Develop Reference

In my main, how to access string array in an array object? How to access parameter from constructor?

UML is attached. I want to create a readonly property of pre which is an array of string. When I create an object in the main and try to set name and pre it is showing me an error.
UML
using System;
class Unit
{
private string _name;
private string[] _pre;
public Unit(string name, string[] pre)
{
_name = name;
_pre = new string[2];
}
public string Name { get { return _name; } }
public string[] Pre { get { return _pre; } }
}
class Program
{
public static void DisplayInfo(Unit[] _u)
{
for (int i = 0; i < 2; i++)
{
Console.WriteLine(_u[i].Name + _u[i].Pre);
}
}
static void Main(string[] args)
{
Unit[] unitarraytest = new Unit[2];
unitarraytest[0] = new Unit("test 1", "test 3");
unitarraytest[1] = new Unit("test 2", "test 4");
DisplayInfo(unitarraytest);
}
}

Your example makes little sense. You Unit constructor takes a parameter for "Pre", but immediately throws it away and allocates a new empty string array instead. It should probably be written like
class Unit
{
public Unit(string name, string[] pre)
{
Name = name;
Pre = pre;
}
public string Name { get;}
public string[] Pre { get;}
}
When creating Unit objects you actually need to create an array for the "Pre" parameter. Like new Unit("Name", new []{"pre1", "pre2"});
And when outputting the strings you need to access the individual strings in the array, or combine them to a larger string, for example like Console.WriteLine(_u[i].Name + string.Join(" , ", _u[i].Pre));

fetch details from csv file on basis of name search c#

Step 1: I have created a C# application called : Student details
Step 2: Added four TextBoxes and named them as :
Image below to refer:
Studentname.Text
StudentSurname.Text
StudentCity.Text
StudentState.Text
DATA INSIDE CSV FILE
vikas,gadhi,mumbai,maharashtra
prem,yogi,kolkata,maha
roja,goal,orissa,oya
ram,kala,goa,barka
Issue is How do I fetch all the data(surname,city,state) of user prem into above textboxes studentsurname,studentcity,studentstate from csv file when I search the name in textbox 1 => studentname.Text as prem
Below is the Code where I am stuck at return null and code inside Load_Script_Click
void Connection_fetch_details(String searchName)
{
var strLines = File.ReadLines(filePath);
foreach (var line in strLines)
{
if (line.Split(',')[0].Equals(searchName))
{
Connection_fetch_details cd = new Connection_fetch_details()
{
username = line.Split(',')[1]
};
}
}
return;
}
private void Load_Script_Click(object sender, EventArgs e)
{
// load script is button
String con_env = textenv.Text.ToString();
//Address Address = GetAddress("vikas");
//textsurname.text = Address.Surname
Connection_fetch_details cd = Connection_fetch_details(con_env);
textusername.Text = cd.username;
}
==============================================================
Class file name : Address.class
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace DDL_SCRIPT_GENERATOR
{
public class Connection_fetch_details
{
public string username { get; set; }
}
}

The main problem is that your method is void, which means it doesn't return any value. So even though you may be finding a match, and creating a Connection_fetch_details object, you aren't returning that result back to the calling method.
This will fix that problem:
Connection_fetch_details Connection_fetch_details(String searchName)
{
var strLines = File.ReadLines(filePath);
foreach (var line in strLines)
{
if (line.Split(',')[0].Equals(searchName))
{
Connection_fetch_details cd = new Connection_fetch_details()
{
username = line.Split(',')[1]
};
return cd; //return the object containing the matched username
}
}
return null;
}
Now it will return a Connection_fetch_details object if there is a match, or null if there is no match.
Next, you asked about returning all the fields, not just one. For that you would need to
a) add more properties to your object
b) add more code to populate those properties from the CSV
c) add code to populate the textboxes with the results from the object.
I'm also going to rename "username" to something more relevant, since none of the field names you described in the question match that. I'm also going to rename your class to "Student", and rename your search method, for the same reason.
Here's an example:
Student searchStudent(String searchName)
{
var strLines = File.ReadLines(filePath);
foreach (var line in strLines)
{
var split = line.Split(',');
if (split[0].Equals(searchName))
{
Student s = new Student()
{
firstname = searchName,
surname = split[1],
city = split[2],
state = split[3]
};
return s; //return the object containing the matched name
}
}
return null;
}
private void Load_Script_Click(object sender, EventArgs e)
{
// load script is button
String con_env = textenv.Text.ToString();
//Address Address = GetAddress("vikas");
//textsurname.text = Address.Surname
Student st = searchStudent(con_env);
textsurname.Text = st.surname;
txtcity.Text = st.city;
txtstate.Text = st.state;
}
namespace DDL_SCRIPT_GENERATOR
{
public class Student
{
public string firstname { get; set; }
public string surname { get; set; }
public string city { get; set; }
public string state { get; set; }
}
}

To accomplish your goal you have to further separate your problem in more granular steps and also distinguish between what you show in your UI and what informations you hold in the background in which format.
Create a class with the desired properties
public class Student { public string Name { get; set; } ... }
Learn how to read a csv file into such an object by using an existing library like CsvHelper or CsvReader.
When you have something like List<Student> from this part. Learn how you can visualize such a thing by using some Binding (also depends on the visualization you use Winforms, WPF, etc.).
Depending on the visualization component it already supports filtering or you need to filter by yourself by using e.g. LINQ to get the matching elements students.Where(student => student.Name.StartsWith(search)).
So far a lot of smaller problems which is simply to much to answer in a single one. Please try to break down your problems into smaller ones and search for their solutions. If you get stuck, ask a new question. That's all I can do for you now.

Read values from a non-delimited string into class object

I have a string with the following structure:
Student Name________AgeAddress_______________________Bithday___Lvl
Example:
Jonh Smith 016Some place in NY, USA 01/01/2014L01
As you can see, there is no delimited character like | or ,
Also, there is no space between fields (if you check, there is no space between Age/Address and Birthday/Level.
The size of each field is static so if data's length is less then it will contains white spaces.
I have a class that need to be filled with that information:
public class StudentData
{
public char[] _name = new char[20];
public string name;
public char[] _age = new char[3];
public string age;
public char[] _address = new char[30];
public string address;
public char[] _bday = new char[10];
public string bday;
public char[] _level = new char[3];
public string level;
}
Is there any way to do this automatically and dynamically?
I mean I really don't want to code like this:
myClass.name = stringLine.substring(0,19);
myClass.age = stringLine.substring(20,22);
That's because I have way more fields that the ones added in this example & way more string lines with other different data.
Update: There were supposed to be a lot of spaces between "Smith" and "016", but I don't know how to edit it.
Update2: If I use StringReader.Read() I can evade to use substring and indexes, but it isn't still so dynamically because I would need to repeat those 3 lines for each field.
StringReader reader = new StringReader(stringLine);
reader.Read(myClass._name, 0 myClass._name.Length);
myClass.name = new string(myClass._name);

Given your requirement I came up with an interesting solution. All be-it it may be more complex and longer than using the String.SubString() method as stated.
However this solution is transferable to other types and other string. I used a concept of Attributes, Properties, and Reflection to parse a string by a Fixed Length and setting the class Properties.
Note I did change your StudentData class to follow a more conventional coding style. Following this handy guide on MSDN: http://msdn.microsoft.com/en-us/library/xzf533w0(v=vs.71).aspx
Here is the new StudentData class. Note it uses the properties as opposed to fields. (Not discussed here).
public class StudentData
{
string name;
string age;
string address;
string bday;
string level;
[FixedLengthDelimeter(0, 20)]
public string Name { get { return this.name; } set { this.name = value; } }
[FixedLengthDelimeter(1, 3)]
public string Age { get { return this.age; } set { this.age = value; } }
[FixedLengthDelimeter(2, 30)]
public string Address { get { return this.address; } set { this.address = value; } }
[FixedLengthDelimeter(3, 10)]
public string BDay { get { return this.bday; } set { this.bday = value; } }
[FixedLengthDelimeter(4, 3)]
public string Level { get { return this.level; } set { this.level = value; } }
}
Note on each of the properties there is an Attribute called FixedLengthDelimeter that takes two parameters.
OrderNumber
FixedLength
The OrderNumber parameter denotes the order in the string (not the position) but the order in which we process from the string. The second parameter denotes the Length of the string when parsing the string. Here is the full attribute class.
[AttributeUsage(AttributeTargets.Property, AllowMultiple = false)]
public sealed class FixedLengthDelimeterAttribute : Attribute
{
public FixedLengthDelimeterAttribute(int orderNumber, int fixedLength)
{
this.fixedLength = fixedLength;
this.orderNumber = orderNumber;
}
readonly int fixedLength;
readonly int orderNumber;
public int FixedLength { get { return this.fixedLength; } }
public int OrderNumber { get { return this.orderNumber; } }
}
Now the attribute is simple enough. Accepts the two paramters we discussed eariler in the constructor.
Finally there is another method to parse the string into the object type such as.
public static class FixedLengthFormatter
{
public static T ParseString<T>(string inputString)
{
Type tType = typeof(T);
var properties = tType.GetProperties(BindingFlags.Instance | BindingFlags.Public); //;.Where(x => x.GetCustomAttributes(typeof(FixedLengthDelimeterAttribute), false).Count() > 0);
T newT = (T)Activator.CreateInstance(tType);
Dictionary<PropertyInfo, FixedLengthDelimeterAttribute> dictionary = new Dictionary<PropertyInfo, FixedLengthDelimeterAttribute>();
foreach (var property in properties)
{
var atts = property.GetCustomAttributes(typeof(FixedLengthDelimeterAttribute), false);
if (atts.Length == 0)
continue;
dictionary[property] = atts[0] as FixedLengthDelimeterAttribute;
}
foreach (var kvp in dictionary.OrderBy(x => x.Value.OrderNumber))
{
int length = kvp.Value.FixedLength;
if (inputString.Length < length)
throw new Exception("error on attribute order number:" + kvp.Value.OrderNumber + " the string is too short.");
string piece = inputString.Substring(0, length);
inputString = inputString.Substring(length);
kvp.Key.SetValue(newT, piece.Trim(), null);
}
return newT;
}
}
The method above is what does the string parsing. It is a pretty basic utility that reads all the properties that have the FixedLengthDelimeter attribute applied a Dictionary. That dictionary is then enumerated (ordered by OrderNumber) and then calling the SubString() method twice on the input string.
The first substring is to parse the next Token while the second substring resets the inputString to start processing the next token.
Finally as it is parsing the string it is then applying the parsed string to the property of the class Type provided to the method.
Now this can be used simply like this:
string data1 = "Jonh Smith 016Some place in NY, USA 01/01/2014L01";
StudentData student = FixedLengthFormatter.ParseString<StudentData>(data1);
What this does:
Parses a string against property attributes in a fixed length format.
What this does not do:
It does convert the parsed strings to another type. Therefore all the properties must be a string. (this can be easily adapted by adding some type casting logic in).
It is not well tested. This is only tested against a few samples.
It is not by all means the only or best solution out there.

You could use FileHelpers library (NuGet).
Just define the structure of your input file with attributes:
[FixedLengthRecord]
public class StudentData
{
[FieldFixedLength(20)]
[FieldTrim(TrimMode.Right)]
public string name;
[FieldFixedLength(3)]
public string age;
[FieldFixedLength(30)]
[FieldTrim(TrimMode.Right)]
public string address;
[FieldFixedLength(10)]
public string bday;
[FieldFixedLength(3)]
public string level;
}
Then simply read the file using FileHelperEngine<T>:
var engine = new FileHelperEngine<StudentData>();
var students = engine.ReadFile(filename);

C# custom object in combobox

I am relatively new to C# (WinForms), and had a question regarding combo boxes. I have a combo box of Reviewer objects (it is a custom class with an overridden ToString method) and am currently attempting to go through all the checked items and use them to generate a setup file.
Here is how the combo box is populated (populated on form load). Parameters is just a collection of linked lists and parsing code.
for (int i = 0; i < parameters.GetUsers().Count; i++)
{
UserList.Items.Add(parameters.GetUsersArray()[i], parameters.GetUsersArray()[i].isSelected());
}
Here is how I am trying to read it. setup is a StringBuilder. The problem is that GetID is not defined. Does the add function above cast the Reviewer object to a Object object? It looks a little funny since it creates a file fed into a Perl script. A sample desired output line looks like this: inspector0 => "chg0306",
for (int i = 0; i < UserList.CheckedItems.Count; i++)
{
setup.AppendLine("inspector" + i.ToString() + " => \t \"" +
UserList.CheckedItems[i].GetID() + "\",");
}
Here is the users class: (Sample User is ID = aaa0000 name: Bob Joe)
public class Reviewer
{
private string name;
private string id;
private bool selected;
public Reviewer(string newName, string newID, bool newSelected)
{
name = newName;
id = newID;
selected = newSelected;
}
public string GetName()
{
return name;
}
public override string ToString()
{
//string retVal = new string(' ', id.Length + name.Length + 1);
string retVal = id + '\t' + name;
return retVal;
}
public string GetID()
{
return id;
}
public bool isSelected()
{
return selected;
}
}
For posterity, here is the Parameters class:
public class ParameterLists
{
public ParameterLists()
{
projects = new LinkedList<string>();
reviewers = new LinkedList<Reviewer>();
}
public enum FileContents {
PROJECT_LIST,
USERS_LIST,
}
public LinkedList<Reviewer> GetUsers()
{
return reviewers;
}
public LinkedList<string> GetProjects()
{
return projects;
}
public Reviewer[] GetUsersArray()
{
Reviewer[] userArray = new Reviewer[reviewers.Count];
reviewers.CopyTo(userArray, 0);
return userArray;
}
public string[] GetProjectsArray()
{
String[] projectArray = new String[projects.Count];
projects.CopyTo(projectArray, 0);
return projectArray;
}
public void LoadParameters(string fileName)
{
//Reads the parameters from the input file.
}
private void CreateDefaultFile(string fileName)
{
// Create the file from the defaultfile , if it exists.
// Otherwise create a blank default file.
}
private LinkedList <string> projects;
private LinkedList <Reviewer> reviewers;
}
I am probably missing something simple, coming from embedded C++. Any help would be appreciated.

You have to cast that object:
((Reviewer)UserList.CheckedItems[i]).GetID()

Importing an Excel Sheet and Validate the Imported Data with Loosely Coupled

I am trying to develop a module which will read excel sheets (possibly from other data sources too, so it should be loosely coupled) and convert them into Entities so to save.
The logic will be this:
The excel sheet can be in different format, for example column names in Excel sheet can be different so my system needs to be able to map different fields to my entities.
For now I will be assuming the format defined above will be same and hardcoded for now instead of coming from database dynamically after set on a configuration mapping UI kinda thing.
The data needs to be validated before even get mapped. So I should be able validate it beforehand against something. We're not using like XSD or something else so I should validate it against the object structure I am using as a template for importing.
The problem is, I put together some things together but I don't say I liked what I did. My Question is how I can improve the code below and make things more modular and fix the validation issues.
The code below is a mock-up and is not expected to work, just to see some structure of the design.
This is code I've come up with so far, and I've realized one thing that I need to improve my design patterns skills but for now I need your help, if you could help me:
//The Controller, a placeholder
class UploadController
{
//Somewhere here we call appropriate class and methods in order to convert
//excel sheet to dataset
}
After we uploaded file using an MVC Controller, there could be different controllers specialized to import certain behaviors, in this example I will uploading person related tables,
interface IDataImporter
{
void Import(DataSet dataset);
}
//We can use many other importers besides PersonImporter
class PersonImporter : IDataImporter
{
//We divide dataset to approprate data tables and call all the IImportActions
//related to Person data importing
//We call inserting to database functions here of the DataContext since this way
//we can do less db roundtrip.
public string PersonTableName {get;set;}
public string DemographicsTableName {get;set;}
public Import(Dataset dataset)
{
CreatePerson();
CreateDemograhics();
}
//We put different things in different methods to clear the field. High cohesion.
private void CreatePerson(DataSet dataset)
{
var personDataTable = GetDataTable(dataset,PersonTableName);
IImportAction addOrUpdatePerson = new AddOrUpdatePerson();
addOrUpdatePerson.MapEntity(personDataTable);
}
private void CreateDemograhics(DataSet dataset)
{
var demographicsDataTable = GetDataTable(dataset,DemographicsTableName);
IImportAction demoAction = new AddOrUpdateDemographic(demographicsDataTable);
demoAction.MapEntity();
}
private DataTable GetDataTable(DataSet dataset, string tableName)
{
return dataset.Tables[tableName];
}
}
I have IDataImporter and specialized concrete class PersonImporter. However, I am not sure it looks good so far since things should be SOLID so basically easy to extend later in the project cycle, this will be a foundation for future improvements, lets keep going:
IImportActions are where the magic mostly happens. Instead of designing things table based, I am developing it behavior based so one can call any of them to import things in more modular model. For example a table may have 2 different actions.
interface IImportAction
{
void MapEntity(DataTable table);
}
//A sample import action, AddOrUpdatePerson
class AddOrUpdatePerson : IImportAction
{
//Consider using default values as well?
public string FirstName {get;set;}
public string LastName {get;set;}
public string EmployeeId {get;set;}
public string Email {get;set;}
public void MapEntity(DataTable table)
{
//Each action is producing its own data context since they use
//different actions.
using(var dataContext = new DataContext())
{
foreach(DataRow row in table.Rows)
{
if(!emailValidate(row[Email]))
{
LoggingService.LogWarning(emailValidate.ValidationMessage);
}
var person = new Person(){
FirstName = row[FirstName],
LastName = row[LastName],
EmployeeId = row[EmployeeId],
Email = row[Email]
};
dataContext.SaveObject(person);
}
dataContext.SaveChangesToDatabase();
}
}
}
class AddOrUpdateDemographic: IImportAction
{
static string Name {get;set;}
static string EmployeeId {get;set;}
//So here for example, we will need to save dataContext first before passing it in
//to get the PersonId from Person (we're assuming that we need PersonId for Demograhics)
public void MapEntity(DataTable table)
{
using(var dataContext = new DataCOntext())
{
foreach(DataRow row in table.Rows)
{
var demograhic = new Demographic(){
Name = row[Name],
PersonId = dataContext.People.First(t => t.EmployeeId = int.Parse(row["EmpId"]))
};
dataContext.SaveObject(person);
}
dataContext.SaveChangesToDatabase();
}
}
}
And the validation, which mostly where I suck at unfortunately. The validation needs to be easy to extend and loosely coupled and also I need to be able to call this validation beforehand instead of adding everything.
public static class ValidationFactory
{
public static Lazy<IFieldValidation> PhoneValidation = new Lazy<IFieldValidation>(()=>new PhoneNumberValidation());
public static Lazy<IFieldValidation> EmailValidation = new Lazy<IFieldValidation>(()=>new EmailValidation());
//etc.
}
interface IFieldValidation
{
string ValidationMesage{get;set;}
bool Validate(object value);
}
class PhoneNumberValidation : IFieldValidation
{
public string ValidationMesage{get;set;}
public bool Validate(object value)
{
var validated = true; //lets say...
var innerValue = (string) value;
//validate innerValue using Regex or something
//if validation fails, then set ValidationMessage propert for logging.
return validated;
}
}
class EmailValidation : IFieldValidation
{
public string ValidationMesage{get;set;}
public bool Validate(object value)
{
var validated = true; //lets say...
var innerValue = (string) value;
//validate innerValue using Regex or something
//if validation fails, then set ValidationMessage propert for logging.
return validated;
}
}

I have done the same thing on a project. The difference is that I didn't have to import Excel sheets, but CSV files. I created a CSVValueProvider. And, therefore, the CSV data was bound to my IEnumerable model automatically.
As for validation, I figured that going through all rows, and cells, and validating them one by one is not very efficient, especially when the CSV file has thousands of records. So, what I did was that I created some validation methods that went through the CSV data column by column, instead of row by row, and did a linq query on each column and returned the row numbers of the cells with invalid data. Then, added the invalid row number/column names to ModelState.
UPDATE:
Here is what I have done...
CSVReader Class:
// A class that can read and parse the data in a CSV file.
public class CSVReader
{
// Regex expression that's used to parse the data in a line of a CSV file
private const string ESCAPE_SPLIT_REGEX = "({1}[^{1}]*{1})*(?<Separator>{0})({1}[^{1}]*{1})*";
// String array to hold the headers (column names)
private string[] _headers;
// List of string arrays to hold the data in the CSV file. Each string array in the list represents one line (row).
private List<string[]> _rows;
// The StreamReader class that's used to read the CSV file.
private StreamReader _reader;
public CSVReader(StreamReader reader)
{
_reader = reader;
Parse();
}
// Reads and parses the data from the CSV file
private void Parse()
{
_rows = new List<string[]>();
string[] row;
int rowNumber = 1;
var headerLine = "RowNumber," + _reader.ReadLine();
_headers = GetEscapedSVs(headerLine);
rowNumber++;
while (!_reader.EndOfStream)
{
var line = rowNumber + "," + _reader.ReadLine();
row = GetEscapedSVs(line);
_rows.Add(row);
rowNumber++;
}
_reader.Close();
}
private string[] GetEscapedSVs(string data)
{
if (!data.EndsWith(","))
data = data + ",";
return GetEscapedSVs(data, ",", "\"");
}
// Parses each row by using the given separator and escape characters
private string[] GetEscapedSVs(string data, string separator, string escape)
{
string[] result = null;
int priorMatchIndex = 0;
MatchCollection matches = Regex.Matches(data, string.Format(ESCAPE_SPLIT_REGEX, separator, escape));
// Skip empty rows...
if (matches.Count > 0)
{
result = new string[matches.Count];
for (int index = 0; index <= result.Length - 2; index++)
{
result[index] = data.Substring(priorMatchIndex, matches[index].Groups["Separator"].Index - priorMatchIndex);
priorMatchIndex = matches[index].Groups["Separator"].Index + separator.Length;
}
result[result.Length - 1] = data.Substring(priorMatchIndex, data.Length - priorMatchIndex - 1);
for (int index = 0; index <= result.Length - 1; index++)
{
if (Regex.IsMatch(result[index], string.Format("^{0}.*[^{0}]{0}$", escape)))
result[index] = result[index].Substring(1, result[index].Length - 2);
result[index] = result[index].Replace(escape + escape, escape);
if (result[index] == null || result[index] == escape)
result[index] = "";
}
}
return result;
}
// Returns the number of rows
public int RowCount
{
get
{
if (_rows == null)
return 0;
return _rows.Count;
}
}
// Returns the number of headers (columns)
public int HeaderCount
{
get
{
if (_headers == null)
return 0;
return _headers.Length;
}
}
// Returns the value in a given column name and row index
public object GetValue(string columnName, int rowIndex)
{
if (rowIndex >= _rows.Count)
{
return null;
}
var row = _rows[rowIndex];
int colIndex = GetColumnIndex(columnName);
if (colIndex == -1 || colIndex >= row.Length)
{
return null;
}
var value = row[colIndex];
return value;
}
// Returns the column index of the provided column name
public int GetColumnIndex(string columnName)
{
int index = -1;
for (int i = 0; i < _headers.Length; i++)
{
if (_headers[i].Replace(" ","").Equals(columnName, StringComparison.CurrentCultureIgnoreCase))
{
index = i;
return index;
}
}
return index;
}
}
CSVValueProviderFactory Class:
public class CSVValueProviderFactory : ValueProviderFactory
{
public override IValueProvider GetValueProvider(ControllerContext controllerContext)
{
var uploadedFiles = controllerContext.HttpContext.Request.Files;
if (uploadedFiles.Count > 0)
{
var file = uploadedFiles[0];
var extension = file.FileName.Split('.').Last();
if (extension.Equals("csv", StringComparison.CurrentCultureIgnoreCase))
{
if (file.ContentLength > 0)
{
var stream = file.InputStream;
var csvReader = new CSVReader(new StreamReader(stream, Encoding.Default, true));
return new CSVValueProvider(controllerContext, csvReader);
}
}
}
return null;
}
}
CSVValueProvider Class:
// Represents a value provider for the data in an uploaded CSV file.
public class CSVValueProvider : IValueProvider
{
private CSVReader _csvReader;
public CSVValueProvider(ControllerContext controllerContext, CSVReader csvReader)
{
if (controllerContext == null)
{
throw new ArgumentNullException("controllerContext");
}
if (csvReader == null)
{
throw new ArgumentNullException("csvReader");
}
_csvReader = csvReader;
}
public bool ContainsPrefix(string prefix)
{
if (prefix.Contains('[') && prefix.Contains(']'))
{
if (prefix.Contains('.'))
{
var header = prefix.Split('.').Last();
if (_csvReader.GetColumnIndex(header) == -1)
{
return false;
}
}
int index = int.Parse(prefix.Split('[').Last().Split(']').First());
if (index >= _csvReader.RowCount)
{
return false;
}
}
return true;
}
public ValueProviderResult GetValue(string key)
{
if (!key.Contains('[') || !key.Contains(']') || !key.Contains('.'))
{
return null;
}
object value = null;
var header = key.Split('.').Last();
int index = int.Parse(key.Split('[').Last().Split(']').First());
value = _csvReader.GetValue(header, index);
if (value == null)
{
return null;
}
return new ValueProviderResult(value, value.ToString(), CultureInfo.CurrentCulture);
}
}
For the validation, as I mentioned before, I figured that it would not be efficient to do it using DataAnnotation attributes. A row by row validation of the data would take a long time for CSV files with thousands of rows. So, I decided to validate the data in the Controller after the Model Binding is done. I should also mention that I needed to validate the data in the CSV file against some data in the database. If you just need to validate things like Email Address or Phone Number, you might as well just use DataAnnotation.
Here is a sample method for validating the Email Address column:
private void ValidateEmailAddress(IEnumerable<CSVViewModel> csvData)
{
var invalidRows = csvData.Where(d => ValidEmail(d.EmailAddress) == false).ToList();
foreach (var invalidRow in invalidRows)
{
var key = string.Format("csvData[{0}].{1}", invalidRow.RowNumber - 2, "EmailAddress");
ModelState.AddModelError(key, "Invalid Email Address");
}
}
private static bool ValidEmail(string email)
{
if(email == "")
return false;
else
return new System.Text.RegularExpressions.Regex(#"^[\w-\.]+#([\w-]+\.)+[\w-]{2,6}$").IsMatch(email);
}
UPDATE 2:
For validation using DataAnnotaion, you just use DataAnnotation attributes in your CSVViewModel like below (the CSVViewModel is the class that your CSV data will be bound to in your Controller Action):
public class CSVViewModel
{
// User proper names for your CSV columns, these are just examples...
[Required]
public int Column1 { get; set; }
[Required]
[StringLength(30)]
public string Column2 { get; set; }
}