Question

How can I map XML element attributes?

R
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I am trying to flatten an xml file which contains the following Elements

 

 

 <?xml version="1.0" encoding="UTF-8"?> <elements total="877" num="877"> <element id="242698" v="2" pv="1" x="1109133" y="6970266" geom="POINT (9.9699121998145532 52.9278245931941953)" priority="0" type="99" approved="1" current="1" latest="1" date="2014-07-08 13:15:52" user="10" user_token="Friedrich"> <types> <type id="562"/> </types> <periods> <period id="32"/> </periods> <events> <event type="1" begin_prefix="~" begin_year="1790" end_prefix="~" end_year="1790"/> </events> <aspects> <a id="1" l="de" v="Alter Schafstall"/> <a id="2" p="5" code="6"/> <a id="3" p="10" code="3"/> <a id="39" l="de" v="Zehn "/> <a id="41" l="de" v="Zwischen"/> <a id="57" l="de" v="etwa 40m"/> </aspects> <relations/> <media> <medium id="79236"/> <medium id="79237"/> </media> </element> </elements>
 

 

It party works when I define the "elements to match" as <element> but the attributes in the <a> tag are not being flattened. They get translated into the "xml_fragments" field which contains xml-style code. I don´t understand where this "xml_fragments" comes from and would like simply map the attributes into their own fields like "a.id" "a.l" or "a.v".

 

 

Could anyone explain to me what is going on here?

8 replies

takashi
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Hi,

 

 

Since there are multiple <a> elements under an <element>, those attributes will be flattened as structured list, like this.

 

aspect.a{}.code

 

aspect.a{}.id

 

aspect.a{}.l

 

aspect.a{}.p

 

aspect.a{}.v

 

 

Takashi
R
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This isn´t happening though. FME creates the field "xml_fragment" and basically inputs the whole xml file including the structural elements <, > / etc. I really don´t understand why this is happening! Any help would be appreciated.

 

 

takashi
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If you specify "element" to Elements to Match parameter, "a" and its attributes will be stored in structured list as I mentioned in my previous post.

 

As long as seeing your image, I guess that you've specified "a" to Elements to Match.

 

 

Anyway, when using Feature Paths as configuration type, the XML reader adds "xml_fragment" to the reader feature type by default. This attribute stores an element matched with specified element (i.e. "a" in this case) as an XML document.

 

I think there are no problems, just ignore if you don't need it.

 

If you don't want to extract "xml_fragment" anyhow, consider using xfMap instead of Feature Paths.
R
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Thanks....but in my case then, why is the following list element empty?

 

 

 <a id="1" l="de" v="Alter Schafstall"/> 
 

 

As I understand it,  the element "v" which contains the text "Alter Schafstall" should be contained within the list a.v

 

 

Am I correct?

 

 

takashi
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Userlevel 2
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"a.v" is an attribute, is not a list attribute.

 

Yes, "a.v" of the first feature should contain "Alter Schafstall".
takashi
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Connect an Inspector to the reader feature type and run the workspace. You can see how XML elements and attribute values are extracted.
R
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OK...when I define "elements to match" as "a", then I obtain a table with the string "Alter Schaftstall" under element a.v! But when i the "element to match" is defined as element, then I expect aspect.a.v to include the string.  Looking at the XML Document, Element is the parent, and "aspects" and "a" are children and "v" is the attribute. So why can´t I get the string when I define "elements"?

takashi
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Userlevel 2
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Because there are multiple <a> elements in an <elements> element. By default, the XML reader configures list attribute for multiple children which have same tag name.

 

Probably these list attributes occur in the reader feature type when you specify <elements> to Elements to Match.

 

element.aspects.a{}.v

 

element.aspects.a{}.p

 

and so on.

 

 

If this case, you will have to extract elements of the lists in the data flow after reading.

 

See here about lists.

 

http://docs.safe.com/fme/html/FME_Transformers/Default.htm#Categories/lists.htm%3FTocPath%3DFME%20Transformers%7CLists%7C_____0

 

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