On Apr 26, 4:38 pm, frankz <[email protected]> wrote: > Hi, > in the web2py official book, in the image blog example,
Referring to http://web2py.com/book/default/section/3/6?search=image+blog > Could anyone help explain what the following line mean? > image = db(db.image.id==request.args(0)).select()[0] This example code assume's you've entered an image in the database; if you have not, then the ....select()[0] reference would give you index out of range. Here's why: - This is a database select query; it's form is basically: your_db_connection( WHERE clause; in this case where ID of the image table is same as what requested).select( fields - "ALL" by default) This returns an array of records found in the database - if none, it returns an empty array, []. A more robust way to write this (not used, so the example would be short) would be something like this: images = db(db.image.id==request.args(0)).select() if len(images) == 0: print "No images found!" else: image = images[0] I hope this has been helpful. Regards, - Yarko > > I duplicate the same code but I find URL > htttp://127.0.0.1:8000/images/default/show > gives me an error, "index out of range" > > How do I fix it? > > Thanks, > > -- > Subscription settings:http://groups.google.com/group/web2py/subscribe?hl=en
