Reading the file only once for every method call - c#

I am new to object-oriented programming and I am working on a small personal project with some SQL scripts.
I have a scenario where a SQL script calls a static method with a file path as input.
queries = Select Query from Table where Utils.ContainsKeyword(Query, #Path1) AND NOT Utils.ContainsKeyword(Query, #Path2);
I had initially created a static class that does the following:
public static class Utils
{
public static bool ContainsKeyword(string query, string path)
{
var isQueryInFile = false;
var stringFromFile = GetStringFromFile(path);
List<Regex>regexList = GetRegexList(stringFromFile);
if(regexList!= null)
{
isQueryInFile = regexList.Any(pattern => pattern.IsMatch(query));
}
return isQueryInFile;
}
private static string GetStringFromFile(string path)
{
var words = String.Empty;
if(!string.IsNullOrEmpty(path))
{
try
{
using (StreamReader sr = File.OpenText(path))
{
words = sr.ReadToEnd().Replace(Environment.Newline, "");
}
}
catch { return words; }
}
return words;
}
private static List<Regex> GetRegexList(string words)
{
if(string.IsNullOrEmpty(words)) { return null; }
return words.Split(',').Select(w=> new Regex(#"\b" + Regex.Escape(w) + #'\b', RegexOptions.Compiled | RegexOptions.IgnoreCase)).ToList();
}
}
My problem is that I neither want to read from the file every time the ContainsKeyword static method is called nor do I want to create a new RegexList every time. Also, I cannot change the SQL script and I have to send the path to the file as an input parameter for the method call in the SQL script since the path might change in the future.
Is there a way to make sure I only read the contents from the input path only once, store them in a string, and use the string for the match with different input queries?

To read the content only once, saving in memory will probaby be needed. Memory capacity could be an issue.
public Dictionary<string, string> FileContentCache { get; set; } // make sure that gets initialized
public string GetFileContentCache(string path)
{
if (FileContentCache == null) FileContentCache = new Dictionary<string, string>();
if (FileContentCache.ContainsKey(path))
return FileContentCache[path];
var fileData = GetStringFromFile(path);
FileContentCache.Add(path, fileData);
return fileData;
}

Related

OpenXml Excel: throw error in any word after mail address

I read Excel files using OpenXml. all work fine but if the spreadsheet contains one cell that has an address mail and after it a space and another word, such as:
abc#abc.com abc
It throws an exception immediately at the opening of the spreadsheet:
var _doc = SpreadsheetDocument.Open(_filePath, false);
exception:
DocumentFormat.OpenXml.Packaging.OpenXmlPackageException
Additional information:
Invalid Hyperlink: Malformed URI is embedded as a
hyperlink in the document.
There is an open issue on the OpenXml forum related to this problem: Malformed Hyperlink causes exception
In the post they talk about encountering this issue with a malformed "mailto:" hyperlink within a Word document.
They propose a work-around here: Workaround for malformed hyperlink exception
The workaround is essentially a small console application which locates the invalid URL and replaces it with a hard-coded value; here is the code snippet from their sample that does the replacement; you could augment this code to attempt to correct the passed brokenUri:
private static Uri FixUri(string brokenUri)
{
return new Uri("http://broken-link/");
}
The problem I had was actually with an Excel document (like you) and it had to do with a malformed http URL; I was pleasantly surprised to find that their code worked just fine with my Excel file.
Here is the entire work-around source code, just in case one of these links goes away in the future:
void Main(string[] args)
{
var fileName = #"C:\temp\corrupt.xlsx";
var newFileName = #"c:\temp\Fixed.xlsx";
var newFileInfo = new FileInfo(newFileName);
if (newFileInfo.Exists)
newFileInfo.Delete();
File.Copy(fileName, newFileName);
WordprocessingDocument wDoc;
try
{
using (wDoc = WordprocessingDocument.Open(newFileName, true))
{
ProcessDocument(wDoc);
}
}
catch (OpenXmlPackageException e)
{
e.Dump();
if (e.ToString().Contains("The specified package is not valid."))
{
using (FileStream fs = new FileStream(newFileName, FileMode.OpenOrCreate, FileAccess.ReadWrite))
{
UriFixer.FixInvalidUri(fs, brokenUri => FixUri(brokenUri));
}
}
}
}
private static Uri FixUri(string brokenUri)
{
brokenUri.Dump();
return new Uri("http://broken-link/");
}
private static void ProcessDocument(WordprocessingDocument wDoc)
{
var elementCount = wDoc.MainDocumentPart.Document.Descendants().Count();
Console.WriteLine(elementCount);
}
}
public static class UriFixer
{
public static void FixInvalidUri(Stream fs, Func<string, Uri> invalidUriHandler)
{
XNamespace relNs = "http://schemas.openxmlformats.org/package/2006/relationships";
using (ZipArchive za = new ZipArchive(fs, ZipArchiveMode.Update))
{
foreach (var entry in za.Entries.ToList())
{
if (!entry.Name.EndsWith(".rels"))
continue;
bool replaceEntry = false;
XDocument entryXDoc = null;
using (var entryStream = entry.Open())
{
try
{
entryXDoc = XDocument.Load(entryStream);
if (entryXDoc.Root != null && entryXDoc.Root.Name.Namespace == relNs)
{
var urisToCheck = entryXDoc
.Descendants(relNs + "Relationship")
.Where(r => r.Attribute("TargetMode") != null && (string)r.Attribute("TargetMode") == "External");
foreach (var rel in urisToCheck)
{
var target = (string)rel.Attribute("Target");
if (target != null)
{
try
{
Uri uri = new Uri(target);
}
catch (UriFormatException)
{
Uri newUri = invalidUriHandler(target);
rel.Attribute("Target").Value = newUri.ToString();
replaceEntry = true;
}
}
}
}
}
catch (XmlException)
{
continue;
}
}
if (replaceEntry)
{
var fullName = entry.FullName;
entry.Delete();
var newEntry = za.CreateEntry(fullName);
using (StreamWriter writer = new StreamWriter(newEntry.Open()))
using (XmlWriter xmlWriter = XmlWriter.Create(writer))
{
entryXDoc.WriteTo(xmlWriter);
}
}
}
}
}
The fix by #RMD works great. I've been using it for years. But there is a new fix.
You can see the fix here in the changelog for issue #793
Upgrade OpenXML to 2.12.0.
Right click solution and select Manage NuGet Packages.
Implement the fix
It is helpful to have a unit test. Create an excel file with a bad email address like test#gmail,com. (Note the comma instead of the dot).
Make sure the stream you open and the call to SpreadsheetDocument.Open allows Read AND Write.
You need to implement a RelationshipErrorHandlerFactory and use it in the options when you open. Here is the code I used:
public class UriRelationshipErrorHandler : RelationshipErrorHandler
{
public override string Rewrite(Uri partUri, string id, string uri)
{
return "https://broken-link";
}
}
Then you need to use it when you open the document like this:
var openSettings = new OpenSettings
{
RelationshipErrorHandlerFactory = package =>
{
return new UriRelationshipErrorHandler();
}
};
using var document = SpreadsheetDocument.Open(stream, true, openSettings);
One of the nice things about this solution is that it does not require you to create a temporary "fixed" version of your file and it is far less code.
Unfortunately solution where you have to open file as zip and replace broken hyperlink would not help me.
I just was wondering how it is posible that it works fine when your target framework is 4.0 even if your only installed .Net Framework has version 4.7.2.
I have found out that there is private static field inside System.UriParser that selects version of URI's RFC specification. So it is possible to set it to V2 as it is set for .net 4.0 and lower versions of .Net Framework. Only problem that it is private static readonly.
Maybe someone will want to set it globally for whole application. But I wrote UriQuirksVersionPatcher that will update this version and restore it back in Dispose method. It is obviously not thread-safe but it is acceptable for my purpose.
using System;
using System.Diagnostics;
using System.Reflection;
namespace BarCap.RiskServices.RateSubmissions.Utility
{
#if (NET20 || NET35 || NET40)
public class UriQuirksVersionPatcher : IDisposable
{
public void Dispose()
{
}
}
#else
public class UriQuirksVersionPatcher : IDisposable
{
private const string _quirksVersionFieldName = "s_QuirksVersion"; //See Source\ndp\fx\src\net\System\_UriSyntax.cs in NexFX sources
private const string _uriQuirksVersionEnumName = "UriQuirksVersion";
/// <code>
/// private enum UriQuirksVersion
/// {
/// V1 = 1, // RFC 1738 - Not supported
/// V2 = 2, // RFC 2396
/// V3 = 3, // RFC 3986, 3987
/// }
/// </code>
private const string _oldQuirksVersion = "V2";
private static readonly Lazy<FieldInfo> _targetFieldInfo;
private static readonly Lazy<int?> _patchValue;
private readonly int _oldValue;
private readonly bool _isEnabled;
static UriQuirksVersionPatcher()
{
var targetType = typeof(UriParser);
_targetFieldInfo = new Lazy<FieldInfo>(() => targetType.GetField(_quirksVersionFieldName, BindingFlags.Static | BindingFlags.NonPublic));
_patchValue = new Lazy<int?>(() => GetUriQuirksVersion(targetType));
}
public UriQuirksVersionPatcher()
{
int? patchValue = _patchValue.Value;
_isEnabled = patchValue.HasValue;
if (!_isEnabled) //Disabled if it failed to get enum value
{
return;
}
int originalValue = QuirksVersion;
_isEnabled = originalValue != patchValue;
if (!_isEnabled) //Disabled if value is proper
{
return;
}
_oldValue = originalValue;
QuirksVersion = patchValue.Value;
}
private int QuirksVersion
{
get
{
return (int)_targetFieldInfo.Value.GetValue(null);
}
set
{
_targetFieldInfo.Value.SetValue(null, value);
}
}
private static int? GetUriQuirksVersion(Type targetType)
{
int? result = null;
try
{
result = (int)targetType.GetNestedType(_uriQuirksVersionEnumName, BindingFlags.Static | BindingFlags.NonPublic)
.GetField(_oldQuirksVersion, BindingFlags.Static | BindingFlags.Public)
.GetValue(null);
}
catch
{
#if DEBUG
Debug.WriteLine("ERROR: Failed to find UriQuirksVersion.V2 enum member.");
throw;
#endif
}
return result;
}
public void Dispose()
{
if (_isEnabled)
{
QuirksVersion = _oldValue;
}
}
}
#endif
}
Usage:
using(new UriQuirksVersionPatcher())
{
using(var document = SpreadsheetDocument.Open(fullPath, false))
{
//.....
}
}
P.S. Later I found that someone already implemented this pathcher: https://github.com/google/google-api-dotnet-client/blob/master/Src/Support/Google.Apis.Core/Util/UriPatcher.cs
I haven't use OpenXml but if there's no specific reason for using it then I highly recommend LinqToExcel from LinqToExcel. Example of code is here:
var sheet = new ExcelQueryFactory("filePath");
var allRows = from r in sheet.Worksheet() select r;
foreach (var r in allRows) {
var cella = r["Header"].ToString();
}

How to take a CSV field and write to columns in SQL

I have the following code which takes a CSV and writes to a console:
using (CsvReader csv = new CsvReader(
new StreamReader("data.csv"), true))
{
// missing fields will not throw an exception,
// but will instead be treated as if there was a null value
csv.MissingFieldAction = MissingFieldAction.ReplaceByNull;
// to replace by "" instead, then use the following action:
//csv.MissingFieldAction = MissingFieldAction.ReplaceByEmpty;
int fieldCount = csv.FieldCount;
string[] headers = csv.GetFieldHeaders();
while (csv.ReadNextRecord())
{
for (int i = 0; i < fieldCount; i++)
Console.Write(string.Format("{0} = {1};",
headers[i],
csv[i] == null ? "MISSING" : csv[i]));
Console.WriteLine();
}
}
The CSV file has 7 headers for which I have 7 columns in my SQL table.
What is the best way to take each csv[i] and write to a row for each column and then move to the next row?
I tried to add the ccsv[i] to a string array but that didn't work.
I also tried the following:
SqlCommand sql = new SqlCommand("INSERT INTO table1 [" + csv[i] + "]", mysqlconnectionstring);
sql.ExecuteNonQuery();
My table (table1) is like this:
name address city zipcode phone fax device
your problem is simple but I will take it one step further and let you know a better way to approach the issue.
when you have a problem to sold, always break it down into parts and apply each part in each own method. For example, in your case:
1 - read from the file
2 - create a sql query
3 - run the query
and you can even add validation to the file (imagine your file does not even have 7 fields in one or more lines...) and the example below it to be taken, only if your file never passes around 500 lines, as if it does normally you should consider to use a SQL statement that takes your file directly in to the database, it's called bulk insert
1 - read from file:
I would use a List<string> to hold the line entries and I always use StreamReader to read from text files.
using (StreamReader sr = File.OpenText(this.CsvPath))
{
while ((line = sr.ReadLine()) != null)
{
splittedLine = line.Split(new string[] { this.Separator }, StringSplitOptions.None);
if (iLine == 0 && this.HasHeader)
// header line
this.Header = splittedLine;
else
this.Lines.Add(splittedLine);
iLine++;
}
}
2 - generate the sql
foreach (var line in this.Lines)
{
string entries = string.Concat("'", string.Join("','", line))
.TrimEnd('\'').TrimEnd(','); // remove last ",'"
this.Query.Add(string.Format(this.LineTemplate, entries));
}
3 - run the query
SqlCommand sql = new SqlCommand(string.Join("", query), mysqlconnectionstring);
sql.ExecuteNonQuery();
having some fun I end up doing the solution and you can download it here, the output is:
The code can be found here. It needs more tweaks but I will left that for others. Solution written in C#, VS 2013.
The ExtractCsvIntoSql class is as follows:
public class ExtractCsvIntoSql
{
private string CsvPath, Separator;
private bool HasHeader;
private List<string[]> Lines;
private List<string> Query;
/// <summary>
/// Header content of the CSV File
/// </summary>
public string[] Header { get; private set; }
/// <summary>
/// Template to be used in each INSERT Query statement
/// </summary>
public string LineTemplate { get; set; }
public ExtractCsvIntoSql(string csvPath, string separator, bool hasHeader = false)
{
this.CsvPath = csvPath;
this.Separator = separator;
this.HasHeader = hasHeader;
this.Lines = new List<string[]>();
// you can also set this
this.LineTemplate = "INSERT INTO [table1] SELECT ({0});";
}
/// <summary>
/// Generates the SQL Query
/// </summary>
/// <returns></returns>
public List<string> Generate()
{
if(this.CsvPath == null)
throw new ArgumentException("CSV Path can't be empty");
// extract csv into object
Extract();
// generate sql query
GenerateQuery();
return this.Query;
}
private void Extract()
{
string line;
string[] splittedLine;
int iLine = 0;
try
{
using (StreamReader sr = File.OpenText(this.CsvPath))
{
while ((line = sr.ReadLine()) != null)
{
splittedLine = line.Split(new string[] { this.Separator }, StringSplitOptions.None);
if (iLine == 0 && this.HasHeader)
// header line
this.Header = splittedLine;
else
this.Lines.Add(splittedLine);
iLine++;
}
}
}
catch (Exception ex)
{
if(ex.InnerException != null)
while (ex.InnerException != null)
ex = ex.InnerException;
throw ex;
}
// Lines will have all rows and each row, the column entry
}
private void GenerateQuery()
{
foreach (var line in this.Lines)
{
string entries = string.Concat("'", string.Join("','", line))
.TrimEnd('\'').TrimEnd(','); // remove last ",'"
this.Query.Add(string.Format(this.LineTemplate, entries));
}
}
}
and you can run it as:
class Program
{
static void Main(string[] args)
{
string file = Ask("What is the CSV file path? (full path)");
string separator = Ask("What is the current separator? (; or ,)");
var extract = new ExtractCsvIntoSql(file, separator);
var sql = extract.Generate();
Output(sql);
}
private static void Output(IEnumerable<string> sql)
{
foreach(var query in sql)
Console.WriteLine(query);
Console.WriteLine("*******************************************");
Console.Write("END ");
Console.ReadLine();
}
private static string Ask(string question)
{
Console.WriteLine("*******************************************");
Console.WriteLine(question);
Console.Write("= ");
return Console.ReadLine();
}
}
Usually i like to be a bit more generic so i'll try to explain a very basic flow i use from time to time:
I don't like the hard coded attitude so even if your code will work it will be dedicated specifically to one type. I prefer i simple reflection, first to understand what DTO is it and then to understand what repository should i use to manipulate it:
For example:
public class ImportProvider
{
private readonly string _path;
private readonly ObjectResolver _objectResolver;
public ImportProvider(string path)
{
_path = path;
_objectResolver = new ObjectResolver();
}
public void Import()
{
var filePaths = Directory.GetFiles(_path, "*.csv");
foreach (var filePath in filePaths)
{
var fileName = Path.GetFileName(filePath);
var className = fileName.Remove(fileName.Length-4);
using (var reader = new CsvFileReader(filePath))
{
var row = new CsvRow();
var repository = (DaoBase)_objectResolver.Resolve("DAL.Repository", className + "Dao");
while (reader.ReadRow(row))
{
var dtoInstance = (DtoBase)_objectResolver.Resolve("DAL.DTO", className + "Dto");
dtoInstance.FillInstance(row.ToArray());
repository.Save(dtoInstance);
}
}
}
}
}
Above is a very basic class responsible importing the data. Nevertheless of how this piece of code parsing CSV files (CsvFileReader), the important part is thata "CsvRow" is a simple List.
Below is the implementation of the ObjectResolver:
public class ObjectResolver
{
private readonly Assembly _myDal;
public ObjectResolver()
{
_myDal = Assembly.Load("DAL");
}
public object Resolve(string nameSpace, string name)
{
var myLoadClass = _myDal.GetType(nameSpace + "." + name);
return Activator.CreateInstance(myLoadClass);
}
}
The idea is to simple follow a naming convetion, in my case is using a "Dto" suffix for reflecting the instances, and "Dao" suffix for reflecting the responsible dao. The full name of the Dto or the Dao can be taken from the csv name or from the header (as you wish)
Next step is filling the Dto, each dto or implements the following simple abstract:
public abstract class DtoBase
{
public abstract void FillInstance(params string[] parameters);
}
Since each Dto "knows" his structure (just like you knew to create an appropriate table in the database), it can easily implement the FillInstanceMethod, here is a simple Dto example:
public class ProductDto : DtoBase
{
public int ProductId { get; set; }
public double Weight { get; set; }
public int FamilyId { get; set; }
public override void FillInstance(params string[] parameters)
{
ProductId = int.Parse(parameters[0]);
Weight = double.Parse(parameters[1]);
FamilyId = int.Parse(parameters[2]);
}
}
After you have your Dto filled with data you should find the appropriate Dao to handle it
which is basically happens in reflection in this line of the Import() method:
var repository = (DaoBase)_objectResolver.Resolve("DAL.Repository", className + "Dao");
In my case the Dao implements an abstract base class - but it's not that relevant to your problem, your DaoBase can be a simple abstract with a single Save() method.
This way you have a dedicated Dao to CRUD your Dto's - each Dao simply knows how to save for its relevant Dto. Below is the corresponding ProductDao to the ProductDto:
public class ProductDao : DaoBase
{
private const string InsertProductQuery = #"SET foreign_key_checks = 0;
Insert into product (productID, weight, familyID)
VALUES (#productId, #weight, #familyId);
SET foreign_key_checks = 1;";
public override void Save(DtoBase dto)
{
var productToSave = dto as ProductDto;
var saveproductCommand = GetDbCommand(InsertProductQuery);
if (productToSave != null)
{
saveproductCommand.Parameters.Add(CreateParameter("#productId", productToSave.ProductId));
saveproductCommand.Parameters.Add(CreateParameter("#weight", productToSave.Weight));
saveproductCommand.Parameters.Add(CreateParameter("#familyId", productToSave.FamilyId));
ExecuteNonQuery(ref saveproductCommand);
}
}
}
Please ignore the CreateParameter() method, since it's an abstraction from the base classs. you can just use a CreateSqlParameter or CreateDataParameter etc.
Just notice, it's a real naive implementation - you can easily remodel it better, depends on your needs.
From the first impression of your questionc I guess you would be having hugely number of records (more than lacs). If yes I would consider the SQL bulk copies an option. If the record would be less go ahead single record. Insert. The reason for you insert not working is u not providing all the columns of the table and also there's some syntax error.

WMI is being too slow

Is there a way to limit the number of entries WMI retrieves with a WQL statement?
I say this because running a query to retrieve all Win32_NTLogEvent instances is taking forever! All I really need are the most recent events (for about a week, or 2000 entries)
Here's a snippet of the code I'm using to get the log data. Other queries such as Win32_Processor are nice and quick.
if (Configuration.OnlyErrorLogs)
{
// If Information logs should be suppressed, only get events where event type is not 3
WMIDataTemp1 = DataRetriever.GetWMIData("Win32_NTLogEvent", "EventType<>3");
}
else
{
WMIDataTemp1 = DataRetriever.GetWMIData("Win32_NTLogEvent");
}
foreach (ManagementObject Object in WMIDataTemp1)
{
this.Log.Add(new Log(Object));
}
And the functions to get WMI data are as follows:
public static ManagementObject[] GetWMIData(string wmiClass) { return GetWMIData(wmiClass, "", "CIMV2"); }
public static ManagementObject[] GetWMIData(string wmiClass, string whereClause) { return GetWMIData(wmiClass, whereClause, "CIMV2"); }
public static ManagementObject[] GetWMIData(string wmiClass, string whereClause, string nameSpace)
{
try
{
// If a where clause has been set, prepare the clause to add to the query string
if (whereClause != "")
{
whereClause = " WHERE " + whereClause;
}
// Create a search query
string query = "SELECT * FROM " + wmiClass + whereClause;
ManagementObjectSearcher wmiSearcher = new ManagementObjectSearcher("root\\" + nameSpace, query);
ManagementObjectCollection matches = wmiSearcher.Get();
// Create an array to hold the matches
ManagementObject[] matchArray = new ManagementObject[matches.Count];
// If matches found, copy to output
if(matches.Count > 0)
{
// Copy the search matches into this array
matches.CopyTo(matchArray, 0);
}
// Return array
return matchArray;
}
catch (Exception e)
{
ErrorDialogue errorReporter = new ErrorDialogue(e);
return null;
}
}
Where each Log gets stored:
public class Log
{
public string Category = "N/A";
public string DateTime = "N/A";
public UInt16 ID = 0;
public string Level = "N/A";
public string Message = "N/A";
public string Source = "N/A";
public Log() { }
public Log(ManagementObject wmiLogEvent)
{
this.GetInfo(wmiLogEvent);
}
public void GetInfo(ManagementObject wmiLogEvent)
{
try
{
this.Category = DataRetriever.GetValue(wmiLogEvent, "CategoryString");
this.DateTime = DataRetriever.GetValue(wmiLogEvent, "TimeGenerated");
this.ID = DataRetriever.GetValueUInt16(wmiLogEvent, "EventIdentifier");
this.Level = DataRetriever.ConvertEventType(DataRetriever.GetValueUInt16(wmiLogEvent, "CategoryString"));
this.Message = DataRetriever.GetValue(wmiLogEvent, "Message");
this.Source = DataRetriever.GetValue(wmiLogEvent, "SourceName");
}
catch (Exception e)
{
ErrorDialogue errorReporter = new ErrorDialogue(e);
}
}
}
One option is to use a WHERE clause to specify the range of the entries you want...
For example you could use TimeGenerated in the WHERE clause to specify a time-based range...
Another option is to set BlockSize accordingly when creating ManagementObjectSearcher.
You could use that to specify that you want 2000 entries per call for example - together with an ORDER BY TimeGenerated DESC this should give a nice result.
Speed is not a strong suit for WMI. It tends to be quite memory intensive. However, the question has been addressed and there are a few things you can do. Check out Why are my queries taking such a long time to complete? from Microsoft TechNet.
Now using the System.Diagnostics.EventLog class as a faster alternative. Much more beneficial to the program compared to WMI.
http://msdn.microsoft.com/en-us/library/system.diagnostics.eventlog.aspx

C# NullReferenceException was unhandled

I am trying to use a CSV parser which I found on the net in my project. The problem is I am getting a null reference exception when I try to convert the string to a Tag and my collection does not get populated. Can anyone assist? Thanks
CSV Parser
private static IEnumerable<string[]> parseCSV(string path)
{
List<string[]> parsedData = new List<string[]>();
try
{
using (StreamReader readFile = new StreamReader(path))
{
string line;
string[] row;
while ((line = readFile.ReadLine()) != null)
{
row = line.Split(',');
parsedData.Add(row);
}
}
}
catch (Exception e)
{
System.Windows.MessageBox.Show(e.Message);
}
return parsedData;
}
Tag Class
public class Tag
{
public Tag(string name, int weight)
{
Name = name;
Weight = weight;
}
public string Name { get; set; }
public int Weight { get; set; }
public static IEnumerable<Tag> CreateTags(IEnumerable<string> words)
{
Dictionary<string, int> tags = new Dictionary<string, int>();
foreach (string word in words)
{
int count = 1;
if (tags.ContainsKey(word))
{
count = tags[word] + 1;
}
tags[word] = count;
}
return tags.Select(kvp => new Tag(kvp.Key, kvp.Value));
}
}
Validate all method arguments before you use them!
It breaks on this line: foreach (string word in words)
Remember that foreach loops work by calling GetEnumerator on the collection iterated over. That is, your foreach loop causes a call to words.GetEnumerator, and this call fails if words is null.
Therefore, validate your argument words by adding a guard at the very start of your CreateTags method:
if (words == null)
{
throw new ArgumentNullException("words");
}
This will help you find the location in your code where null is passed into CreateTags, and you can then continue fixing the calling code.
Suggestion: Avoid null whenever possible.
As a very general rule, try to avoid using null values whenever possible. For example, when your code is dealing with sets and collections of items, you could make sure that it also works correctly with empty collections. In a second step, make sure that you never use null to represent an empty collection; instead, use e.g. LINQ's Enumerable.Empty<TItem>() generator to create an empty collection.
One place where you could start doing this is in the CreateTags method by ensuring that no matter what the inputs are, that method will always return a valid, non-null (but possibly empty) collection:
if (words == null)
{
return Enumerable.Empty<Tag>(); // You could do without LINQ by writing:
// return new Tag[] { };
}
Every method should run sanity checks on the arguments it accepts to ensure the arguments are valid input parameters. I would probably do something like
public static IEnumerable<Tag> CreateTags(IEnumerable<string> words)
{
if(words==null)
{
//either throw a new ArgumentException or
return null; //or return new Dictionary<string,int>();
}
Dictionary<string, int> tags = new Dictionary<string, int>();
foreach (string word in words)
{
int count = 1;
if (tags.ContainsKey(word))
{
count = tags[word] + 1;
}
tags[word] = count;
}
return tags.Select(kvp => new Tag(kvp.Key, kvp.Value));
}
As to why your "words" param is null, it would be helpful to see the CSV file you are trying to parse in.
Hope this helps!

C# Sanitize File Name

I recently have been moving a bunch of MP3s from various locations into a repository. I had been constructing the new file names using the ID3 tags (thanks, TagLib-Sharp!), and I noticed that I was getting a System.NotSupportedException:
"The given path's format is not supported."
This was generated by either File.Copy() or Directory.CreateDirectory().
It didn't take long to realize that my file names needed to be sanitized. So I did the obvious thing:
public static string SanitizePath_(string path, char replaceChar)
{
string dir = Path.GetDirectoryName(path);
foreach (char c in Path.GetInvalidPathChars())
dir = dir.Replace(c, replaceChar);
string name = Path.GetFileName(path);
foreach (char c in Path.GetInvalidFileNameChars())
name = name.Replace(c, replaceChar);
return dir + name;
}
To my surprise, I continued to get exceptions. It turned out that ':' is not in the set of Path.GetInvalidPathChars(), because it is valid in a path root. I suppose that makes sense - but this has to be a pretty common problem. Does anyone have some short code that sanitizes a path? The most thorough I've come up with this, but it feels like it is probably overkill.
// replaces invalid characters with replaceChar
public static string SanitizePath(string path, char replaceChar)
{
// construct a list of characters that can't show up in filenames.
// need to do this because ":" is not in InvalidPathChars
if (_BadChars == null)
{
_BadChars = new List<char>(Path.GetInvalidFileNameChars());
_BadChars.AddRange(Path.GetInvalidPathChars());
_BadChars = Utility.GetUnique<char>(_BadChars);
}
// remove root
string root = Path.GetPathRoot(path);
path = path.Remove(0, root.Length);
// split on the directory separator character. Need to do this
// because the separator is not valid in a filename.
List<string> parts = new List<string>(path.Split(new char[]{Path.DirectorySeparatorChar}));
// check each part to make sure it is valid.
for (int i = 0; i < parts.Count; i++)
{
string part = parts[i];
foreach (char c in _BadChars)
{
part = part.Replace(c, replaceChar);
}
parts[i] = part;
}
return root + Utility.Join(parts, Path.DirectorySeparatorChar.ToString());
}
Any improvements to make this function faster and less baroque would be much appreciated.
To clean up a file name you could do this
private static string MakeValidFileName( string name )
{
string invalidChars = System.Text.RegularExpressions.Regex.Escape( new string( System.IO.Path.GetInvalidFileNameChars() ) );
string invalidRegStr = string.Format( #"([{0}]*\.+$)|([{0}]+)", invalidChars );
return System.Text.RegularExpressions.Regex.Replace( name, invalidRegStr, "_" );
}
A shorter solution:
var invalids = System.IO.Path.GetInvalidFileNameChars();
var newName = String.Join("_", origFileName.Split(invalids, StringSplitOptions.RemoveEmptyEntries) ).TrimEnd('.');
Based on Andre's excellent answer but taking into account Spud's comment on reserved words, I made this version:
/// <summary>
/// Strip illegal chars and reserved words from a candidate filename (should not include the directory path)
/// </summary>
/// <remarks>
/// http://stackoverflow.com/questions/309485/c-sharp-sanitize-file-name
/// </remarks>
public static string CoerceValidFileName(string filename)
{
var invalidChars = Regex.Escape(new string(Path.GetInvalidFileNameChars()));
var invalidReStr = string.Format(#"[{0}]+", invalidChars);
var reservedWords = new []
{
"CON", "PRN", "AUX", "CLOCK$", "NUL", "COM0", "COM1", "COM2", "COM3", "COM4",
"COM5", "COM6", "COM7", "COM8", "COM9", "LPT0", "LPT1", "LPT2", "LPT3", "LPT4",
"LPT5", "LPT6", "LPT7", "LPT8", "LPT9"
};
var sanitisedNamePart = Regex.Replace(filename, invalidReStr, "_");
foreach (var reservedWord in reservedWords)
{
var reservedWordPattern = string.Format("^{0}\\.", reservedWord);
sanitisedNamePart = Regex.Replace(sanitisedNamePart, reservedWordPattern, "_reservedWord_.", RegexOptions.IgnoreCase);
}
return sanitisedNamePart;
}
And these are my unit tests
[Test]
public void CoerceValidFileName_SimpleValid()
{
var filename = #"thisIsValid.txt";
var result = PathHelper.CoerceValidFileName(filename);
Assert.AreEqual(filename, result);
}
[Test]
public void CoerceValidFileName_SimpleInvalid()
{
var filename = #"thisIsNotValid\3\\_3.txt";
var result = PathHelper.CoerceValidFileName(filename);
Assert.AreEqual("thisIsNotValid_3__3.txt", result);
}
[Test]
public void CoerceValidFileName_InvalidExtension()
{
var filename = #"thisIsNotValid.t\xt";
var result = PathHelper.CoerceValidFileName(filename);
Assert.AreEqual("thisIsNotValid.t_xt", result);
}
[Test]
public void CoerceValidFileName_KeywordInvalid()
{
var filename = "aUx.txt";
var result = PathHelper.CoerceValidFileName(filename);
Assert.AreEqual("_reservedWord_.txt", result);
}
[Test]
public void CoerceValidFileName_KeywordValid()
{
var filename = "auxillary.txt";
var result = PathHelper.CoerceValidFileName(filename);
Assert.AreEqual("auxillary.txt", result);
}
string clean = String.Concat(dirty.Split(Path.GetInvalidFileNameChars()));
there are a lot of working solutions here. just for the sake of completeness, here's an approach that doesn't use regex, but uses LINQ:
var invalids = Path.GetInvalidFileNameChars();
filename = invalids.Aggregate(filename, (current, c) => current.Replace(c, '_'));
Also, it's a very short solution ;)
I'm using the System.IO.Path.GetInvalidFileNameChars() method to check invalid characters and I've got no problems.
I'm using the following code:
foreach( char invalidchar in System.IO.Path.GetInvalidFileNameChars())
{
filename = filename.Replace(invalidchar, '_');
}
I wanted to retain the characters in some way, not just simply replace the character with an underscore.
One way I thought was to replace the characters with similar looking characters which are (in my situation), unlikely to be used as regular characters. So I took the list of invalid characters and found look-a-likes.
The following are functions to encode and decode with the look-a-likes.
This code does not include a complete listing for all System.IO.Path.GetInvalidFileNameChars() characters. So it is up to you to extend or utilize the underscore replacement for any remaining characters.
private static Dictionary<string, string> EncodeMapping()
{
//-- Following characters are invalid for windows file and folder names.
//-- \/:*?"<>|
Dictionary<string, string> dic = new Dictionary<string, string>();
dic.Add(#"\", "Ì"); // U+OOCC
dic.Add("/", "Í"); // U+OOCD
dic.Add(":", "¦"); // U+00A6
dic.Add("*", "¤"); // U+00A4
dic.Add("?", "¿"); // U+00BF
dic.Add(#"""", "ˮ"); // U+02EE
dic.Add("<", "«"); // U+00AB
dic.Add(">", "»"); // U+00BB
dic.Add("|", "│"); // U+2502
return dic;
}
public static string Escape(string name)
{
foreach (KeyValuePair<string, string> replace in EncodeMapping())
{
name = name.Replace(replace.Key, replace.Value);
}
//-- handle dot at the end
if (name.EndsWith(".")) name = name.CropRight(1) + "°";
return name;
}
public static string UnEscape(string name)
{
foreach (KeyValuePair<string, string> replace in EncodeMapping())
{
name = name.Replace(replace.Value, replace.Key);
}
//-- handle dot at the end
if (name.EndsWith("°")) name = name.CropRight(1) + ".";
return name;
}
You can select your own look-a-likes. I used the Character Map app in windows to select mine %windir%\system32\charmap.exe
As I make adjustments through discovery, I will update this code.
I think the problem is that you first call Path.GetDirectoryName on the bad string. If this has non-filename characters in it, .Net can't tell which parts of the string are directories and throws. You have to do string comparisons.
Assuming it's only the filename that is bad, not the entire path, try this:
public static string SanitizePath(string path, char replaceChar)
{
int filenamePos = path.LastIndexOf(Path.DirectorySeparatorChar) + 1;
var sb = new System.Text.StringBuilder();
sb.Append(path.Substring(0, filenamePos));
for (int i = filenamePos; i < path.Length; i++)
{
char filenameChar = path[i];
foreach (char c in Path.GetInvalidFileNameChars())
if (filenameChar.Equals(c))
{
filenameChar = replaceChar;
break;
}
sb.Append(filenameChar);
}
return sb.ToString();
}
I have had success with this in the past.
Nice, short and static :-)
public static string returnSafeString(string s)
{
foreach (char character in Path.GetInvalidFileNameChars())
{
s = s.Replace(character.ToString(),string.Empty);
}
foreach (char character in Path.GetInvalidPathChars())
{
s = s.Replace(character.ToString(), string.Empty);
}
return (s);
}
Here's an efficient lazy loading extension method based on Andre's code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace LT
{
public static class Utility
{
static string invalidRegStr;
public static string MakeValidFileName(this string name)
{
if (invalidRegStr == null)
{
var invalidChars = System.Text.RegularExpressions.Regex.Escape(new string(System.IO.Path.GetInvalidFileNameChars()));
invalidRegStr = string.Format(#"([{0}]*\.+$)|([{0}]+)", invalidChars);
}
return System.Text.RegularExpressions.Regex.Replace(name, invalidRegStr, "_");
}
}
}
Your code would be cleaner if you appended the directory and filename together and sanitized that rather than sanitizing them independently. As for sanitizing away the :, just take the 2nd character in the string. If it is equal to "replacechar", replace it with a colon. Since this app is for your own use, such a solution should be perfectly sufficient.
using System;
using System.IO;
using System.Linq;
using System.Text;
public class Program
{
public static void Main()
{
try
{
var badString = "ABC\\DEF/GHI<JKL>MNO:PQR\"STU\tVWX|YZA*BCD?EFG";
Console.WriteLine(badString);
Console.WriteLine(SanitizeFileName(badString, '.'));
Console.WriteLine(SanitizeFileName(badString));
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
}
private static string SanitizeFileName(string fileName, char? replacement = null)
{
if (fileName == null) { return null; }
if (fileName.Length == 0) { return ""; }
var sb = new StringBuilder();
var badChars = Path.GetInvalidFileNameChars().ToList();
foreach (var #char in fileName)
{
if (badChars.Contains(#char))
{
if (replacement.HasValue)
{
sb.Append(replacement.Value);
}
continue;
}
sb.Append(#char);
}
return sb.ToString();
}
}
Based #fiat's and #Andre's approach, I'd like to share my solution too.
Main difference:
its an extension method
regex is compiled at first use to save some time with a lot executions
reserved words are preserved
public static class StringPathExtensions
{
private static Regex _invalidPathPartsRegex;
static StringPathExtensions()
{
var invalidReg = System.Text.RegularExpressions.Regex.Escape(new string(Path.GetInvalidFileNameChars()));
_invalidPathPartsRegex = new Regex($"(?<reserved>^(CON|PRN|AUX|CLOCK\\$|NUL|COM0|COM1|COM2|COM3|COM4|COM5|COM6|COM7|COM8|COM9|LPT0|LPT1|LPT2|LPT3|LPT4|LPT5|LPT6|LPT7|LPT8|LPT9))|(?<invalid>[{invalidReg}:]+|\\.$)", RegexOptions.Compiled);
}
public static string SanitizeFileName(this string path)
{
return _invalidPathPartsRegex.Replace(path, m =>
{
if (!string.IsNullOrWhiteSpace(m.Groups["reserved"].Value))
return string.Concat("_", m.Groups["reserved"].Value);
return "_";
});
}
}

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