A PDF is a binary blob and contains characters that would not be valid
UTF8. new Buffer(mySqlData).toString('utf8') is going to replace all
unknown bytes/character codes with character 0xFFFD.
What exactly do you want on the client? If you said you used base64
encoding successfully, I'm guessing maybe you want a string in which the
Nth character's charCode is equal to the Nth byte of your binary data? The
UTF8 encoding of this won't look like your binary data, but that should be
fine. To get that, you first want to construct such a string on your
server, then send that to the client (using UTF8 encoding should be fine
for transfer, as, for example, UTF8 character 0xFF is represented by
0xC3BF, it's going to be a bit larger than sending binary directly to the
client, but still smaller than base64 encoding for most characters).
You should be able to construct such a string on your server with either of
these (depending on what exactly "mySqlData" is, I'm assuming an array of
bytes or a Buffer):
for (var s1='', ii=0; ii<mySqlData.length; ++ii) { s1 +=
String.fromCharCode(mySqlData[ii]); }
var s2 = new Buffer(mySqlData).toString('binary');
assert.equal(s1, s2);
Now you have a string, which can be sent losslessly through utf8 encoding,
which represents your bytes.
On the client, if you actually want an array of bytes again, then loop
through the string and call charCodeAt. Note that making a new Buffer or
Uint8Array from this kind of string (without specifying this "binary"
encoding which is not particularly a standard) will not work, because that
will get you the UTF-8 encoded bytes, not your source bytes.
None of this sounds particularly efficient, the best would be to simply
send the file as binary, without any extra encoding.
Hope this helps,
Jimb
On Wednesday, September 30, 2015 at 7:53:09 AM UTC-7, arpit shah wrote:
>
> Hi All,
>
> I have been facing an issue on node.js express framework encoding/decoding
> style.
> Brief background, I store pdf file in mysql database with longblob
> data-type with latin1 charset. From server side, i need to send the binary
> data with UTF8 Encoding format as my client knows utf8 decoding format only.
> I tried all the possible solutions available on google.
>
> For ex: new Buffer(mySqlData).toString('utf8');
> Already tried module "UTF8" with given functionality
> utf8.encode(mySqlData);
>
> Also i already tried "base64" encoding and retrieve data at client with
> base64 decoding. I is working just fine but i need to have utf8 encoding
> set. Also you know base64 certainly increase the size.
>
> Please help guys.
>
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