XSLT sum by lookup value from another file - xslt

Question

I want to get the total of a specific student from following 2 XML files:
--- File: mark.xml ----
<marks>
<mark type="HD">10</mark>
<mark type="D">8</mark>
<mark type="C">5</mark>
</marks>
--- File: studentRecord.xml ---
<students>
<student id="1234">
<grade>HD</grade>
</student>
<student id="1234">
<grade>C</grade>
</student>
<student id="1111">
<grade>D</grade>
</student>
</students>
How can I get the total mark of the student having id 1234? it should be 15.

Answer 1

Here is a short and easy XSLT solution (actually it is just XPath):
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:my="my:my">
<xsl:output method="text"/>
<my:MarkValues>
<marks>
<mark type="HD">10</mark>
<mark type="D">8</mark>
<mark type="C">5</mark>
</marks>
</my:MarkValues>
<xsl:template match="/*">
<xsl:value-of select=
"sum(document('')/*
/my:MarkValues/*/*
[#type = current()/*
[#id='1234']/grade
]
)"/>
</xsl:template>
</xsl:stylesheet>
when this transformation is applied to the provided XML document (named "studentRecord.xml") :
<students>
<student id="1234">
<grade>HD</grade>
</student>
<student id="1234">
<grade>C</grade>
</student>
<student id="1111">
<grade>D</grade>
</student>
</students>
the wanted answer is produced:
15
If you want to keep the marks values in a separate file (not embedded into the XSLT stylesheet as above), the XPath expression should be slightly changed (just the argument to the document() function:
sum(document('mark.xml')/*/*
[#type = current()/*
[#id='1234']/grade
]
)
Explanation:
Using the XSLT document() function.
Using the XSLT current() function.
Using the XPath sum() function.

Answer 2

In the following transform I build first a variable with the gathered values and then XPath sum() function is used to get the result. It's not as elegant and smart as #Dimitre approach but I'd like to post anyway :)
XSLT 2.0 tested under Saxon-HE 9.2.1.1J
<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output omit-xml-declaration="yes" indent="yes"/>
<xsl:variable name="lookup" select="document('lookup.xml')/marks"/>
<xsl:template match="students">
<xsl:variable name="values">
<values>
<xsl:for-each select="student[#id='1234']">
<value><xsl:value-of select="$lookup/mark[#type=current()/grade]"/></value>
</xsl:for-each>
</values>
</xsl:variable>
<xsl:value-of select="sum($values//value)"/>
</xsl:template>
</xsl:stylesheet>
The result applied on the input data provided in the question is just the sum:
15

Answer 3

Try this C# code:
var studenst = XElement.Load("studentRecord.xml");
var marks= XElement.Load("marks.xml");
Dictionary<string, int> marksDic = new Dictionary<string, int>();
foreach (XElement m in marks.Descendants())
{
if (m.Attribute("type") != null)
marksDic.Add(m.Attribute("type").Value, int.Parse(m.Value));
}
foreach (XElement s in studenst.Descendants().Where(x=>(x.Attribute("id") !=null ?int.Parse(x.Attribute("id").Value):0)==id))
{
Console.WriteLine(marksDic.Where(x => x.Key == s.Value)
.Select(x => x.Value).Single());
}
}