write list of objects to a file

Question

I\'ve got a class salesman in the following format:

class salesman
{
    public string name, address, email;
    public int sales;
}

I\'ve

Answer 1

I just wrote a blog post on saving an object's data to Binary, XML, or Json; well writing an object or list of objects to a file that is. Here are the functions to do it in the various formats. See my blog post for more details.

Binary

/// 

/// Writes the given object instance to a binary file.
/// Object type (and all child types) must be decorated with the [Serializable] attribute.
/// To prevent a variable from being serialized, decorate it with the [NonSerialized] attribute; cannot be applied to properties.
/// 
/// The type of object being written to the XML file.
/// The file path to write the object instance to.
/// The object instance to write to the XML file.
/// If false the file will be overwritten if it already exists. If true the contents will be appended to the file.
public static void WriteToBinaryFile(string filePath, T objectToWrite, bool append = false)
{
    using (Stream stream = File.Open(filePath, append ? FileMode.Append : FileMode.Create))
    {
        var binaryFormatter = new System.Runtime.Serialization.Formatters.Binary.BinaryFormatter();
        binaryFormatter.Serialize(stream, objectToWrite);
    }
}

/// 

/// Reads an object instance from a binary file.
/// 
/// The type of object to read from the XML.
/// The file path to read the object instance from.
/// Returns a new instance of the object read from the binary file.
public static T ReadFromBinaryFile(string filePath)
{
    using (Stream stream = File.Open(filePath, FileMode.Open))
    {
        var binaryFormatter = new System.Runtime.Serialization.Formatters.Binary.BinaryFormatter();
        return (T)binaryFormatter.Deserialize(stream);
    }
}

XML

Requires the System.Xml assembly to be included in your project.

/// 

/// Writes the given object instance to an XML file.
/// Only Public properties and variables will be written to the file. These can be any type though, even other classes.
/// If there are public properties/variables that you do not want written to the file, decorate them with the [XmlIgnore] attribute.
/// Object type must have a parameterless constructor.
/// 
/// The type of object being written to the file.
/// The file path to write the object instance to.
/// The object instance to write to the file.
/// If false the file will be overwritten if it already exists. If true the contents will be appended to the file.
public static void WriteToXmlFile(string filePath, T objectToWrite, bool append = false) where T : new()
{
    TextWriter writer = null;
    try
    {
        var serializer = new XmlSerializer(typeof(T));
        writer = new StreamWriter(filePath, append);
        serializer.Serialize(writer, objectToWrite);
    }
    finally
    {
        if (writer != null)
            writer.Close();
    }
}

/// 

/// Reads an object instance from an XML file.
/// Object type must have a parameterless constructor.
/// 
/// The type of object to read from the file.
/// The file path to read the object instance from.
/// Returns a new instance of the object read from the XML file.
public static T ReadFromXmlFile(string filePath) where T : new()
{
    TextReader reader = null;
    try
    {
        var serializer = new XmlSerializer(typeof(T));
        reader = new StreamReader(filePath);
        return (T)serializer.Deserialize(reader);
    }
    finally
    {
        if (reader != null)
            reader.Close();
    }
}

Json

You must include a reference to Newtonsoft.Json assembly, which can be obtained from the Json.NET NuGet Package.

/// 

/// Writes the given object instance to a Json file.
/// Object type must have a parameterless constructor.
/// Only Public properties and variables will be written to the file. These can be any type though, even other classes.
/// If there are public properties/variables that you do not want written to the file, decorate them with the [JsonIgnore] attribute.
/// 
/// The type of object being written to the file.
/// The file path to write the object instance to.
/// The object instance to write to the file.
/// If false the file will be overwritten if it already exists. If true the contents will be appended to the file.
public static void WriteToJsonFile(string filePath, T objectToWrite, bool append = false) where T : new()
{
    TextWriter writer = null;
    try
    {
        var contentsToWriteToFile = JsonConvert.SerializeObject(objectToWrite);
        writer = new StreamWriter(filePath, append);
        writer.Write(contentsToWriteToFile);
    }
    finally
    {
        if (writer != null)
            writer.Close();
    }
}

/// 

/// Reads an object instance from an Json file.
/// Object type must have a parameterless constructor.
/// 
/// The type of object to read from the file.
/// The file path to read the object instance from.
/// Returns a new instance of the object read from the Json file.
public static T ReadFromJsonFile(string filePath) where T : new()
{
    TextReader reader = null;
    try
    {
        reader = new StreamReader(filePath);
        var fileContents = reader.ReadToEnd();
        return JsonConvert.DeserializeObject(fileContents);
    }
    finally
    {
        if (reader != null)
            reader.Close();
    }
}

Example

// Write the list of salesman objects to file.
WriteToXmlFile>("C:\salesmen.txt", salesmanList);

// Read the list of salesman objects from the file back into a variable.
List salesmanList = ReadFromXmlFile>("C:\salesmen.txt");