Using string join to use ienumerable Extension

Finally, you can see the string shared by the netizen. join tips, I think of my first child, because of string. the join operation can only be performed on the string comment column, and cannot be performed on a set such as list, able, and iqueryable. Therefore, I have created an extension to facilitate myself, so that join can be used for a set like a string.

 

Usage

IEnumerable source = null;

source.Join();

source.Join("PropertyName",",");

source.Join(separator: "|");

 

Original shard

Under iterateextension. CS

/// <summary>

/// Operations on counter objects, such as collections and counter columns.

/// </summary>

public static class IterateExtension

{

/// <summary>

/// Combine the object attribute columns into a string, and use the attribute name of the object to obtain the attribute value of the object.

/// </summary>

/// <Param name = "Source"> columns can be used as the source. </param>

/// <Param name = "propertyname"> property name of an object </param>

/// <Param name = "separator"> separator string </param>

/// <returns></returns>

public static string Join(this IEnumerable source, string propertyName = null, string separator = ",")

{

    if (source == null)

    {

        return null;

    }

    bool nullProperty = propertyName == null;

    StringBuilder sb = new StringBuilder();

    PropertyDescriptor pi = null;

    Type type = null;

    foreach (object value in source)

    {

        if (value == null)

        {

            continue;

        }

        if (value is string || nullProperty)

        {

// If the value is string or the propertyname is null, it is directly exported.

            sb.Append(value);

        }

        else if (value is DataRow)

        {

            sb.Append(((DataRow)value)[propertyName]);

        }

        else

        {

            Type temp = value.GetType();

            if (type != temp)

            {

                type = temp;

// Use typedescriptor. getproperties (object) to obtain the atomicity of icustomtypedescriptor, which can be customized, for example, datarowviw.

// If typedescriptor. getproperties (type) is used, icustomtypedescriptor is not judged.

                pi = TypeDescriptor.GetProperties(value)[propertyName];

                if (pi == null)

                {

                    throw new InvalidOperationException(string.Format("{0} Property {1} Not Exist.", type, propertyName));

                }

            }

            sb.Append(pi.GetValue(value));

        }

        sb.Append(separator);

    }

    return (separator == null || sb.Length == 0) ? sb.ToString() : sb.ToString(0, sb.Length - separator.Length);

}

}

 

Single-dollar renewal

public class Test

{

    public string P1 { get; set; }

    public int P2 { get; set; }

    public override string ToString()

    {

        return this.P1;

    }

}

[TestMethod()]

public void JoinTest()

{

    IEnumerable source = null;

    //String

    source = new string[] { "A", "B", "C" };

    Assert.AreEqual(source.Join(), "A,B,C");

    Assert.AreEqual(source.Join(separator : "|"), "A|B|C");

    //List + class

    source = new List<Test> { new Test() { P1 = "A", P2 = 1 }, new Test() { P1 = "B", P2 = 2 }, new Test() { P1 = "C", P2 = 3 } };

    Assert.AreEqual(source.Join(), "A,B,C");

    Assert.AreEqual(source.Join("P2"), "1,2,3");

    //DataTable And DataView

    DataTable dt = new DataTable();

    dt.Columns.Add("Col1");

    dt.Columns.Add("Col2");

    dt.Rows.Add("A", 1);

    dt.Rows.Add("B", 2);

    dt.Rows.Add("C", 3);

    Assert.AreEqual(dt.Rows.Join("Col1"), "A,B,C");

    Assert.AreEqual(dt.Rows.Join("Col2"), "1,2,3");

    Assert.AreEqual(dt.DefaultView.Join("Col1"), "A,B,C");

    Assert.AreEqual(dt.DefaultView.Join("Col2"), "1,2,3");

    //IQueryable

    TestDataContext db = new TestDataContext();

    source = (from e in db.Employers

                select e).Take(3);            

    Assert.AreEqual(source.Join("Name"), "A,B,C");

}

 

Limit: Originally in 2008, the method has more than one limit. If it is changed to 2010, it is changed to use the limit parameter.