How to Store BLOB data in Sqlite Using Tcl

Question

I have a Tcl TK application that has a Sqlite back-end. I pretty much understand the syntax for inserting, manipulating, and reading string data; however, I do not understand how to store pictures or files into Sqlite with Tcl.

I do know I have to create a column that holds BLOB data in Sqlite. I just don't know what to do on the Tcl side of things. If anyone knows how to do this or has a good reference to suggest for me, I would really appreciate it.

Thank you,

Damion

Answer 1

In my code, I basically open the file as a binary, load its content into a Tcl variable, and stuff that into the SQLite db. So, something like this...

# load the file's contents
set fileID [open $file RDONLY]
fconfigure $fileID -translation binary
set content [read $fileID}
close $fileID

# store the data in a blob field of the db
$db eval {INSERT OR REPLACE INTO files (content) VALUES ($content)}

Obviously, you'll want to season to taste, and you're table will probably contain additional columns...

Answer 2

The incrblob command looks like what you want: http://sqlite.org/tclsqlite.html#incrblob

The "incrblob" method

This method opens a TCL channel that can be used to read or write into a preexisting BLOB in the database. The syntax is like this:

dbcmd  incrblob  ?-readonly??   ?DB?  TABLE  COLUMN  ROWID 

The command returns a new TCL channel for reading or writing to the BLOB. The channel is opened using the underlying sqlite3_blob_open() C-langauge interface. Close the channel using the close command of TCL.