Data is Null. This method or property cannot be called on Null values

Learning to C#-the Nulls

Maintenance nightmare? Verify your models in C# match your database neighbour:

public class Movie
{
    public int Id { get; set; }
    public string? Genre { get; set; } // Nullable string? I didn't see it coming!
}
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C# 8 nullable feature is your new best buddy, embrace it with open arms in your .csproj file:

<PropertyGroup>
    <Nullable>enable</Nullable>
</PropertyGroup>
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We have just stepped into a null-free wonderland.

Guardians of the Schema

Remember, SQL schema is the law; neglect can lead to data misdemeanors. Keep the fields that could be null as nullable:

ALTER TABLE myTable
ALTER COLUMN myColumn VARCHAR(100) NULL;   // You have the right to be NULL!
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ISNULL function is also here to preserve law and order:

SELECT ISNULL(myColumn, 'Default') FROM myTable;   // Null, we’ve got you covered!
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Coping nulls: Stored procedures edition

Introduce aliases in stored procedures to keep null blues at bay:

CREATE PROCEDURE GetMovieGenre
    @MovieID INT,
    @Genre NVARCHAR(100) OUTPUT
AS
BEGIN
    SELECT @Genre = ISNULL(Genre, 'No Genre') FROM Movies WHERE Id = @MovieID;  // In genre we trust!
END
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Null Checks and Swaps: SQL Edition

Up your SQL game by learning null check:

SELECT myColumn FROM myTable WHERE myColumn IS NOT NULL;  
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And null swap:

SELECT NULLIF(myColumn, 'ValueToBecomeNull') FROM myTable;  
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Don't let the NULLs get you, you got them!

Use null-coalescing operator (??) in C# to assign default if a value is NULL:

public void PrintGenre(Movie movie)
{
    string genre = movie.Genre ?? "No Genre";    // Who said nulls ain't fun?
    Console.WriteLine(genre);
}
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Null Handling: EF Models Style

To tackle NULL woes, marry your Entity Framework models with the field properties of your tables. Bid adieu to .IsRequired(), if field can be null:

modelBuilder.Entity<Movie>()
    .Property(b => b.Genre)
    .IsRequired(false);   // Genre-ously nullable
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Application Logic Level: Null Combat

Smart defaults can null-proof your application logic:

if (movie.Genre == null)
{
    movie.Genre = "Unknown Genre";    // Mission: Null Impossible!
}
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Managing the NULLStorm: Advanced Techniques

Protect your code from NULLStorms:

• Arm yourself with unit tests for null cases
• Be the first one to manage null return values
• Win the war with nullable reference types