Same Result when Outputting Data Using Double Foreach Loop

Question

I need to set a string into something like this

<Student>
    <StudentID></StudentID>
    <FirstName></FirstName>
    <Fees>
         <Fee>
             <FeeID></FeeID>
         </Fee>
    </Fees>
</Student>
<Student>
    <StudentID></StudentID>
    <FirstName></FirstName>
    <Fees>
         <Fee>
             <FeeID></FeeID>
         </Fee>
    </Fees>
</Student>
... and so on

My code

string strFeeData = ""; // XML Content for Fees
string strStuData = ""; // XML Content for Students with Fees

foreach (var studentData in sorted)
{
    foreach(Fee feeData in studentData.Fees)
    {
        strFeeData = strFeeData + "<Fee>\n\t<FeeID>" + feeData.FeeID + "</FeeID>\n\t<FeeName>" + feeData.FeeName + "</FeeName>\n\t<Amount>" + feeData.Amount + "</Amount>\n\t<DueDate>" + feeData.DueDate + "</DueDate>\n</Fee>\n";
    }
    strStuData = strStuData + "<Student>\n\t<StudentID>" + studentData.StudentID + "</StudentID>\n<FirstName>" + studentData.FirstName + "</FirstName>\n<LastName>" + studentData.LastName + "</LastName>\n<Grade>" + studentData.Grade + "</Grade>\n<Fees>\n\t" + strFeeData + "</Fees></Student>\n";
}

I got this part outputted correctly

<Student>
    <StudentID>1</StudentID>
    <FirstName>David</FirstName>
...
<Student>
    <StudentID>2</StudentID>
    <FirstName>John</FirstName>

But for Fees

<Fees>
     <Fee>
         <FeeID>12</FeeID>
....
<Fees>
     <Fee>
         <FeeID>12</FeeID>

I got the same Fees for every students.

What is wrong with my double foreach loop?

(I already checked sorted's Fee has different values, the problem must be at the double foreach loop)

Thanks

Why are you creating XML by hand? It's an incredibly error-prone approach. Use one of the many XML APIs available in .NET - ideally LINQ to XML. — Jon Skeet
– Jon Skeet, Commented Mar 13, 2013 at 8:03

MarcinJuraszek · Accepted Answer · 2013-03-13 08:08:25Z

2

Initialize strFeeData with empty string within outer loop:

foreach (var studentData in sorted)
{
    strFeeData = "";

    foreach(Fee feeData in studentData.Fees)
    {
        strFeeData = strFeeData + "<Fee>\n\t<FeeID>" + feeData.FeeID + "</FeeID>\n\t<FeeName>" + feeData.FeeName + "</FeeName>\n\t<Amount>" + feeData.Amount + "</Amount>\n\t<DueDate>" + feeData.DueDate + "</DueDate>\n</Fee>\n";
    }
    strStuData = strStuData + "<Student>\n\t<StudentID>" + studentData.StudentID + "</StudentID>\n<FirstName>" + studentData.FirstName + "</FirstName>\n<LastName>" + studentData.LastName + "</LastName>\n<Grade>" + studentData.Grade + "</Grade>\n<Fees>\n\t" + strFeeData + "</Fees></Student>\n";
}

However, it's really bad idea to create XML using string concatenation! You should read about Serialization or LINQ to XML!

LINQ to XML version

var xml = sorted.Select(s => new XElement("Student"
                                 new XElement("StudentID", s.StudentID),
                                 new XElement("FirstName", s.FirstName),
                                 new XElement("LastName", s.LastName),
                                 new XElement("Fees",
                                    s.Fees.Select(f => new XElement("Fee",
                                                           new XElement("FeeID", f.FeeID))).ToArray())));

edited Mar 13, 2013 at 8:08

answered Mar 13, 2013 at 8:02

MarcinJuraszek

126k15 gold badges200 silver badges267 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

user1618180 Over a year ago

with the strFeeData = ""; it made it worse :p now it shows only 1 Student with all the fees

user1618180 Over a year ago

With the LINQ to XML version, once I have the var xml, do I just textwriter(xml); ? or what to do with it?

user1618180 Over a year ago

I ToString(); it and tried to console.writeline, it ended up showing "System.Linq.Enumerable+WhereSelectEnumerableIterator2[<>f__AnonymousType06[Sys tem.Int32,System.String,System.String,System.String,System.Double,System.Linq.IO rderedEnumerable`1[StudentList.RServiceReference.Fee]],System.Xml.Linq.XElement]"

MarcinJuraszek Over a year ago

The main problem here is that you don't have a root element at all within your XML! You should create node like <Students> with all students (var students = new XElement("Students", xml);), and then call students.ToString()

Pranay Rana · Accepted Answer · 2013-03-13 13:18:00Z

2

why dont you try out like this ,You can always use XmlSerializer to transform a list of C# objects to XML document.

public string ToXML()
    {
        var stringwriter = new System.IO.StringWriter();
        var serializer = new XmlSerializer(this.GetType());
        serializer.Serialize(stringwriter, this);
        return stringwriter.ToString();
    }

this seializ your class to xml string

Also check this : Convert a C# object to XML?

Linq To XML way

XElement _customers = new XElement("Students",
                       from c in objCust
                       orderby c.CustID //descending 
                        select new XElement("Student",
                            new XElement("name", c.StudentID),
                            new XElement("ID", c.FirstName),
                            new XElement("phone", c.LastName),
                            new XElement("Fees", (from x in x.Fees
                                                  orderby x.FeeID//descending 
                            select new XElement("FeeID",x.FeesId)) 
                        ))

                  );

edited Mar 13, 2013 at 13:18

answered Mar 13, 2013 at 8:04

Pranay Rana

177k37 gold badges244 silver badges267 bronze badges

1 Comment

Pranay Rana Over a year ago

@user1618180 - check the serialization in C# on google and also check the link given you will get idea

Collectives™ on Stack Overflow

Same Result when Outputting Data Using Double Foreach Loop

2 Answers 2

4 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

4 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related