Create comma separated list from list of objects

Question

I have list of objects type Person. This class has many properties and I need them all in a comma separated list so I can use it later for Csv file.

I've managed this with foreach and adding each property, separating it with commas manual, etc.

const string commaSeparator = ",";
foreach (var item in individualsInformation)
{
    csv.AppendLine(item.ReferenceNumber + commaSeparator + item.FirstName + commaSeparator +
                   item.Surname + commaSeparator + item.MiddleName + commaSeparator +
                   item.Address1 + commaSeparator + item.Address2 + commaSeparator + 
                   item.Address3 + commaSeparator + item.Address4 + commaSeparator + 
                   item.City + commaSeparator + item.PostalCode + commaSeparator +
                   item.Country + commaSeparator + item.DateOfBirth.ToString() + commaSeparator +
                   item.ID + commaSeparator + item.Gender + commaSeparator +
                   item.Component + commaSeparator + item.NationalID + commaSeparator + 
                   item.SubSystemID + commaSeparator + item.System);
}

Then I've realized that there is much efficient way, by using string.Join

This does not work of course:

string joined = string.Join(",", listOfPersons);

And if I go by selecting property like this:

string joined = string.Join(",", listOfPersons(x => x.Id);

I get comma separated list only for that property of course.

Is there some more efficient way for getting each property separated by comma?

Stop trying to reinvent the wheel. Check the answer [here](http://stackoverflow.com/a/25684175/1641172) — , Apr 04 '16 at 08:48
Your current approach isn't all bad and the only way to have full control on everything. — H H, Apr 04 '16 at 08:49

score 18 · Accepted Answer · answered Apr 05 '16 at 08:45

I would avoid reflection if possible.

You can achieve it with compile time safety and readable code easily:

IEnumerable<string> personTexts = listOfPersons
    .Select(p => String.Join(",", p.ReferenceNumber, p.FirstName, p.Surname, ...));
string joined = String.Join(Environment.NewLine, personTexts);

You have full control over which property should be used and in which order.

score 7 · Answer 2 · answered Apr 04 '16 at 08:46

7

Reflection is (sometimes) your friend:

var props = item.GetType().GetProperties(BindingFlags.Public | BindingFlags.Instance); // todo: cache & filter not-needed props)

var itemStr = string.Join(", ", 
                     props.Select(p => p.GetValue(item, null)?.ToString())
                          .ToArray());

answered Apr 04 '16 at 08:46

pwas

3,225
18
40

Reflection totally helped. Thanks! :) @nopeflow – nemo_87 Apr 04 '16 at 08:50

score 4 · Answer 3 · edited Apr 05 '16 at 08:38

Overrride the ToString-Method for your Person-Class

public class Person
{
    //properties...

    public override string ToString()
    {
        return string.Join(",",
            this.ReferenceNumber,
            this.FirstName,
            this.Surname,
            this.MiddleName,
            this.Address1,
            this.Address2,
            this.Address3,
            this.Address4,
            this.City,
            this.PostalCode,
            this.Country,
            this.DateOfBirth.ToString(),
            this.ID,
            this.Gender,
            this.Component,
            this.NationalID,
            this.SubSystemID,
            this.System);
    }
}

so you can use Person.ToString() for csv-generation. Unlike the reflection approach you can easy

maintain the order
handle each type different (BirthDate.ToString("d"), Price.ToString("F2"))
skip values you don't need e.g. System.Collections.Generic.List1[System.String]
change values to your requirements (HasChildren ? "Yes" : "No")

score 0 · Answer 4 · answered Nov 20 '17 at 12:27

Using Reflection where T : class

var valueLines =reportData.Select(row => string.Join(",", header.Split(',').Select(a => row.GetType().GetProperty(a).GetValue(row, null))));

eg

private MemoryStream GenerateExcelStream(List<T> reportData)
    {
        var lines = new List<string>();
        var header = "";
        var attFilter = new NoDisplayInReportAttribute();
        PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(typeof(T));
        foreach (PropertyDescriptor prop in properties)
            if (!prop.Attributes.Matches(attFilter))
                header += prop.Name + ",";
        header = header.Substring(0, header.Length - 1);
        lines.Add(header);
        var valueLines =reportData.Select(row => string.Join(",", header.Split(',').Select(a => row.GetType().GetProperty(a).GetValue(row, null))));
        lines.AddRange(valueLines);
        MemoryStream memoryStream = new MemoryStream();
        TextWriter tw = new StreamWriter(memoryStream);
        lines.ForEach(x => tw.WriteLine(x));
        tw.Flush();
        return memoryStream;
    }

Create comma separated list from list of objects

4 Answers4

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