables, false, MYSQL_LOCK_IGNORE_TIMEOUT))
{
goto end;
}
I was able to open all tables using the above code block. However, when I finish using them, I was not able to close these tables since assertion fails. I would appreciate if anyone can help with these. I use the following code block to close the tables,
thd->cleanup_after_query();
close_thread_tables(thd);
delete thd;
The failed assertion was to do with the thd->transaction.stmt.is_empty().
The is_empty() method simply checks whether ha_list == NULL.
I would like to understand how can I properly close these tables??
I'm developing on Windows 7 with MySQL 5.6.
My problem requires me to dynamically add where clauses to a IQueryable based on user input. The problem i'm having is that Linq-to-SQL doesn't seem to like having multiple where clauses on the same field, it actually duplicates the search arg value for the last item on all parameters. I verified this behavior through a SQL trace. Here is what I'm seeing.
WHERE ([t22].[OpenText] LIKE #p11) AND ([t22].[OpenText] LIKE #p12)
-- #p11: Input NVarChar (Size = 10; Prec = 0; Scale = 0) [%classify%] // Should be 2da57652-dcdf-4cc8-99db-436c15e5ef50
-- #p12: Input NVarChar (Size = 10; Prec = 0; Scale = 0) [%classify%]
My code uses a loop to dynamically add the where clauses as you can see below. My question is how do I work around this? This pretty much seems like a bug with the tool, no?
// add dyanmic where clauses based on user input.
MatchCollection searchTokens = Helper.ExtractTokensWithinBracePairs(filterText);
if (searchTokens.Count > 0)
{
foreach(Match searchToken in searchTokens)
query = query.Where((material => material.OpenText.Contains(searchToken.Value)));
}
else
{
query = query.Where((material => material.OpenText.Contains(filterText)));
}
Closing over the loop variable considered harmful! Change
foreach(Match searchToken in searchTokens) {
query = query.Where(
material => material.OpenText.Contains(searchToken.Value)
);
}
to
foreach(Match searchToken in searchTokens) {
Match token = searchToken;
query = query.Where(
material => material.OpenText.Contains(token.Value)
);
}
You are closing over the loop variable, which is considered harmful. To fix do this:
foreach(Match searchToken in searchTokens)
{
Match searchToken2 = searchToken;
// ^^^^^^^^^^^^ copy the value of the reference to a local variable.
query = query.Where(material => material.OpenText.Contains(searchToken2.Value));
// use the copy here ^^^^^^^^^^^^
}
The reason why your version doesn't work is that the query refers to the variable searchToken, not the value it had when the query was created. When the variable's value changes, all your queries see the new value.
I don't have enough rep to leave comments yet (or this would be a comment and not an answer) but the answers listed here worked for me.
However, I had to turn off compiler optimizations in order for it to work. If you do not turn off compiler optimizations (at least at the method level) then the compiler sees you setting a loop variable to a local variable and throws the local variable away.
I m just starting with microsoft (MVC,C#, LINQ), so far so good, but i have a question about LINQ uses, How do i get the value form a LINQ like this one?
var x = from a in db.tablex
where a.eventID == eventID
select new
{
owner = a.owner,
shipper = a.shipper,
consignee = a.consignee
};
I try something like "r.owner" inside a foreach to get the value retrieved from DB
foreach (var r in x)
but its not working.. i dont get intellisense either.. how do i get the value??. I saw several examples and it seems to work like this, but for some reason its not working.. Thanks
Ok guys here was the thing, (it wasnt the typo it was just in the post), i was missing a using :
using System.Reflection;
with this C# automatically creates a class from them, and now it works
What a noob of me =).
foreach (var r in x)
{
var owner = r.owner;// not x.owner
}