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I'm trying to write a JSP web app that allows to upload images to a PostgreSQL database. I was following this as a guide, but the image is not uploaded to the DB and the method (below) enters the catch.

This is my code so far:

public boolean upIm() {
    try {
        File file = new File("bg.jpg");
        FileInputStream fis = new FileInputStream(file);
        PreparedStatement ps = con.prepareStatement("INSERT INTO images VALUES (?, ?)");
        ps.setString(1, "background");
        ps.setBinaryStream(2, fis, (int) file.length());
        ps.executeUpdate();
        ps.close();
        fis.close();

        return true;
    } catch (Exception e) {
      e.printStackTrace();
      return false;
    }
}

There seems to be a problem with the FileInputStream, because the statement that goes to the db is INSERT INTO images VALUES ('background', ?) , and I've tested file.length() and it works fine.

That's it; if you need more info or more code please let me know.

EDIT: I get this stacktrace:

org.postgresql.util.PSQLException: ERROR: relation "images" does not exist
   Position: 13
at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2157)
at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1886)
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:255)
at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:555)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:417)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeUpdate(AbstractJdbc2Statement.java:363)
at bd.provaImg.upIm(provaImg.java:50)
at bd.prova2.main(prova2.java:14)

I think position 13 is the line in the class (not shown here) that simply instances the class in which there is this method.

mustieles
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  • Sorry, I should have explained better. The method returns false when called from another class, and of course the image is not inserted into the db. – mustieles Oct 07 '13 at 11:48
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    Stop catching Exception. A exception tells you what's wrong, and where. By catching it and ignoring it, you make it impossible to diagnose the problem. – JB Nizet Oct 07 '13 at 11:50
  • Right, seems kinda obvious now. I'll do that and try to fix whatever error I'm making. Thanks. – mustieles Oct 07 '13 at 11:56
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    writing image into database?! not cool, save the file in file system and save the file path in db. –  Oct 07 '13 at 12:18
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    "Stop catching Exception" should be "stop swallowing Exception" – leonbloy Oct 07 '13 at 13:43

3 Answers3

2

This is your error. Write down 1000 times on a blackboard I will not do such again!.

// BAD BAD BAD BAD BAD BAD BAD
} catch (Exception e) {
  return false;
}

This would be a step closer, but still bad:

// BAD BAD BAD BAD BAD BAD BAD
} catch (Exception e) {
  //NEVER do this. It hides the stacktrace, the main point of logging an error...
  System.err.println(e.getMessage());
  return false;
}

Correctly:

} catch (Exception e) {
  e.printStackTrace();
  return false;
}

Or even better, with a proper logger:

} catch (Exception e) {
  //notice the ",e"! 99.999999% you have to log with full stacktrace!
  LOG.error("Unexpected error during file upload", e);
  return false;
}

You swallowed the error. This is bad. Very-very bad. Such code can be grounds for dismissal...

And now:

  • please post the full stacktrace you get
  • mark the line of the error
ppeterka
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  • Well, now I get an error report but I guess I can work with that. Thank you! (I will not do such thing again!) – mustieles Oct 07 '13 at 11:54
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The stacktrace suggests that table "images" was not found. Some possibilities:
1) "images" is not the right table name; table was created with quotes
2) you need to specify database schema - either in your query (I would first try this), either in your settings file
3) something else in settings file is incorrect

Also, take a look at these posts:
- Java SQL "ERROR: Relation "Table_Name" does not exist"
- PSQLException: ERROR: relation "TABLE_NAME" does not exist

Community
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alterfox
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  • Well, that's embarrassing. The name of the table was "image" in singular and I had "images" in the Java code. It's working now. Thank you! – mustieles Oct 07 '13 at 12:48
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database guy here. This is acceptable for class work but if you store images in a database for a real application with more than a handful of users, you will most likely be sorry and your database will be slow. A preferred pattern is to store filepaths in the database but not image files.

matthudson
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