SharePoint: Cannot open log for source. You may not have write access.

April 21st, 2012 No comments

    In our SharePoint applications we actively use writing into Application Event Log. After adding a new Windows 2008 Server R2 machine to our SP 2010 farm, we was getting the exception “System.ComponentModel.Win32Exception: Access is denied” with the description “Cannot open log for source {*}. You may not have write access.” Apparently, the given error is caused by writing to log when it’s called under an ordinary user with limited rights, who, however, can view web pages. I tried to provide Authenticated Users group with Full Control to the [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\eventlog] registry key, with no success though.

The workaround is add or modify the magic CustomSD value under the registry key [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\eventlog\Application]. So,

  1. Open Registry Editor (click Start, then Run, then type regedit and click Ok);
  2. Locate the [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\eventlog\Application] key in the registry tree;
  3. If the CustomSD value doesn’t exist, create it (right click on Application key, then click New -> String Value and set CustomSD name). Then set value data to O:BAG:SYD:(A;;0x3;;;AU) (right click on CustomSD, then click Modify, type the O:BAG:SYD:(A;;0x3;;;AU) and click Ok). The result should look as shown on the picture below:
    Create CustomSD Value
  4. If the CustomSD value already exists, append (A;;0x3;;;AU) to the value data (right click on CustomSD, then click Modify, type the (A;;0x3;;;AU) at the end of value data and click Ok). After appending, the resultant value data would be similar to:

    O:BAG:SYD:(D;;0xf0007;;;AN)(D;;0xf0007;;;BG)(A;;0x f0007;;;SY)(A;;0x7;;;BA)(A;;0x7;;;SO)(A;;0x3;;;IU)(A;;0x3;;;SU)(A;;0x3;;;S-1-5-3)(A;;0x3;;;AU)

The CustomSD registry value describes which accounts have the read/write/clear permissions to Application Event Log. The format of the value data corresponds to Security Descriptor Definition Language (SDDL), so (A;;0x3;;;AU) consists of

  • A – SDDL_ACCESS_ALLOWED or ACCESS_ALLOWED_ACE_TYPE, one of ACE types;
  • 0x3 – ELF_LOGFILE_WRITE (0x2) & ELF_LOGFILE_READ (0x1), the access rights to the EventLog;
  • AU – Authenticated Users group;

It looks funny that direct giving permissions for Authenticated Users group haven’t had effect, while the EventLog‘s security is controlled by the CustomSD registry value.

Update: If a web application supports anonymous access, you’d better replace AU in (A;;0x3;;;AU) with WD, where WD is Everyone or a group that includes all users. So, the final version in this case is (A;;0x3;;;WD).

Related posts:

SharePoint: Working with BDC Secondary Fields

April 17th, 2012 No comments

    As you probably know, in SharePoint 2010 Business Data Connectivity replaced Business Data Catalog of SharePoint 2007. Some changes affects how Business Data Columns are presented in a list’s schema. In SP 2007 a declaration of a Business Data Column in a schema.xml may look like the following:

<Field Type="BusinessData" DisplayName="Product"
Required="FALSE" ID="{bc203358-6113-470f-9b08-f6100cc034f2}"
StaticName="Product" BaseRenderingType="Text" Name="Product"
SystemInstance="ExternalProductDB_Instance" Entity="Products"
BdcField="Name" Profile="" HasActions="False"
RelatedField="Products_ID"
RelatedFieldBDCField="" RelatedFieldWssStaticName="Products_ID"

SecondaryFieldBdcNames="Price:Producer"
SecondaryFieldWssNames="Product_x003a__x0020_Price:Product_x003a__x0020_Producer"
SecondaryFieldsWssStaticNames="Product_x003a__x0020_Price:Product_x003a__x0020_Producer" />

In contrast, in SP 2010 it looks like

<Field Type="BusinessData" DisplayName="Product"
Required="FALSE" ID="{bc203358-6113-470f-9b08-f6100cc034f2}"
StaticName="Product" BaseRenderingType="Text" Name="Product"
SystemInstance="ExternalProductDB_Instance" Entity="Products"
BdcField="Name" Profile="" HasActions="False"
RelatedField="Products_ID"
RelatedFieldBDCField="" RelatedFieldWssStaticName="Products_ID"

SecondaryFieldBdcNames="6%209%20Price%20Producer%204"
SecondaryFieldWssNames="27%2030%20Product%5Fx003a%5F%5Fx0020%5FPrice%20Product%5Fx003a%5F%5Fx0020%5FProducer%206"
SecondaryFieldsWssStaticNames="27%2030%20Product%5Fx003a%5F%5Fx0020%5FPrice%20Product%5Fx003a%5F%5Fx0020%5FProducer%206" />

Undoubtedly, in SP 2010 the secondary fields became practically unreadable. Indeed, the format of secondary fields‘ presentation is revised. Moreover some kind of URL encoding are applied to them. Let’s examine how these secondary fields could look before the URL encoding is applied:

<Field
...
SecondaryFieldBdcNames="6 9 Price Producer 4"
SecondaryFieldWssNames="27 30 Product_x003a__x0020_Price Product_x003a__x0020_Producer 6"
SecondaryFieldsWssStaticNames="27 30 Product_x003a__x0020_Price Product_x003a__x0020_Producer 6" />

Now it’s pretty easy to figure out the new format. Take a look at the SecondaryFieldBdcNames attribute. It contains names of two secondary bdc fields: ‘Price’ and ‘Producer’. 6 is the length of the ‘Price’ name + 1 for a space character right after the name. 9 is the length of the ‘Procuder’ name + 1 for a space character after the name. 4 is the length of the sub-string ‘6 9 ‘ (including spaces), which contains the lengths of the fields’ names. See a picture below:

Format of Secondary Fields

Note that the SecondaryFieldBdcNames, SecondaryFieldWssNames and SecondaryFieldsWssStaticNames have the same format.

We have a lot of code interacting with Business Data Columns, thus we were interested in means allowing easily to decode, encode and parse Secondary Fields attributes. In the Microsoft.SharePoint.dll, there is the internal BdcClientUtil class containing the basic methods to work with Secondary Fields:

internal class BdcClientUtil
{
    ...
    string[] SplitStrings(string combinedEncoded);
    string   CombineStrings(string[] strings);
    ...
}

So, using .Net Reflector I’ve extracted these methods along with several others auxiliary ones and put them into the helper-class called SecondaryFieldNamesHelper. All internal methods and properties were honestly stolen from Microsoft.SharePoint.dll, the public ones were added by me and described below:

  • string Encode(string[] secondaryFieldNames) – accepts an array of field names and returns the string formatted and encoded according to the SharePoint 2010 requirements;
  • string[] Decode(string str) – accepts an encoded string, decodes it and returns a resultant array of field names;
  • bool IsEncodedString(string str) – checks whether a passed string is encoded;
  • string ConvertToSP2010(string str) – converts a SP 2007 colon-separated string of secondary fields into another one formatted and encoded according to the SharePoint 2010 requirements;

Below is the source code of the SecondaryFieldNamesHelper:

SecondaryFieldNamesHelper Sources

using System;
using System.Collections;
using System.Text;
using System.Globalization;
using System.IO;
using System.Web.UI;

namespace Helpers
{
    public static class SecondaryFieldNamesHelper
    {
        #region fields & properties
        private static string[] s_crgstrUrlHexValue = new string[] 
        { 
            "%00", "%01", "%02", "%03", "%04", "%05", "%06", "%07", "%08", "%09", "%0A", "%0B", "%0C", "%0D", "%0E", "%0F", 
            "%10", "%11", "%12", "%13", "%14", "%15", "%16", "%17", "%18", "%19", "%1A", "%1B", "%1C", "%1D", "%1E", "%1F", 
            "%20", "%21", "%22", "%23", "%24", "%25", "%26", "%27", "%28", "%29", "%2A", "%2B", "%2C", "%2D", "%2E", "%2F", 
            "%30", "%31", "%32", "%33", "%34", "%35", "%36", "%37", "%38", "%39", "%3A", "%3B", "%3C", "%3D", "%3E", "%3F", 
            "%40", "%41", "%42", "%43", "%44", "%45", "%46", "%47", "%48", "%49", "%4A", "%4B", "%4C", "%4D", "%4E", "%4F", 
            "%50", "%51", "%52", "%53", "%54", "%55", "%56", "%57", "%58", "%59", "%5A", "%5B", "%5C", "%5D", "%5E", "%5F", 
            "%60", "%61", "%62", "%63", "%64", "%65", "%66", "%67", "%68", "%69", "%6A", "%6B", "%6C", "%6D", "%6E", "%6F", 
            "%70", "%71", "%72", "%73", "%74", "%75", "%76", "%77", "%78", "%79", "%7A", "%7B", "%7C", "%7D", "%7E", "%7F", 
            "%80", "%81", "%82", "%83", "%84", "%85", "%86", "%87", "%88", "%89", "%8A", "%8B", "%8C", "%8D", "%8E", "%8F", 
            "%90", "%91", "%92", "%93", "%94", "%95", "%96", "%97", "%98", "%99", "%9A", "%9B", "%9C", "%9D", "%9E", "%9F", 
            "%A0", "%A1", "%A2", "%A3", "%A4", "%A5", "%A6", "%A7", "%A8", "%A9", "%AA", "%AB", "%AC", "%AD", "%AE", "%AF", 
            "%B0", "%B1", "%B2", "%B3", "%B4", "%B5", "%B6", "%B7", "%B8", "%B9", "%BA", "%BB", "%BC", "%BD", "%BE", "%BF", 
            "%C0", "%C1", "%C2", "%C3", "%C4", "%C5", "%C6", "%C7", "%C8", "%C9", "%CA", "%CB", "%CC", "%CD", "%CE", "%CF", 
            "%D0", "%D1", "%D2", "%D3", "%D4", "%D5", "%D6", "%D7", "%D8", "%D9", "%DA", "%DB", "%DC", "%DD", "%DE", "%DF", 
            "%E0", "%E1", "%E2", "%E3", "%E4", "%E5", "%E6", "%E7", "%E8", "%E9", "%EA", "%EB", "%EC", "%ED", "%EE", "%EF", 
            "%F0", "%F1", "%F2", "%F3", "%F4", "%F5", "%F6", "%F7", "%F8", "%F9", "%FA", "%FB", "%FC", "%FD", "%FE", "%FF"
        };
        #endregion

        #region public methods
        public static bool IsEncodedString(string str)
        {
            if (string.IsNullOrEmpty(str))
                return false;

            bool res = true;
            try
            {
                string[] splittedString = SplitStrings(str);
            }
            catch
            {
                res = false;
            }
            return res;
        }

        public static string Encode(string[] secondaryFieldNames)
        {
            return CombineStrings(secondaryFieldNames);
        }

        public static string[] Decode(string str)
        {
            if(string.IsNullOrEmpty(str))
                return new string[0];
            return SplitStrings(str);
        }

        public static string ConvertToSP2010(string str)
        {
            if (IsEncodedString(str))
                return str;

            string[] fieldNames = str.Split(new string[] { ":" }, StringSplitOptions.RemoveEmptyEntries);
            string encodedVal = CombineStrings(fieldNames);
            return encodedVal;
        }
        #endregion

        #region internal methods
        private static string[] SplitStrings(string combinedEncoded)
        {
            string[] array = null;
            ArrayList list = new ArrayList();
            if ("0" == combinedEncoded)
                return new string[0];
            try
            {
                string str = UrlKeyValueDecode(combinedEncoded);
                string[] strArray2 = str.Split(new char[] { ' ' }, StringSplitOptions.None);
                int result = 0;
                if ((strArray2 == null) || !int.TryParse(strArray2[strArray2.Length - 1], NumberStyles.Integer, 

CultureInfo.InvariantCulture, out result))
                    throw new ArgumentException(string.Empty, "combinedEncoded");
                int num2 = str.LastIndexOf(' ');
                string str2 = str.Substring(result, num2 - result);
                int length = str2.Length;
                int index = 0;
                int startIndex = 0;
                while (startIndex < length)
                {
                    string s = strArray2[index];
                    int num6 = 1;
                    if ((s != null) && (s.Length == 0))
                        list.Add(null);
                    else
                    {
                        if (!int.TryParse(s, NumberStyles.Integer, CultureInfo.InvariantCulture, out num6))
                            throw new ArgumentException(string.Empty, "combinedEncoded");
                        list.Add(str2.Substring(startIndex, num6 - 1));
                    }
                    startIndex += num6;
                    index++;
                }
                array = new string[list.Count];
                list.CopyTo(array);
            }
            catch (Exception exception)
            {
                throw new ArgumentException(string.Empty, "combinedEncoded", exception);
            }
            return array;
        }

        private static string UrlKeyValueDecode(string keyOrValueToDecode)
        {
            if (string.IsNullOrEmpty(keyOrValueToDecode))
                return keyOrValueToDecode;
            return UrlDecodeHelper(keyOrValueToDecode, keyOrValueToDecode.Length, true);
        }

        private static string UrlDecodeHelper(string stringToDecode, int length, bool decodePlus)
        {
            if ((stringToDecode == null) || (stringToDecode.Length == 0))
                return stringToDecode;
            StringBuilder builder = new StringBuilder(length);
            byte[] bytes = null;
            int nIndex = 0;
            while (nIndex < length)
            {
                char ch = stringToDecode[nIndex];
                if (ch < ' ')
                    nIndex++;
                else
                {
                    if (decodePlus && (ch == '+'))
                    {
                        builder.Append(" ");
                        nIndex++;
                        continue;
                    }
                    if (IsHexEscapedChar(stringToDecode, nIndex, length))
                    {
                        if (bytes == null)
                            bytes = new byte[(length - nIndex) / 3];
                        int count = 0;
                        do
                        {
                            int num3 = (FromHexNoCheck(stringToDecode[nIndex + 1]) * 0x10) + FromHexNoCheck(stringToDecode[nIndex + 

2]);
                            bytes[count++] = (byte)num3;
                            nIndex += 3;
                        }
                        while (IsHexEscapedChar(stringToDecode, nIndex, length));
                        builder.Append(Encoding.UTF8.GetChars(bytes, 0, count));
                        continue;
                    }
                    builder.Append(ch);
                    nIndex++;
                }
            }
            if (length < stringToDecode.Length)
                builder.Append(stringToDecode.Substring(length));
            return builder.ToString();
        }

        private static bool IsHexEscapedChar(string str, int nIndex, int nPathLength)
        {
            if ((((nIndex + 2) >= nPathLength) || (str[nIndex] != '%')) || (!IsHexDigit(str[nIndex + 1]) || !IsHexDigit(str[nIndex + 

2])))
                return false;
            if (str[nIndex + 1] == '0')
                return (str[nIndex + 2] != '0');
            return true;
        }

        private static bool IsHexDigit(char digit)
        {
            if ((('0' > digit) || (digit > '9')) && (('a' > digit) || (digit > 'f')))
                return (('A' <= digit) && (digit <= 'F'));
            return true;
        }

        private static int FromHexNoCheck(char digit)
        {
            if (digit <= '9')
                return (digit - '0');
            if (digit <= 'F')
                return ((digit - 'A') + 10);
            return ((digit - 'a') + 10);
        }

        private static string CombineStrings(string[] strings)
        {
            StringBuilder builder = new StringBuilder();
            int index = 0;
            for (int i = 0; i < strings.Length; i++)
            {
                string str = strings[i];
                string str2 = ((str != null) ? ((str.Length + 1)).ToString(CultureInfo.InvariantCulture) : string.Empty) + ' ';
                builder.Insert(index, str2);
                index += str2.Length;
                builder.Append(str + ' ');
            }
            builder.Append(index.ToString(CultureInfo.InvariantCulture));
            return UrlKeyValueEncode(builder.ToString());
        }

        private static string UrlKeyValueEncode(string keyOrValueToEncode)
        {
            if ((keyOrValueToEncode == null) || (keyOrValueToEncode.Length == 0))
                return keyOrValueToEncode;
            StringBuilder sb = new StringBuilder(0xff);
            HtmlTextWriter output = new HtmlTextWriter(new StringWriter(sb, CultureInfo.InvariantCulture));
            UrlKeyValueEncode(keyOrValueToEncode, output);
            return sb.ToString();
        }

        private static void UrlKeyValueEncode(string keyOrValueToEncode, TextWriter output)
        {
            if (((keyOrValueToEncode != null) && (keyOrValueToEncode.Length != 0)) && (output != null))
            {
                bool fUsedNextChar = false;
                int startIndex = 0;
                int length = 0;
                int num3 = keyOrValueToEncode.Length;
                for (int i = 0; i < num3; i++)
                {
                    char ch = keyOrValueToEncode[i];
                    if (((('0' <= ch) && (ch <= '9')) || (('a' <= ch) && (ch <= 'z'))) || (('A' <= ch) && (ch <= 'Z')))
                        length++;
                    else
                    {
                        if (length > 0)
                        {
                            output.Write(keyOrValueToEncode.Substring(startIndex, length));
                            length = 0;
                        }
                        UrlEncodeUnicodeChar(output, keyOrValueToEncode[i], (i < (num3 - 1)) ? keyOrValueToEncode[i + 1] : '\0', out 

fUsedNextChar);
                        if (fUsedNextChar)
                            i++;
                        startIndex = i + 1;
                    }
                }
                if ((startIndex < num3) && (output != null))
                    output.Write(keyOrValueToEncode.Substring(startIndex));
            }
        }

        private static void UrlEncodeUnicodeChar(TextWriter output, char ch, char chNext, out bool fUsedNextChar)
        {
            bool fInvalidUnicode = false;
            UrlEncodeUnicodeChar(output, ch, chNext, ref fInvalidUnicode, out fUsedNextChar);
        }

        private static void UrlEncodeUnicodeChar(TextWriter output, char ch, char chNext, ref bool fInvalidUnicode, out bool 

fUsedNextChar)
        {
            int num = 0xc0;
            int num2 = 0xe0;
            int num3 = 240;
            int num4 = 0x80;
            int num5 = 0xd800;
            int num6 = 0xfc00;
            int num7 = 0x10000;
            fUsedNextChar = false;
            int index = ch;
            if (index <= 0x7f)
                output.Write(s_crgstrUrlHexValue[index]);
            else
            {
                int num8;
                if (index <= 0x7ff)
                {
                    num8 = num | (index >> 6);
                    output.Write(s_crgstrUrlHexValue[num8]);
                    num8 = num4 | (index & 0x3f);
                    output.Write(s_crgstrUrlHexValue[num8]);
                }
                else if ((index & num6) != num5)
                {
                    num8 = num2 | (index >> 12);
                    output.Write(s_crgstrUrlHexValue[num8]);
                    num8 = num4 | ((index & 0xfc0) >> 6);
                    output.Write(s_crgstrUrlHexValue[num8]);
                    num8 = num4 | (index & 0x3f);
                    output.Write(s_crgstrUrlHexValue[num8]);
                }
                else if (chNext != '\0')
                {
                    index = (index & 0x3ff) << 10;
                    fUsedNextChar = true;
                    index |= chNext & 'Ͽ';
                    index += num7;
                    num8 = num3 | (index >> 0x12);
                    output.Write(s_crgstrUrlHexValue[num8]);
                    num8 = num4 | ((index & 0x3f000) >> 12);
                    output.Write(s_crgstrUrlHexValue[num8]);
                    num8 = num4 | ((index & 0xfc0) >> 6);
                    output.Write(s_crgstrUrlHexValue[num8]);
                    num8 = num4 | (index & 0x3f);
                    output.Write(s_crgstrUrlHexValue[num8]);
                }
                else
                    fInvalidUnicode = true;
            }
        }
        #endregion
    }
}

The SecondaryFieldNamesHelper can be used as shown below:

SPBusinessDataField bdcField = ...

string secondaryFieldWssNamesProperty = bdcField.GetProperty("SecondaryFieldWssNames");
string[] secondaryWssFieldNames = SecondaryFieldNamesHelper.Decode(property);

string secondaryFieldBdcNamesProperty = bdcField.GetProperty("SecondaryFieldBdcNames");
string[] secondaryFieldBdcNames = SecondaryFieldNamesHelper.Decode(secondaryFieldBdcNamesProperty);

string sp2010WssStaticNames = 
   SecondaryFieldNamesHelper.ConvertToSP2010("Product_x003a__x0020_Price:Product_x003a__x0020_Producer");

As a .cs file the SecondaryFieldNamesHelper class is available here.

SharePoint: Remove duplicated fields from a Content Type

March 25th, 2012 No comments

    After in-place upgrading one of our SharePoint applications, we had been faced with the fact that some content types comprised duplicated fields. In other words, within the several <ContentType> sections of a list’s schema, we could find the pair <FieldRef> nodes with identical identifiers and names. Schematically, it looked like the following:

<?xml version="1.0" encoding="utf-8"?>
<List Name="SomeList" Title="Some List" BaseType="0" Url="Lists/SomeList" 
           Type="100" Id="a5bba3b3-5b1d-4186-ada7-bbd82b17f76d" ...>
  <MetaData>
    <Views>
       ...
    </Views>

    <Fields>
       ...
    </Fields>

    <ContentTypes>
       ...
       <ContentType ID="0x0100078C8A39971A4532AB9C5EB6DCB388A3" Name="SomeContentType" ...>
        <FieldRefs>
           ...
           <FieldRef Name="SomeField" ID="{b986cd1a-8bd0-4072-93af-5c48571bbf56}" />
           ...
           <FieldRef Name="SomeField2" ID="{6d245d53-63ef-4650-b676-6e4ee66dcda5}" />
           ...           
           <FieldRef Name="SomeField2" ID="{6d245d53-63ef-4650-b676-6e4ee66dcda5}" />
           ...   
           <FieldRef Name="SomeField" ID="{b986cd1a-8bd0-4072-93af-5c48571bbf56}" />
           ...
        </FieldRefs>
       ...    
    </ContentTypes>

    <Forms>
       ...
    </Forms>
   </MetaData>
</List>

The reason of such duplication still isn’t clear for me, but I’ve figured out how to get rid of it 🙂 Below is a simple method for deleting the excess fields from a passed content type:

protected static void RemoveDuplicatedFields(SPContentType spContentType)
{
    bool duplicationFound = false;

    // identify how many times every field encounter
    Dictionary<Guid, int> tmpDir = new Dictionary<Guid, int>();
    foreach (SPFieldLink spFieldLink in spContentType.FieldLinks)
        if (!tmpDir.ContainsKey(spFieldLink.Id))
            tmpDir.Add(spFieldLink.Id, 1);
        else
        {
            tmpDir[spFieldLink.Id]++;
            duplicationFound = true;
        }
   

    if (duplicationFound)
        // remove all excess mentions of fields
        foreach (KeyValuePair<Guid, int> keyValuePair in tmpDir)
        {
            int removeIterationCount = keyValuePair.Value - 1;
            for (int i = 0; i < removeIterationCount; i++)
                spContentType.FieldLinks.Delete(keyValuePair.Key);
        }
}

SharePoint: Code blocks are not allowed in this file

March 23rd, 2012 No comments

    The SharePoint is based on ASP.Net, so all possible ASP.Net errors may easily become apparent in a SharePoint application. The ‘Code blocks are not allowed in this file‘ issue isn’t an exception. To get rid of it we need to enable server side scripts by modifying the web.config file. Specifically we need to locate <PageParserPaths> within web.config and add a proper <PageParserPath> node to it. The following example demonstrates how to allow server side scripts for all pages, which contain the apps virtual folder in their relative paths:

<PageParserPaths>
    <PageParserPath VirtualPath="/apps/*" CompilationMode="Always" 
              AllowServerSideScript="true" IncludeSubFolders="true" />
</PageParserPaths>

After the modification, server side scripts will work for such pages as e.g.

http://myServer/apps/default.aspx
http://myServer/apps/appsubfolder1/MyPage.aspx (*)
http://myServer/apps/appsubfolder2/MyPage.aspx (*)
http://myServer/apps/appsubfolder2/subfolder3/MyPage.aspx (*)
and so on. 

Note that pages urls marked with asterisks (*) are eligible only if IncludeSubFolders is set to true.

To enable server side scripts for certain page, use something like this:

<PageParserPath VirtualPath="/apps/appsubfolder2/subfolder3/MyPage.aspx" 
              CompilationMode="Always" AllowServerSideScript="true" />

C#: Simple Command Line Arguments Parser

March 22nd, 2012 5 comments

    Working with SharePoint applications I very often develop small console applications for adjusting lists, list items, content types and so on. To pass some parameters into those utilities I employ the command line arguments. Then inside applications I deal with an array of arguments – string[] args:

class Program
{
    static void Main(string[] args)
    {
        // get passed parameters from args
    }
}

I usually use the following notation: -paramName paramValue. Here a parameter name with the leading minus sign (‘-‘) is followed by a parameter value. If the presence of value isn’t assumed, only -paramName is used. For example, the following command line

-url "http://dotnetfollower.com" -useElevatedPrivileges

directs an utility to “process the web site http://dotnetfollower.com and use the elevated objects for that”.

To simplify parameters fetching from the args array I’ve implemented an auxiliary class – InputArguments, which parses the arguments and fills a dictionary out with proper key-value pairs. The dictionary allows accessing a parameter value in the way like this: InputArguments[“-url”] or InputArguments[“url”]. The source code of the InputArguments class is listed below:

using System;
using System.Collections.Generic;

namespace Common
{
    public class InputArguments
    {
        #region fields & properties
        public const string DEFAULT_KEY_LEADING_PATTERN = "-";

        protected Dictionary<string, string> _parsedArguments   = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
        protected readonly string            _keyLeadingPattern;

        public string this [string key]
        {
            get { return GetValue(key); }
            set
            {
                if (key != null)
                    _parsedArguments[key] = value;
            }
        }
        public string KeyLeadingPattern
        {
            get { return _keyLeadingPattern; }
        }
        #endregion

        #region public methods
        public InputArguments(string[] args, string keyLeadingPattern)
        {
            _keyLeadingPattern = !string.IsNullOrEmpty(keyLeadingPattern) ? keyLeadingPattern : DEFAULT_KEY_LEADING_PATTERN;

            if (args != null && args.Length > 0)
                Parse(args);
        }
        public InputArguments(string[] args) : this(args, null)
        {
        }

        public bool Contains(string key)
        {
            string adjustedKey;
            return ContainsKey(key, out adjustedKey);
        }

        public virtual string GetPeeledKey(string key)
        {
            return IsKey(key) ? key.Substring(_keyLeadingPattern.Length) : key;
        }
        public virtual string GetDecoratedKey(string key)
        {
            return !IsKey(key) ? (_keyLeadingPattern + key) : key;
        }
        public virtual bool IsKey(string str)
        {
            return str.StartsWith(_keyLeadingPattern);
        }
        #endregion

        #region internal methods
        protected virtual void Parse(string[] args)
        {
            for (int i = 0; i < args.Length; i ++)
            {
                if(args[i] == null) continue;
                
                string key = null;
                string val = null;

                if(IsKey(args[i])) 
                {
                    key = args[i];

                    if(i + 1 < args.Length && !IsKey(args[i + 1]))
                    {
                        val = args[i + 1];
                        i ++;
                    }
                }
                else
                    val = args[i];

                // adjustment
                if (key == null)
                {
                    key = val;
                    val = null;
                }
                _parsedArguments[key] = val;
            }
        }

        protected virtual string GetValue(string key)
        {
            string adjustedKey;
            if(ContainsKey(key, out adjustedKey))
                return _parsedArguments[adjustedKey];

            return null;
        }

        protected virtual bool ContainsKey(string key, out string adjustedKey)
        {
            adjustedKey = key;

            if (_parsedArguments.ContainsKey(key))
                return true;

            if (IsKey(key))
            {
                string peeledKey = GetPeeledKey(key);
                if(_parsedArguments.ContainsKey(peeledKey))
                {
                    adjustedKey = peeledKey;
                    return true;
                }
                return false;
            }

            string decoratedKey = GetDecoratedKey(key);
            if(_parsedArguments.ContainsKey(decoratedKey))
            {
                adjustedKey = decoratedKey;
                return true;
            }
            return false;
        }
        #endregion
    }
}

As you can see, the InputArguments stores the parsed parameters and theirs values in the _parsedArguments dictionary, which is accessible through the special indexer. Pay attention to the ContainsKey methods, which attempts different variations (with or without leading symbols) of parameter name in case the passed name isn’t presented among the stored arguments. So, passing the

-url "http://dotnetfollower.com" -useElevatedPrivileges

arguments into an application, the InputArguments can be used as follows:

static void Main(string[] args)
{
    InputArguments arguments = new InputArguments(args);

    Console.WriteLine(arguments["-url"]);
    if (arguments.Contains("useElevatedPrivileges"))
        Console.WriteLine("useElevatedPrivileges is set");
}

The above mentioned command line arguments will be turned into the following key-value pairs:

{["-url", "http://dotnetfollower.com"]}
{["-useElevatedPrivileges", null]}

Below is the more complex command line borrowed from the WSPBuilder and slightly modified to have orphaned values without a foregoing parameter name:

"some orphaned value" -ExpandTypes false -BuildSafeControls true  
-WSPName mySPSolution.wsp  -Outputpath "C:\WSPDeployment\myApp" 
-SolutionId d403bb18-c5f2-4b43-9d55-12b256a6295a 
-SolutionPath "C:\WSPDeployment\myApp" -TraceLevel Verbose 
-DLLReferencePath "C:\WSPDeployment\ReferencedAssemblies"

This arguments will be turned into the following:

{["some orphaned value", null]}
{["-ExpandTypes", "false"]}
{["-BuildSafeControls", "true"]}
{["-WSPName", "mySPSolution.wsp"]}
{["-Outputpath", "C:\WSPDeployment\myApp"]}
{["-SolutionId", "d403bb18-c5f2-4b43-9d55-12b256a6295a"]}
{["-SolutionPath", "C:\WSPDeployment\myApp"]}
{["-TraceLevel", "Verbose"]}
{["-DLLReferencePath", "C:\WSPDeployment\ReferencedAssemblies"]}

Frankly speaking, I don’t use the InputArguments class directly. For every utility I create a derived class to provide an easy access to the values of parameters specific for that particular application. For example, the derived class employing the -url and -useElevatedPrivileges may look like the following:

public class UtilityArguments : InputArguments
{
    public bool UseElevatedPrivileges
    {
        get { return GetBoolValue("-useElevatedPrivileges"); }
    }

    public string Url
    {
        get { return GetValue("url"); }
    }

    public UtilityArguments(string[] args) : base(args)
    {
    }

    protected bool GetBoolValue(string key)
    {
        string adjustedKey;
        if (ContainsKey(key, out adjustedKey))
        {
            bool res;
            bool.TryParse(_parsedArguments[adjustedKey], out res);
            return res;
        }
        return false;
    }
}

It can be used as follows:

static void Main(string[] args)
{
    UtilityArguments arguments = new UtilityArguments(args);

    Console.WriteLine("Url: " + arguments.Url);
    Console.WriteLine("UseElevatedPrivileges: " + arguments.UseElevatedPrivileges);
}

If you prefer using another sign or group of signs before parameter name in command line, use the proper constructor of the InputArguments class

static void Main(string[] args)
{
    InputArguments arguments = new InputArguments(args, "/");
    // ...
}

or

public class MyArguments : InputArguments
{
    // ...
    public MyArguments(string[] args) : base(args, "--")
    {
    }
    // ...
}

Categories: C# Tags: ,