You are viewing a plain text version of this content. The canonical link for it is here.
Posted to users@daffodil.apache.org by "Horvath, Attila J CTR (USA)" <at...@mail.mil> on 2021/07/21 12:04:45 UTC
variable length CSV records via 'lengthKind' property
ALCON - see attached PDF version of this message
I have a Character Separated Values [CSV] ASCII input file where:
- fields are ASCII STX character [0x02] separated
- variable number of fields per below
- records are ASCII DC4 character [0x14] terminated
- file is ASCII EOT character [0x04] terminated
In following sample excerpt, highlighted in YELLOW is last record of data file.
3rd field [31 30] specifies 10 fields to follow each STX [0x02] delimited,
followed by record and file terminators [0x14 0x04] respectively...
[cid:ii_krded6hx1]
Is it possible to read the 3rd field ['10'], save it via [dfdl:lengthKind and/or dfdl:defineVariable] as "NUM_FIELDS" and pass that value to 'maxOccurs' attribute on per record basis?
EG:...
<xs:element name="parameters" maxOccurs=NUM_FIELDS minOccurs="1">
...
</xs:element>
Thx in advance
Attila
Re: variable length CSV records via 'lengthKind' property
Posted by Attila Horvath <at...@gmail.com>.
Thx Steve.
I'll give it a shot.
Will probably have some follow up questions when I reach that bridge.
Attila
On Wed, Jul 21, 2021 at 9:52 AM Steve Lawrence <sl...@apache.org> wrote:
> You cannot dynamically set maxOccurs--that has to be either a static
> number or "unbounded". This is a restriction of XML Schema that DFDL is
> based off of.
>
> But Daffodil does support what you're trying to do . First, you'll want
> to set maxOccurs="unbounded" (since we don't know how many parameter
> instances there might be). Bbut then we can use the
> dfdl:occursCountKind="expression" and dfdl:occursCount properties to
> evaluate an expression at parse time to set the number of occurrences to
> the value of the third field. For example:
>
> ...
> <xs:element name="field3" type="xs:int" ... />
> <xs:element name="parameters" type="..." maxOccurs="unbounded"
> dfdl:occursCountKind="expression"
> dfdl:occursCount="{ ../field3 }" ... />
> ...
>
> So we parse field3 to an integer and then use that value in an
> expression to determine the number of occurrences of the parameters array.
>
>
> On 7/21/21 8:04 AM, Horvath, Attila J CTR (USA) wrote:
> > ALCON - see attached PDF version of this message
> >
> > I have a Character Separated Values [CSV] ASCII input file where:
> >
> > - fields are ASCII STX character [0x02] separated
> >
> > - variable number of fields per below
> >
> > - records are ASCII DC4 character [0x14] terminated
> >
> > - file is ASCII EOT character [0x04] terminated
> >
> > In following sample excerpt, highlighted in YELLOW is last record of
> data file.
> >
> > 3rd field [31 30] specifies 10 fields to follow each STX [0x02]
> delimited,
> >
> > followed by record and file terminators [0x14 0x04] respectively...
> >
> > Is it possible to read the 3rd field ['10'], save it via
> [*_dfdl:lengthKind_*
> > and/or *_dfdl:defineVariable_*] as "NUM_FIELDS" and pass that value to
> > 'maxOccurs' attribute on per record basis?
> >
> > EG:...
> >
> > <xs:element name="parameters" maxOccurs=NUM_FIELDS minOccurs="1">
> >
> > ...
> >
> > </xs:element>
> >
> > Thx in advance
> >
> > Attila
> >
>
>
Re: variable length CSV records via 'lengthKind' property
Posted by "Beckerle, Mike" <mb...@owlcyberdefense.com>.
I think we can conclude this as a DFDL rule/practice:
If optional leading zeros or optional trailing zeros must be preserved then the type should be string, not a numeric type.
Why: 01 and 1 are equivalent integers. But they're not equivalent text strings. If this difference matters to the data format (saying "must be preserved" in a parse-unparse cycle is the same as saying this difference matters to the format), you must capture this difference in the way you model this data.
If you always want the leading zeros, you can specify required leading zeros on the text form of an integer with textNumberPattern, but then they're not optional, they're always there when unparsing.
There is no way in DFDL to say "it's an integer, but if there are leading zeros when parsing, I consider that's a different integer than if there aren't, so remember that for use when unparsing." The DFDL Infoset for an integer has no such concept or place to remember that. In some sense the point of saying something is an integer in a data format is to express that these sorts of things are not​ significant to the format, so unparsing them to a canonical text representation of an integer is the preferred thing.
You can interpret the text string as an integer by calling a conversion function such as xs:integer(...).
A similar issue comes up with trailing zeros in decimal and floating-point numbers. If trailing zeros are optional, but "must be preserved", then they are part of the format, and must appear in the infoset if they are to be preserved.
The type should be xs:string, not xs:decimal, xs:float, or xs:double.
A similar but more obscure case arises in dates. Feb 29 in a non-leap year is the same as Mar 1. The infoset doesn't capture this. On unparse type xs:date will output "Mar 1". If you want the infoset to somehow remember the string, then well, it's a string.
________________________________
From: Attila Horvath <at...@gmail.com>
Sent: Friday, July 30, 2021 1:13 PM
To: users@daffodil.apache.org <us...@daffodil.apache.org>
Subject: Re: variable length CSV records via 'lengthKind' property
EXCELLENT!!! That fits the bill...
<xs:element name="fields" minOccurs="1" maxOccurs="1">
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:pattern value="[0-9]{1,2}"/>
</xs:restriction>
</xs:simpleType>
</xs:element>
<xs:element name="field" maxOccurs="unbounded"
dfdl:occursCount="{ xs:unsignedInt(../fields) }" dfdl:occursCountKind="expression">
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:pattern value="[a-zA-Z0-9+=]{0,64}"/>
</xs:restriction>
</xs:simpleType>
</xs:element>
Thx again... after the fact.
Attila
On Fri, Jul 30, 2021 at 12:55 PM Beckerle, Mike <mb...@owlcyberdefense.com>> wrote:
Model the length field as a string so its characters are perfectly preserved.
Where you need to use its value in the number of occurrences, call the xs:unsignedInt(...) function on the string value.
________________________________
From: Attila Horvath <at...@gmail.com>>
Sent: Friday, July 30, 2021 12:48 PM
To: users@daffodil.apache.org<ma...@daffodil.apache.org> <us...@daffodil.apache.org>>
Subject: Re: variable length CSV records via 'lengthKind' property
Thx to all responses. Got variable length record w/ variable number of 'specified' fields working EXCEPT unparsing does not yield "lossless" reconstituted data.
Per...
<xs:element name="fields" type="xs:unsignedInt"/>
"fields" specifies number of fields in record. When "fields" has value "1", unparse yields lossless result. However, when "fields" has value "01", unparse yields lossful "1" result dropping the leading zero.
Suggestions to resolve? Our solution MUST be lossless.
Thx in advance
Attila
On 2021/07/21 14:01:12, "Beckerle, Mike" <mb...@owlcyberdefense.com>> wrote:
> There is an example of doing dfdl:occursCountKind 'expression' on github in the CSV example here:
>
> https://github.com/DFDLSchemas/CSV/blob/master/src/main/resources/com/tresys/csv/xsd/csvHeaderEnforced.dfdl.xsd
>
> Line 75 of this file, it uses this technique to ensure each row has the same number of items as there were titles in the initial header row. Your case you want a different expression to pick out the exact count from an earlier element, but the example may help.
>
>
>
> ________________________________
> From: Steve Lawrence <sl...@apache.org>>
> Sent: Wednesday, July 21, 2021 9:52 AM
> To: users@daffodil.apache.org<ma...@daffodil.apache.org> <us...@daffodil.apache.org>>
> Subject: Re: variable length CSV records via 'lengthKind' property
>
> You cannot dynamically set maxOccurs--that has to be either a static
> number or "unbounded". This is a restriction of XML Schema that DFDL is
> based off of.
>
> But Daffodil does support what you're trying to do . First, you'll want
> to set maxOccurs="unbounded" (since we don't know how many parameter
> instances there might be). Bbut then we can use the
> dfdl:occursCountKind="expression" and dfdl:occursCount properties to
> evaluate an expression at parse time to set the number of occurrences to
> the value of the third field. For example:
>
> ...
> <xs:element name="field3" type="xs:int" ... />
> <xs:element name="parameters" type="..." maxOccurs="unbounded"
> dfdl:occursCountKind="expression"
> dfdl:occursCount="{ ../field3 }" ... />
> ...
>
> So we parse field3 to an integer and then use that value in an
> expression to determine the number of occurrences of the parameters array.
>
>
> On 7/21/21 8:04 AM, Horvath, Attila J CTR (USA) wrote:
> > ALCON - see attached PDF version of this message
> >
> > I have a Character Separated Values [CSV] ASCII input file where:
> >
> > - fields are ASCII STX character [0x02] separated
> >
> > - variable number of fields per below
> >
> > - records are ASCII DC4 character [0x14] terminated
> >
> > - file is ASCII EOT character [0x04] terminated
> >
> > In following sample excerpt, highlighted in YELLOW is last record of data file.
> >
> > 3rd field [31 30] specifies 10 fields to follow each STX [0x02] delimited,
> >
> > followed by record and file terminators [0x14 0x04] respectively...
> >
> > Is it possible to read the 3rd field ['10'], save it via [*_dfdl:lengthKind_*
> > and/or *_dfdl:defineVariable_*] as "NUM_FIELDS" and pass that value to
> > 'maxOccurs' attribute on per record basis?
> >
> > EG:...
> >
> > <xs:element name="parameters" maxOccurs=NUM_FIELDS minOccurs="1">
> >
> > ...
> >
> > </xs:element>
> >
> > Thx in advance
> >
> > Attila
> >
>
>
Re: variable length CSV records via 'lengthKind' property
Posted by Attila Horvath <at...@gmail.com>.
EXCELLENT!!! That fits the bill...
<xs:element name="fields" minOccurs="1" maxOccurs="1">
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:pattern value="[0-9]{1,2}"/>
</xs:restriction>
</xs:simpleType>
</xs:element>
<xs:element name="field" maxOccurs="unbounded"
dfdl:occursCount="{ *xs:unsignedInt(../fields)* }"
dfdl:occursCountKind="expression">
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:pattern value="[a-zA-Z0-9+=]{0,64}"/>
</xs:restriction>
</xs:simpleType>
</xs:element>
Thx again... after the fact.
Attila
On Fri, Jul 30, 2021 at 12:55 PM Beckerle, Mike <
mbeckerle@owlcyberdefense.com> wrote:
> Model the length field as a string so its characters are perfectly
> preserved.
>
> Where you need to use its value in the number of occurrences, call the
> xs:unsignedInt(...) function on the string value.
>
>
> ------------------------------
> *From:* Attila Horvath <at...@gmail.com>
> *Sent:* Friday, July 30, 2021 12:48 PM
> *To:* users@daffodil.apache.org <us...@daffodil.apache.org>
> *Subject:* Re: variable length CSV records via 'lengthKind' property
>
> Thx to all responses. Got variable length record w/ variable number of
> 'specified' fields working EXCEPT unparsing does not yield "lossless"
> reconstituted data.
>
> Per...
> <xs:element name="fields" type="xs:unsignedInt"/>
>
> "fields" specifies number of fields in record. When "fields" has value
> "1", unparse yields lossless result. However, when "fields" has value "01",
> unparse yields lossful "1" result dropping the leading zero.
>
> Suggestions to resolve? Our solution MUST be lossless.
>
> Thx in advance
>
> Attila
>
> On 2021/07/21 14:01:12, "Beckerle, Mike" <mb...@owlcyberdefense.com>
> wrote:
> > There is an example of doing dfdl:occursCountKind 'expression' on github
> in the CSV example here:
> >
> >
> https://github.com/DFDLSchemas/CSV/blob/master/src/main/resources/com/tresys/csv/xsd/csvHeaderEnforced.dfdl.xsd
> >
> > Line 75 of this file, it uses this technique to ensure each row has the
> same number of items as there were titles in the initial header row. Your
> case you want a different expression to pick out the exact count from an
> earlier element, but the example may help.
> >
> >
> >
> > ________________________________
> > From: Steve Lawrence <sl...@apache.org>
> > Sent: Wednesday, July 21, 2021 9:52 AM
> > To: users@daffodil.apache.org <us...@daffodil.apache.org>
> > Subject: Re: variable length CSV records via 'lengthKind' property
> >
> > You cannot dynamically set maxOccurs--that has to be either a static
> > number or "unbounded". This is a restriction of XML Schema that DFDL is
> > based off of.
> >
> > But Daffodil does support what you're trying to do . First, you'll want
> > to set maxOccurs="unbounded" (since we don't know how many parameter
> > instances there might be). Bbut then we can use the
> > dfdl:occursCountKind="expression" and dfdl:occursCount properties to
> > evaluate an expression at parse time to set the number of occurrences to
> > the value of the third field. For example:
> >
> > ...
> > <xs:element name="field3" type="xs:int" ... />
> > <xs:element name="parameters" type="..." maxOccurs="unbounded"
> > dfdl:occursCountKind="expression"
> > dfdl:occursCount="{ ../field3 }" ... />
> > ...
> >
> > So we parse field3 to an integer and then use that value in an
> > expression to determine the number of occurrences of the parameters
> array.
> >
> >
> > On 7/21/21 8:04 AM, Horvath, Attila J CTR (USA) wrote:
> > > ALCON - see attached PDF version of this message
> > >
> > > I have a Character Separated Values [CSV] ASCII input file where:
> > >
> > > - fields are ASCII STX character [0x02] separated
> > >
> > > - variable number of fields per below
> > >
> > > - records are ASCII DC4 character [0x14] terminated
> > >
> > > - file is ASCII EOT character [0x04] terminated
> > >
> > > In following sample excerpt, highlighted in YELLOW is last record of
> data file.
> > >
> > > 3rd field [31 30] specifies 10 fields to follow each STX [0x02]
> delimited,
> > >
> > > followed by record and file terminators [0x14 0x04] respectively...
> > >
> > > Is it possible to read the 3rd field ['10'], save it via
> [*_dfdl:lengthKind_*
> > > and/or *_dfdl:defineVariable_*] as "NUM_FIELDS" and pass that value to
> > > 'maxOccurs' attribute on per record basis?
> > >
> > > EG:...
> > >
> > > <xs:element name="parameters" maxOccurs=NUM_FIELDS minOccurs="1">
> > >
> > > ...
> > >
> > > </xs:element>
> > >
> > > Thx in advance
> > >
> > > Attila
> > >
> >
> >
>
Re: variable length CSV records via 'lengthKind' property
Posted by "Beckerle, Mike" <mb...@owlcyberdefense.com>.
Model the length field as a string so its characters are perfectly preserved.
Where you need to use its value in the number of occurrences, call the xs:unsignedInt(...) function on the string value.
________________________________
From: Attila Horvath <at...@gmail.com>
Sent: Friday, July 30, 2021 12:48 PM
To: users@daffodil.apache.org <us...@daffodil.apache.org>
Subject: Re: variable length CSV records via 'lengthKind' property
Thx to all responses. Got variable length record w/ variable number of 'specified' fields working EXCEPT unparsing does not yield "lossless" reconstituted data.
Per...
<xs:element name="fields" type="xs:unsignedInt"/>
"fields" specifies number of fields in record. When "fields" has value "1", unparse yields lossless result. However, when "fields" has value "01", unparse yields lossful "1" result dropping the leading zero.
Suggestions to resolve? Our solution MUST be lossless.
Thx in advance
Attila
On 2021/07/21 14:01:12, "Beckerle, Mike" <mb...@owlcyberdefense.com> wrote:
> There is an example of doing dfdl:occursCountKind 'expression' on github in the CSV example here:
>
> https://github.com/DFDLSchemas/CSV/blob/master/src/main/resources/com/tresys/csv/xsd/csvHeaderEnforced.dfdl.xsd
>
> Line 75 of this file, it uses this technique to ensure each row has the same number of items as there were titles in the initial header row. Your case you want a different expression to pick out the exact count from an earlier element, but the example may help.
>
>
>
> ________________________________
> From: Steve Lawrence <sl...@apache.org>
> Sent: Wednesday, July 21, 2021 9:52 AM
> To: users@daffodil.apache.org <us...@daffodil.apache.org>
> Subject: Re: variable length CSV records via 'lengthKind' property
>
> You cannot dynamically set maxOccurs--that has to be either a static
> number or "unbounded". This is a restriction of XML Schema that DFDL is
> based off of.
>
> But Daffodil does support what you're trying to do . First, you'll want
> to set maxOccurs="unbounded" (since we don't know how many parameter
> instances there might be). Bbut then we can use the
> dfdl:occursCountKind="expression" and dfdl:occursCount properties to
> evaluate an expression at parse time to set the number of occurrences to
> the value of the third field. For example:
>
> ...
> <xs:element name="field3" type="xs:int" ... />
> <xs:element name="parameters" type="..." maxOccurs="unbounded"
> dfdl:occursCountKind="expression"
> dfdl:occursCount="{ ../field3 }" ... />
> ...
>
> So we parse field3 to an integer and then use that value in an
> expression to determine the number of occurrences of the parameters array.
>
>
> On 7/21/21 8:04 AM, Horvath, Attila J CTR (USA) wrote:
> > ALCON - see attached PDF version of this message
> >
> > I have a Character Separated Values [CSV] ASCII input file where:
> >
> > - fields are ASCII STX character [0x02] separated
> >
> > - variable number of fields per below
> >
> > - records are ASCII DC4 character [0x14] terminated
> >
> > - file is ASCII EOT character [0x04] terminated
> >
> > In following sample excerpt, highlighted in YELLOW is last record of data file.
> >
> > 3rd field [31 30] specifies 10 fields to follow each STX [0x02] delimited,
> >
> > followed by record and file terminators [0x14 0x04] respectively...
> >
> > Is it possible to read the 3rd field ['10'], save it via [*_dfdl:lengthKind_*
> > and/or *_dfdl:defineVariable_*] as "NUM_FIELDS" and pass that value to
> > 'maxOccurs' attribute on per record basis?
> >
> > EG:...
> >
> > <xs:element name="parameters" maxOccurs=NUM_FIELDS minOccurs="1">
> >
> > ...
> >
> > </xs:element>
> >
> > Thx in advance
> >
> > Attila
> >
>
>
Re: variable length CSV records via 'lengthKind' property
Posted by Attila Horvath <at...@gmail.com>.
Thx to all responses. Got variable length record w/ variable number of 'specified' fields working EXCEPT unparsing does not yield "lossless" reconstituted data.
Per...
<xs:element name="fields" type="xs:unsignedInt"/>
"fields" specifies number of fields in record. When "fields" has value "1", unparse yields lossless result. However, when "fields" has value "01", unparse yields lossful "1" result dropping the leading zero.
Suggestions to resolve? Our solution MUST be lossless.
Thx in advance
Attila
On 2021/07/21 14:01:12, "Beckerle, Mike" <mb...@owlcyberdefense.com> wrote:
> There is an example of doing dfdl:occursCountKind 'expression' on github in the CSV example here:
>
> https://github.com/DFDLSchemas/CSV/blob/master/src/main/resources/com/tresys/csv/xsd/csvHeaderEnforced.dfdl.xsd
>
> Line 75 of this file, it uses this technique to ensure each row has the same number of items as there were titles in the initial header row. Your case you want a different expression to pick out the exact count from an earlier element, but the example may help.
>
>
>
> ________________________________
> From: Steve Lawrence <sl...@apache.org>
> Sent: Wednesday, July 21, 2021 9:52 AM
> To: users@daffodil.apache.org <us...@daffodil.apache.org>
> Subject: Re: variable length CSV records via 'lengthKind' property
>
> You cannot dynamically set maxOccurs--that has to be either a static
> number or "unbounded". This is a restriction of XML Schema that DFDL is
> based off of.
>
> But Daffodil does support what you're trying to do . First, you'll want
> to set maxOccurs="unbounded" (since we don't know how many parameter
> instances there might be). Bbut then we can use the
> dfdl:occursCountKind="expression" and dfdl:occursCount properties to
> evaluate an expression at parse time to set the number of occurrences to
> the value of the third field. For example:
>
> ...
> <xs:element name="field3" type="xs:int" ... />
> <xs:element name="parameters" type="..." maxOccurs="unbounded"
> dfdl:occursCountKind="expression"
> dfdl:occursCount="{ ../field3 }" ... />
> ...
>
> So we parse field3 to an integer and then use that value in an
> expression to determine the number of occurrences of the parameters array.
>
>
> On 7/21/21 8:04 AM, Horvath, Attila J CTR (USA) wrote:
> > ALCON - see attached PDF version of this message
> >
> > I have a Character Separated Values [CSV] ASCII input file where:
> >
> > - fields are ASCII STX character [0x02] separated
> >
> > - variable number of fields per below
> >
> > - records are ASCII DC4 character [0x14] terminated
> >
> > - file is ASCII EOT character [0x04] terminated
> >
> > In following sample excerpt, highlighted in YELLOW is last record of data file.
> >
> > 3rd field [31 30] specifies 10 fields to follow each STX [0x02] delimited,
> >
> > followed by record and file terminators [0x14 0x04] respectively...
> >
> > Is it possible to read the 3rd field ['10'], save it via [*_dfdl:lengthKind_*
> > and/or *_dfdl:defineVariable_*] as "NUM_FIELDS" and pass that value to
> > 'maxOccurs' attribute on per record basis?
> >
> > EG:...
> >
> > <xs:element name="parameters" maxOccurs=NUM_FIELDS minOccurs="1">
> >
> > ...
> >
> > </xs:element>
> >
> > Thx in advance
> >
> > Attila
> >
>
>
Re: variable length CSV records via 'lengthKind' property
Posted by "Beckerle, Mike" <mb...@owlcyberdefense.com>.
There is an example of doing dfdl:occursCountKind 'expression' on github in the CSV example here:
https://github.com/DFDLSchemas/CSV/blob/master/src/main/resources/com/tresys/csv/xsd/csvHeaderEnforced.dfdl.xsd
Line 75 of this file, it uses this technique to ensure each row has the same number of items as there were titles in the initial header row. Your case you want a different expression to pick out the exact count from an earlier element, but the example may help.
________________________________
From: Steve Lawrence <sl...@apache.org>
Sent: Wednesday, July 21, 2021 9:52 AM
To: users@daffodil.apache.org <us...@daffodil.apache.org>
Subject: Re: variable length CSV records via 'lengthKind' property
You cannot dynamically set maxOccurs--that has to be either a static
number or "unbounded". This is a restriction of XML Schema that DFDL is
based off of.
But Daffodil does support what you're trying to do . First, you'll want
to set maxOccurs="unbounded" (since we don't know how many parameter
instances there might be). Bbut then we can use the
dfdl:occursCountKind="expression" and dfdl:occursCount properties to
evaluate an expression at parse time to set the number of occurrences to
the value of the third field. For example:
...
<xs:element name="field3" type="xs:int" ... />
<xs:element name="parameters" type="..." maxOccurs="unbounded"
dfdl:occursCountKind="expression"
dfdl:occursCount="{ ../field3 }" ... />
...
So we parse field3 to an integer and then use that value in an
expression to determine the number of occurrences of the parameters array.
On 7/21/21 8:04 AM, Horvath, Attila J CTR (USA) wrote:
> ALCON - see attached PDF version of this message
>
> I have a Character Separated Values [CSV] ASCII input file where:
>
> - fields are ASCII STX character [0x02] separated
>
> - variable number of fields per below
>
> - records are ASCII DC4 character [0x14] terminated
>
> - file is ASCII EOT character [0x04] terminated
>
> In following sample excerpt, highlighted in YELLOW is last record of data file.
>
> 3rd field [31 30] specifies 10 fields to follow each STX [0x02] delimited,
>
> followed by record and file terminators [0x14 0x04] respectively...
>
> Is it possible to read the 3rd field ['10'], save it via [*_dfdl:lengthKind_*
> and/or *_dfdl:defineVariable_*] as "NUM_FIELDS" and pass that value to
> 'maxOccurs' attribute on per record basis?
>
> EG:...
>
> <xs:element name="parameters" maxOccurs=NUM_FIELDS minOccurs="1">
>
> ...
>
> </xs:element>
>
> Thx in advance
>
> Attila
>
Re: variable length CSV records via 'lengthKind' property
Posted by Steve Lawrence <sl...@apache.org>.
You cannot dynamically set maxOccurs--that has to be either a static
number or "unbounded". This is a restriction of XML Schema that DFDL is
based off of.
But Daffodil does support what you're trying to do . First, you'll want
to set maxOccurs="unbounded" (since we don't know how many parameter
instances there might be). Bbut then we can use the
dfdl:occursCountKind="expression" and dfdl:occursCount properties to
evaluate an expression at parse time to set the number of occurrences to
the value of the third field. For example:
...
<xs:element name="field3" type="xs:int" ... />
<xs:element name="parameters" type="..." maxOccurs="unbounded"
dfdl:occursCountKind="expression"
dfdl:occursCount="{ ../field3 }" ... />
...
So we parse field3 to an integer and then use that value in an
expression to determine the number of occurrences of the parameters array.
On 7/21/21 8:04 AM, Horvath, Attila J CTR (USA) wrote:
> ALCON - see attached PDF version of this message
>
> I have a Character Separated Values [CSV] ASCII input file where:
>
> - fields are ASCII STX character [0x02] separated
>
> - variable number of fields per below
>
> - records are ASCII DC4 character [0x14] terminated
>
> - file is ASCII EOT character [0x04] terminated
>
> In following sample excerpt, highlighted in YELLOW is last record of data file.
>
> 3rd field [31 30] specifies 10 fields to follow each STX [0x02] delimited,
>
> followed by record and file terminators [0x14 0x04] respectively...
>
> Is it possible to read the 3rd field ['10'], save it via [*_dfdl:lengthKind_*
> and/or *_dfdl:defineVariable_*] as "NUM_FIELDS" and pass that value to
> 'maxOccurs' attribute on per record basis?
>
> EG:...
>
> <xs:element name="parameters" maxOccurs=NUM_FIELDS minOccurs="1">
>
> ...
>
> </xs:element>
>
> Thx in advance
>
> Attila
>