February 2003 - tdwg-content

Re: XML: How to require either or both of two child elements, but prevent both missing?
by Nozomi Ytow 24 Feb '03

24 Feb '03

rousse> I guess you're thinking of making A and B member of Child substitution group, rousse> and requiring a sequence of 1 to 2 Child element in parent ? Yes, although maxOccurs was unclear for me (might be nubmer of possible characters). rousse> It won't solve rousse> the problem of two A or two B, as any other constraint considering child rousse> element separatly. Ah. I didn't read Gregor's description as excluding multiplication of children; is it trouble if the Parent has multiple children, Gregor? -- James

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Re: XML: How to require either or both of two child elements, but prevent both missing?
by Guillaume Rousse 23 Feb '03

23 Feb '03

Le Samedi 22 Février 2003 23:58, vous avez écrit : > jrc> How about changing the model to 'choice' and requiring one but > allowing two jrc> (or multiple) occurrences of optional elements? > jrc> something like this maybe? > > > jrc> <xs:choice minOccurs="1" maxOccurs="2"> > jrc> <xs:element name="A" minOccurs="0" maxOccurs="1"/> > jrc> <xs:element name="B" minOccurs="0" maxOccurs="1"/> > jrc> </xs:choice> > > Dosn't it alllow the choice whithout A nor B for their minOccurs=0? Just set minOccurs to 1 then. However, nothing prevent you from two A or two B then. > Substition group would do. I guess you're thinking of making A and B member of Child substitution group, and requiring a sequence of 1 to 2 Child element in parent ? It won't solve the problem of two A or two B, as any other constraint considering child element separatly. -- If a program actually fits in memory and has enough disk space, it is guaranteed to crash. -- Murphy's Computer Laws n°5

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Re: XML: How to require either or both of two child elements, but prevent both missing?
by Guillaume Rousse 23 Feb '03

23 Feb '03

Le Dimanche 23 Février 2003 09:26, vous avez écrit : > Wouldn't this example too would allow for 2 B's? It may be messy > (especially if you progress beyond two elements), but couldn't you just use > a choice allowing for only one of an A-B group, an A or a B? That was also my idea (see attached files), however it is prohibited for ambiguous content model: when the parser reach element A, he can't determine wether it is a single A element or part of AB group. Reversing A and B order in group won't fix the problem, but anything else that would allows to distinguish them would. Gregor, could we have a bit more context ? -- No matter how good of a deal you get on computer components, the price will always drop immediately after the purchase. -- Murphy's Computer Laws n°7

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Re: XML: How to require either or both of two child elements, but prevent both missing?
by Pavel Benda 23 Feb '03

23 Feb '03

Hi all once more, if there is a problem of messy schema or complexity of this approach for developers, it is possible to add "processing" validation layer using Schematron or XSLT template - simply by adding the Schematron or XSLT code to xs:appinfo element of schema documentation. The application can parse schema, read code and execute it and report results of additional validation to user (or to some process). To catch such problems by Schematron or XSLT is deadly simple. And more, we can meet worse problems, where the XML schema is absolutely unusable - for example, dependence "if element A has value X, then value of element B must fall between Y and Z". In such case, Schematron and XSLT approach is only possible. Moreover, it is possible to include all such dependencies into one Schematron/XSLT code. Pavel Benda Czech Collection of Microorganisms pavelben(a)sendme.cz

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Re: XML: How to require either or both of two child elements, but prevent both missing?
by Pavel Benda 23 Feb '03

23 Feb '03

Hi all, I suppose William Ullate is right way; nevertheless, his example isn't completed and doesn't work. The correct syntax of William code is here: <?xml version="1.0" encoding="UTF-8"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified"> <xs:element name="Parent"> <xs:complexType> <xs:choice> <xs:group ref="elementAoptB"/> <xs:element ref="elementB" minOccurs="1"/> </xs:choice> </xs:complexType> </xs:element> <xs:group name="elementAoptB"> <xs:sequence> <xs:element name="elementA" minOccurs="1"/> <xs:element ref="elementB" minOccurs="0"/> </xs:sequence> </xs:group> <xs:element name="elementB"/> </xs:schema> This work fine. Pavel Benda Czech Collection of Microorganisms pavelben(a)sendme.cz

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Re: XML: How to require either or both of two child elements, but prevent both missing?
by unknown＠example.com 23 Feb '03

23 Feb '03

Hello Donald: I'm sorry, I have to say I really don´t know because I haven´t tried it out. I just thought it wouldn't allow for 2 B's if you had to choose first between an A[B] element and a B element. But anyway I couldn't agree more with you: it surely gets too messy, specially if it's one of the first elements in the hierarchy, as this seems the case. See you next week, William. -----Original Message----- From: Hobern, Donald [mailto:DHobern@GBIF.ORG] Sent: Domingo 23 de Febrero de 2003 02:26 AM To: TDWG-SDD(a)USOBI.ORG Subject: Re: XML: How to require either or both of two child elements, but prevent both missing? Wouldn't this example too would allow for 2 B's? It may be messy (especially if you progress beyond two elements), but couldn't you just use a choice allowing for only one of an A-B group, an A or a B? Donald Hobern -----Original Message----- From: William Ulate To: TDWG-SDD(a)USOBI.ORG Sent: 23/02/03 00:08 Subject: Re: XML: How to require either or both of two child elements, but prevent both missing? Importance: High Hello: Wouldn´t this allow for the case when there are two A's or two B's? I haven't tried it yet but, I just glanced at the spec and found an example that would yield something like this if applied: <?xml version="1.0" encoding="UTF-8"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified"> <xs:element name="Parent"> <xs:complexType> <xs:choice> <xs:group ref="elementABopt"/> <xs:element ref="elementB" minOccurs="1"/> </xs:choice> </xs:complexType> </xs:element> <xs:element name="elementABopt"> <xs:complexType> <xs:sequence> <xs:element ref="elementA" minOccurs="1"/> <xs:element ref="elementB" minOccurs="0"/> </xs:sequence> </xs:complexType> </xs:element> <xs:element name="elementA"> </xs:element> <xs:element name="elementB"> </xs:element> </xs:schema> Do you see any problem here (besides complexity?) Hope this helps... Greetings, William. -----Original Message----- From: Jim Croft [mailto:jrc@ANBG.GOV.AU] Sent: Sábado 22 de Febrero de 2003 04:43 PM To: TDWG-SDD(a)USOBI.ORG Subject: Re: XML: How to require either or both of two child elements, but prevent both missing? >How in XML-schema do you make sure that of two possible child >elements, either or both, but not neither are present? How about changing the model to 'choice' and requiring one but allowing two (or multiple) occurrences of optional elements? something like this maybe? <?xml version="1.0" encoding="UTF-8"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified"> <xs:element name="Parent"> <xs:complexType> <xs:choice minOccurs="1" maxOccurs="2"> <xs:element name="A" minOccurs="0" maxOccurs="1"/> <xs:element name="B" minOccurs="0" maxOccurs="1"/> </xs:choice> </xs:complexType> </xs:element> </xs:schema> ~ Jim Croft ~ jrc(a)anbg.gov.au ~ 02-62465500 ~ www.anbg.gov.au/jrc/ ~

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Re: XML: How to require either or both of two child elements, but prevent both missing?
by Jim Croft 23 Feb '03

23 Feb '03

>How in XML-schema do you make sure that of two possible child >elements, either or both, but not neither are present? How about changing the model to 'choice' and requiring one but allowing two (or multiple) occurrences of optional elements? something like this maybe? <?xml version="1.0" encoding="UTF-8"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified"> <xs:element name="Parent"> <xs:complexType> <xs:choice minOccurs="1" maxOccurs="2"> <xs:element name="A" minOccurs="0" maxOccurs="1"/> <xs:element name="B" minOccurs="0" maxOccurs="1"/> </xs:choice> </xs:complexType> </xs:element> </xs:schema> ~ Jim Croft ~ jrc(a)anbg.gov.au ~ 02-62465500 ~ www.anbg.gov.au/jrc/ ~

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Re: XML: How to require either or both of two child elements, but prevent both missing?
by Hobern, Donald 23 Feb '03

23 Feb '03

Wouldn't this example too would allow for 2 B's? It may be messy (especially if you progress beyond two elements), but couldn't you just use a choice allowing for only one of an A-B group, an A or a B? Donald Hobern -----Original Message----- From: William Ulate To: TDWG-SDD(a)USOBI.ORG Sent: 23/02/03 00:08 Subject: Re: XML: How to require either or both of two child elements, but prevent both missing? Importance: High Hello: Wouldn´t this allow for the case when there are two A's or two B's? I haven't tried it yet but, I just glanced at the spec and found an example that would yield something like this if applied: <?xml version="1.0" encoding="UTF-8"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified"> <xs:element name="Parent"> <xs:complexType> <xs:choice> <xs:group ref="elementABopt"/> <xs:element ref="elementB" minOccurs="1"/> </xs:complexType> </xs:element> <xs:element name="elementAoptB"> <xs:complexType> <xs:sequence> <xs:element ref="elementA" minOccurs="1"/> <xs:element ref="elementB" minOccurs="0"/> </xs:sequence> </xs:complexType> </xs:element> <xs:element name="elementA"> </xs:element> <xs:element name="elementB"> </xs:element> </xs:schema> Do you see any problem here (besides complexity?) Hope this helps... Greetings, William. -----Original Message----- From: Jim Croft [mailto:jrc@ANBG.GOV.AU] Sent: Sábado 22 de Febrero de 2003 04:43 PM To: TDWG-SDD(a)USOBI.ORG Subject: Re: XML: How to require either or both of two child elements, but prevent both missing? >How in XML-schema do you make sure that of two possible child >elements, either or both, but not neither are present? How about changing the model to 'choice' and requiring one but allowing two (or multiple) occurrences of optional elements? something like this maybe? <?xml version="1.0" encoding="UTF-8"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified"> <xs:element name="Parent"> <xs:complexType> <xs:choice minOccurs="1" maxOccurs="2"> <xs:element name="A" minOccurs="0" maxOccurs="1"/> <xs:element name="B" minOccurs="0" maxOccurs="1"/> </xs:choice> </xs:complexType> </xs:element> </xs:schema> ~ Jim Croft ~ jrc(a)anbg.gov.au ~ 02-62465500 ~ www.anbg.gov.au/jrc/ ~

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Re: XML: How to require either or both of two child elements, but prevent both missing?
by Nozomi Ytow 23 Feb '03

23 Feb '03

jrc> How about changing the model to 'choice' and requiring one but allowing two jrc> (or multiple) occurrences of optional elements? jrc> something like this maybe? jrc> <xs:choice minOccurs="1" maxOccurs="2"> jrc> <xs:element name="A" minOccurs="0" maxOccurs="1"/> jrc> <xs:element name="B" minOccurs="0" maxOccurs="1"/> jrc> </xs:choice> Dosn't it alllow the choice whithout A nor B for their minOccurs=0? Substition group would do. Cheers, James

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XML: How to require either or both of two child elements, but prevent both missing?
by Gregor Hagedorn 22 Feb '03

22 Feb '03

How in XML-schema do you make sure that of two possible child elements, either or both, but not neither are present? Parent A Parent B Parent A B should all be ok, but not Parent without either A or B. Attached is a small ZIP file with example files. Paris was a good meeting, I am working on the minutes! Thanks! Gregor ---------------------------------------------------------- Gregor Hagedorn (G.Hagedorn(a)bba.de) Institute for Plant Virology, Microbiology, and Biosafety Federal Research Center for Agriculture and Forestry (BBA) Koenigin-Luise-Str. 19 Tel: +49-30-8304-2220 14195 Berlin, Germany Fax: +49-30-8304-2203 Often wrong but never in doubt! The following section of this message contains a file attachment prepared for transmission using the Internet MIME message format. If you are using Pegasus Mail, or any another MIME-compliant system, you should be able to save it or view it from within your mailer. If you cannot, please ask your system administrator for assistance. ---- File information ----------- File: ParentChildABProblem.zip Date: 22 Feb 2003, 18:37 Size: 1639 bytes. Type: ZIP-archive

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