Re: Empty string property values
On 16.07.2012, at 17:07, Jeremy Booth wrote: For our app we do need to differentiate between provided empty and not provided. I can imagine that this makes sense sometimes (albeit I haven't come across this yet). On 16 July 2012 15:42, Carsten Ziegeler cziege...@apache.org wrote: the handling of the empty value happens in the Sling Post servlet - afaik this was a decision in the early days of the post servlet to treat an empty value like no value. Yes, that was always in the code (I remember refactoring that once for the @Patch feature). It's clearly commented, albeit the initial reasoning seems lost: // if no value is present or a single empty string is given, // just remove the existing property (if any) removeProperty(parent, prop); However, the sling post servlet docs say something different: http://sling.apache.org/site/manipulating-content-the-slingpostservlet-servletspost.html#ManipulatingContent-TheSlingPostServlet%28servlets.post%29-%7B%7B@IgnoreBlanks%7D%7D The 2nd example in that section: form method=POST action=/content/page/first enctype=multipart/form-data input type=hidden name=stringProperty@TypeHint value=String/ input type=text name=stringProperty value=/ /form This will _not_ result in an empty property, but in no property at all (just tested it). Without knowing the original reasoning for == null, I would say the sling post servlet documentation is king and this is a bug :-) But one needs to be careful here, as there are so many options involved: single- vs. multi-value properties, @IgnoreBlanks, @DefaultValue = :null, @DefaultValue = :ignore ... (see also RequestPropertyTest). Cheers, Alex
Empty string property values
Hi If we setup some initial content to have an empty string as a value it goes in to the jcr backend fine, but if we later try to update a value to be an empty string the property gets deleted. I see the @deleted suffix can be added if delete is the required operation (which we do elsewhere), but in this case, we want the value to be present, but blank (empty string). Some digging suggests that the block in SlingPropertyValueHandler is making the decision that blank string means delete. I can't see anything in the jcr specs that suggest a blank string (rather than null) is not valid. Wondering if this is a bug, or I've missed something here. Thanks Jeremy -- Homepage: http://www.computerbooth.com/ Codepage: http://www.newdawnsoftware.com/
RE: Empty string property values
Hi, The relevant section of the spec would appear to be 10.4.2.4 (http://www.day.com/specs/jcr/2.0/10_Writing.html): snip Every property must have a value. The range of property states does not include having a null value, or no value. Setting a property to null is equivalent to removing that property (see §10.9 Removing Nodes and Properties). /snip I wouldn't classify an empty string as either null value or no value myself - unless the type of the property is specified as non-string, in which case it would be no value. Sounds like a bug to me... Cheers, James -Original Message- From: Jeremy Booth [mailto:jer...@computerbooth.com] Sent: 16 July 2012 13:48 To: users@sling.apache.org Subject: Empty string property values Hi If we setup some initial content to have an empty string as a value it goes in to the jcr backend fine, but if we later try to update a value to be an empty string the property gets deleted. I see the @deleted suffix can be added if delete is the required operation (which we do elsewhere), but in this case, we want the value to be present, but blank (empty string). Some digging suggests that the block in SlingPropertyValueHandler is making the decision that blank string means delete. I can't see anything in the jcr specs that suggest a blank string (rather than null) is not valid. Wondering if this is a bug, or I've missed something here. Thanks Jeremy -- Homepage: http://www.computerbooth.com/ Codepage: http://www.newdawnsoftware.com/ Information in this e-mail and any attachments is confidential, and may not be copied or used by anyone other than the addressee, nor disclosed to any third party without our permission. There is no intention to create any legally binding contract or other binding commitment through the use of this electronic communication unless it is issued in accordance with the Experian Limited standard terms and conditions of purchase or other express written agreement between Experian Limited and the recipient. Although Experian has taken reasonable steps to ensure that this communication and any attachments are free from computer virus, you are advised to take your own steps to ensure that they are actually virus free. Companies Act information: Registered name: Experian Limited. Registered office: Landmark House, Experian Way, NG2 Business Park, Nottingham, NG80 1ZZ, United Kingdom. Place of registration: England and Wales. Registered number: 653331
Re: Empty string property values
Hi, the handling of the empty value happens in the Sling Post servlet - afaik this was a decision in the early days of the post servlet to treat an empty value like no value. The question is, does your app have to distinguish between those two cases? When reading values, using the Sling resource api, adapting the resource to a value map and doing a get(prop_name, ) usually does the trick for rendering. Regards Carsten 2012/7/16 Phillpotts, James james.phillpo...@experian.com: Hi, The relevant section of the spec would appear to be 10.4.2.4 (http://www.day.com/specs/jcr/2.0/10_Writing.html): snip Every property must have a value. The range of property states does not include having a null value, or no value. Setting a property to null is equivalent to removing that property (see §10.9 Removing Nodes and Properties). /snip I wouldn't classify an empty string as either null value or no value myself - unless the type of the property is specified as non-string, in which case it would be no value. Sounds like a bug to me... Cheers, James -Original Message- From: Jeremy Booth [mailto:jer...@computerbooth.com] Sent: 16 July 2012 13:48 To: users@sling.apache.org Subject: Empty string property values Hi If we setup some initial content to have an empty string as a value it goes in to the jcr backend fine, but if we later try to update a value to be an empty string the property gets deleted. I see the @deleted suffix can be added if delete is the required operation (which we do elsewhere), but in this case, we want the value to be present, but blank (empty string). Some digging suggests that the block in SlingPropertyValueHandler is making the decision that blank string means delete. I can't see anything in the jcr specs that suggest a blank string (rather than null) is not valid. Wondering if this is a bug, or I've missed something here. Thanks Jeremy -- Homepage: http://www.computerbooth.com/ Codepage: http://www.newdawnsoftware.com/ Information in this e-mail and any attachments is confidential, and may not be copied or used by anyone other than the addressee, nor disclosed to any third party without our permission. There is no intention to create any legally binding contract or other binding commitment through the use of this electronic communication unless it is issued in accordance with the Experian Limited standard terms and conditions of purchase or other express written agreement between Experian Limited and the recipient. Although Experian has taken reasonable steps to ensure that this communication and any attachments are free from computer virus, you are advised to take your own steps to ensure that they are actually virus free. Companies Act information: Registered name: Experian Limited. Registered office: Landmark House, Experian Way, NG2 Business Park, Nottingham, NG80 1ZZ, United Kingdom. Place of registration: England and Wales. Registered number: 653331 -- Carsten Ziegeler cziege...@apache.org
