TMemoField and UNICODE

[flashDEVART]

Hello
I have in table field with string in UCS2-format
Field type - TMemoField

How I can get a WideString from this field?


Connection Optons-UseUnicode=True
F.AsString return invalid string
GetData return data with broken first 4 chars

PS
Some like in this link
http://www.devart.com/forums/viewtopic. ... 0649#40649

Test on version 5.50

[Dimon]

Please, try to download the latest MyDAC build (5.70.0.44 ) and check if this problem still exists.

[flashDEVART]

Hello
With last MyDAC problem still exists.

I made small test project in D7
http://rapidshare.com/files/190260925/ProjectsUCS.rar

PS: Perhaps, this field does not support work with UNICODE.

In this case questions is:
- what other type of field can be used for storage UNICODE data (in my case)?
- whether I can get access to data in this field as a raw-data?

[Dimon]

In order to keep Unicode data in database you should create a database with utf8 charset, like this:

Code: Select all

CREATE DATABASE test_z CHARACTER SET utf8 COLLATE utf8_general_ci

[flashDEVART]

In order to keep Unicode data in database you should create a database with utf8 charset, like this:

Code: Select all

CREATE DATABASE test_z CHARACTER SET utf8 COLLATE utf8_general_ci

Yes, of course.

Problem - in other:
- TMemoField don't have methods for work with WideStrings direct;
- when I use method LoadFromStream, physically in data in table after each my byte inserted 0-byte.
Of course, I can use SaveToStream and receive initial data recorded by method LoadFromStream.
But if I already have table with data in UCS format, I cannot receive them correctly: methods LoadFromStream deletes each 2nd byte.

May be, this action - not from MyDAC component, may be this is MySQL server options, but I precisely don't know...

PS: Property UseUnicode (from MyDAC) and Transliterate do not give any effect.

[Dimon]

In order to solve this problem you should use the TBlob.AsWideString property to assign WideString to the field, like this:

Code: Select all

Blob := MyQuery1.GetBlob(F);
Blob.AsWideString := StrWString;

[flashDEVART]

In order to solve this problem you should use the TBlob.AsWideString property to assign WideString to the field, like this:

Code: Select all

Blob := MyQuery1.GetBlob(F);
Blob.AsWideString := StrWString;

Yes, this is work as necessary in both directions !!!
Thanks

PS: Additional 0-byte at work through Streams - this is bug?

[Dimon]

PS: Additional 0-byte at work through Streams - this is bug?

Please specify what 0-byte do you mean?

[flashDEVART]

Please specify what 0-byte do you mean?

Example: I have WideChar value $4401

When I use TStream method:
- when I write this value to DB - in DB I see 44-00-01-00 (after each byte inserted additional byte with 0-value)
- when I use TBlob - in DB I see 44-01

[Dimon]

The problem is that when you use TStream Delphi converts WideString to AnsiString and after that it converts this result again to WideString. Therefore you should use the AsWideString property.

[flashDEVART]

The problem is that when you use TStream Delphi converts WideString to AnsiString and after that it converts this result again to WideString. Therefore you should use the AsWideString property.

IMHI, It not correct definition, because in TStream I don't work with types "string"
or "widestring"

var
strWString:WideString;
F :TMemoField;
......
MS := TMemoryStream.Create;
MS.Write(strWString[1], Length(strWString)*2); // widestring like - row-data
MS.Position :=0;
F.LoadFromStream(MS);

[Dimon]

These converts are executed when writing data in internal data structure of TBlob.

[flashDEVART]

These converts are executed when writing data in internal data structure of TBlob.

Not clearly, but can be....
The problem solved.