Empty string if null

I have this in my code:

SelectList(blah, "blah", "blah", cu.Customer.CustomerID.ToString())

It gives a error when it returns null, how can I make it CustomerID is an empty string if it is null?

asked Nov 2 '09 at 9:41

Lasse Edsvik

4,420135997

1

Is CustomerID the null value, or is the Customer itself null? Also, what is the type of CustomerID?
– Thorarin
Nov 2 '09 at 9:52

add a comment |

I have this in my code:

SelectList(blah, "blah", "blah", cu.Customer.CustomerID.ToString())

It gives a error when it returns null, how can I make it CustomerID is an empty string if it is null?

asked Nov 2 '09 at 9:41

Lasse Edsvik

4,420135997

1

Is CustomerID the null value, or is the Customer itself null? Also, what is the type of CustomerID?
– Thorarin
Nov 2 '09 at 9:52

add a comment |

I have this in my code:

SelectList(blah, "blah", "blah", cu.Customer.CustomerID.ToString())

It gives a error when it returns null, how can I make it CustomerID is an empty string if it is null?

asked Nov 2 '09 at 9:41

Lasse Edsvik

4,420135997

I have this in my code:

SelectList(blah, "blah", "blah", cu.Customer.CustomerID.ToString())

It gives a error when it returns null, how can I make it CustomerID is an empty string if it is null?

c# asp.net-mvc

asked Nov 2 '09 at 9:41

Lasse Edsvik

4,420135997

asked Nov 2 '09 at 9:41

Lasse Edsvik

4,420135997

asked Nov 2 '09 at 9:41

Lasse Edsvik

4,420135997

asked Nov 2 '09 at 9:41

Lasse Edsvik

4,420135997

asked Nov 2 '09 at 9:41

Lasse Edsvik

4,420135997

1

Is CustomerID the null value, or is the Customer itself null? Also, what is the type of CustomerID?
– Thorarin
Nov 2 '09 at 9:52

add a comment |

1

Is CustomerID the null value, or is the Customer itself null? Also, what is the type of CustomerID?
– Thorarin
Nov 2 '09 at 9:52

Is CustomerID the null value, or is the Customer itself null? Also, what is the type of CustomerID?
– Thorarin
Nov 2 '09 at 9:52

add a comment |

5 Answers
5

active

oldest

votes

(Update for C# 6.0)

If you are using C# 6 or newer (Visual Studio 2015 or newer), then you can achieve this using the null-conditional operator ?.:

var customerId = cu.Customer?.CustomerId.ToString() ?? "";

One useful property of the null-conditional operator is that it can also be "chained" if you want to test if several nested properties are null:

// ensure (a != null) && (b != null) && (c != null) before invoking

// a.b.c.CustomerId, otherwise return "" (short circuited at first encountered null)

var customerId = a?.b?.c?.CustomerId.ToString() ?? "";

For C# versions prior to 6.0 (VS2013 or older), you could coalesce it like this:

string customerId = cu.Customer != null ? cu.Customer.CustomerID.ToString() : "";

Simply check if the object is non-null before you try to access its members, and return an empty string otherwise.

Apart from that, there are situations where null object pattern is useful. That would mean that you ensure that your Customer's parent class (type of cu in this case) always return an actual instance of an object, even if it is "Empty". Check this link for an example, if you think it may apply to your problem: How do I create a Null Object in C#.

edited May 23 '17 at 12:32

Community♦

answered Nov 2 '09 at 9:43

Groo

35.2k1483158

add a comment |

It depends of the type of CustomerID.

If CustomerID is a string then you can use the null coalescing operator:

SelectList(blah, "blah", "blah", cu.Customer.CustomerID ?? string.Empty)

If CustomerID is a Nullable<T>, then you can use:

SelectList(blah, "blah", "blah", cu.Customer.CustomerID.ToString())

This will work because the ToString() method of Nullable<T> returns an empty string if the instance is null (technically if the HasValue property is false).

edited Nov 2 '09 at 10:02

answered Nov 2 '09 at 9:49

adrianbanks

65.6k18142181

add a comment |

(C# 2.0 - C# 5.0)

The ternary operator works, but if you want even shorter expression working on arbitrary objects you can use:

(myObject ?? "").ToString()

Here is real-life example from my code:

 private HtmlTableCell CreateTableCell(object cellContents)

 {

     return new HtmlTableCell()

     {

         InnerText = (cellContents ?? "").ToString()             

     };

 }

edited Nov 19 '18 at 17:24

answered Jan 20 '15 at 20:01

DKroot

756617

One of the outcomes of this code is redundant "".ToString(), moreover (myObject ?? "") will work only if myObject was a string in the first place, making .ToString() even more unnecessary. I think you meant myObject?.ToString() ?? "".
– ensisNoctis
Nov 2 '18 at 20:24

1

@ensisNoctis 1. This was written at the time we had C# 5, which didn't have ?. operator. For C# 6+, I'd use ?.. 2. .ToString() works on objects just fine. I stand by my answer scoped to C# 2 - C# 5: updated to clarify.
– DKroot
Nov 19 '18 at 17:27

Fine with me :)
– ensisNoctis
Nov 20 '18 at 12:05

add a comment |

SelectList(blah, "blah", "blah", 

(cu.Customer.CustomerID!=null?cu.Customer.CustomerID.ToString():"")

)

answered Nov 2 '09 at 9:44

Palantir

18k86380

add a comment |

Please don't use this in production :

/// <summary>

/// I most certainly don't recommend using this in production but when one can abuse delegates, one should :)

/// </summary>

public static class DirtyHelpers

{

    public static TVal SafeGet<THolder, TVal>(this THolder holder, Func<TVal> extract) where THolder : class

    {

        return null == holder ? default(TVal) : extract();

    }



    public static void Sample(String name)

    {

        int len = name.SafeGet(()=> name.Length);

    }

}

answered Nov 2 '09 at 11:34

Florian Doyon

3,2181931

add a comment |

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5 Answers
5

active

oldest

votes

5 Answers
5

active

oldest

votes

(Update for C# 6.0)

If you are using C# 6 or newer (Visual Studio 2015 or newer), then you can achieve this using the null-conditional operator ?.:

var customerId = cu.Customer?.CustomerId.ToString() ?? "";

One useful property of the null-conditional operator is that it can also be "chained" if you want to test if several nested properties are null:

// ensure (a != null) && (b != null) && (c != null) before invoking

// a.b.c.CustomerId, otherwise return "" (short circuited at first encountered null)

var customerId = a?.b?.c?.CustomerId.ToString() ?? "";

For C# versions prior to 6.0 (VS2013 or older), you could coalesce it like this:

string customerId = cu.Customer != null ? cu.Customer.CustomerID.ToString() : "";

Simply check if the object is non-null before you try to access its members, and return an empty string otherwise.

edited May 23 '17 at 12:32

Community♦

answered Nov 2 '09 at 9:43

Groo

35.2k1483158

add a comment |

(Update for C# 6.0)

If you are using C# 6 or newer (Visual Studio 2015 or newer), then you can achieve this using the null-conditional operator ?.:

var customerId = cu.Customer?.CustomerId.ToString() ?? "";

One useful property of the null-conditional operator is that it can also be "chained" if you want to test if several nested properties are null:

// ensure (a != null) && (b != null) && (c != null) before invoking

// a.b.c.CustomerId, otherwise return "" (short circuited at first encountered null)

var customerId = a?.b?.c?.CustomerId.ToString() ?? "";

For C# versions prior to 6.0 (VS2013 or older), you could coalesce it like this:

string customerId = cu.Customer != null ? cu.Customer.CustomerID.ToString() : "";

Simply check if the object is non-null before you try to access its members, and return an empty string otherwise.

edited May 23 '17 at 12:32

Community♦

answered Nov 2 '09 at 9:43

Groo

35.2k1483158

add a comment |

(Update for C# 6.0)

If you are using C# 6 or newer (Visual Studio 2015 or newer), then you can achieve this using the null-conditional operator ?.:

var customerId = cu.Customer?.CustomerId.ToString() ?? "";

One useful property of the null-conditional operator is that it can also be "chained" if you want to test if several nested properties are null:

// ensure (a != null) && (b != null) && (c != null) before invoking

// a.b.c.CustomerId, otherwise return "" (short circuited at first encountered null)

var customerId = a?.b?.c?.CustomerId.ToString() ?? "";

For C# versions prior to 6.0 (VS2013 or older), you could coalesce it like this:

string customerId = cu.Customer != null ? cu.Customer.CustomerID.ToString() : "";

Simply check if the object is non-null before you try to access its members, and return an empty string otherwise.

edited May 23 '17 at 12:32

Community♦

answered Nov 2 '09 at 9:43

Groo

35.2k1483158

(Update for C# 6.0)

If you are using C# 6 or newer (Visual Studio 2015 or newer), then you can achieve this using the null-conditional operator ?.:

var customerId = cu.Customer?.CustomerId.ToString() ?? "";

One useful property of the null-conditional operator is that it can also be "chained" if you want to test if several nested properties are null:

// ensure (a != null) && (b != null) && (c != null) before invoking

// a.b.c.CustomerId, otherwise return "" (short circuited at first encountered null)

var customerId = a?.b?.c?.CustomerId.ToString() ?? "";

For C# versions prior to 6.0 (VS2013 or older), you could coalesce it like this:

string customerId = cu.Customer != null ? cu.Customer.CustomerID.ToString() : "";

Simply check if the object is non-null before you try to access its members, and return an empty string otherwise.

edited May 23 '17 at 12:32

Community♦

answered Nov 2 '09 at 9:43

Groo

35.2k1483158

edited May 23 '17 at 12:32

Community♦

edited May 23 '17 at 12:32

Community♦

edited May 23 '17 at 12:32

Community♦

answered Nov 2 '09 at 9:43

Groo

35.2k1483158

answered Nov 2 '09 at 9:43

Groo

35.2k1483158

answered Nov 2 '09 at 9:43

Groo

35.2k1483158

add a comment |

It depends of the type of CustomerID.

If CustomerID is a string then you can use the null coalescing operator:

SelectList(blah, "blah", "blah", cu.Customer.CustomerID ?? string.Empty)

If CustomerID is a Nullable<T>, then you can use:

SelectList(blah, "blah", "blah", cu.Customer.CustomerID.ToString())

This will work because the ToString() method of Nullable<T> returns an empty string if the instance is null (technically if the HasValue property is false).

edited Nov 2 '09 at 10:02

answered Nov 2 '09 at 9:49

adrianbanks

65.6k18142181

add a comment |

It depends of the type of CustomerID.

If CustomerID is a string then you can use the null coalescing operator:

SelectList(blah, "blah", "blah", cu.Customer.CustomerID ?? string.Empty)

If CustomerID is a Nullable<T>, then you can use:

SelectList(blah, "blah", "blah", cu.Customer.CustomerID.ToString())

This will work because the ToString() method of Nullable<T> returns an empty string if the instance is null (technically if the HasValue property is false).

edited Nov 2 '09 at 10:02

answered Nov 2 '09 at 9:49

adrianbanks

65.6k18142181

add a comment |

It depends of the type of CustomerID.

If CustomerID is a string then you can use the null coalescing operator:

SelectList(blah, "blah", "blah", cu.Customer.CustomerID ?? string.Empty)

If CustomerID is a Nullable<T>, then you can use:

SelectList(blah, "blah", "blah", cu.Customer.CustomerID.ToString())

This will work because the ToString() method of Nullable<T> returns an empty string if the instance is null (technically if the HasValue property is false).

edited Nov 2 '09 at 10:02

answered Nov 2 '09 at 9:49

adrianbanks

65.6k18142181

It depends of the type of CustomerID.

If CustomerID is a string then you can use the null coalescing operator:

SelectList(blah, "blah", "blah", cu.Customer.CustomerID ?? string.Empty)

If CustomerID is a Nullable<T>, then you can use:

SelectList(blah, "blah", "blah", cu.Customer.CustomerID.ToString())

This will work because the ToString() method of Nullable<T> returns an empty string if the instance is null (technically if the HasValue property is false).

edited Nov 2 '09 at 10:02

answered Nov 2 '09 at 9:49

adrianbanks

65.6k18142181

edited Nov 2 '09 at 10:02

answered Nov 2 '09 at 9:49

adrianbanks

65.6k18142181

answered Nov 2 '09 at 9:49

adrianbanks

65.6k18142181

answered Nov 2 '09 at 9:49

adrianbanks

65.6k18142181

add a comment |

(C# 2.0 - C# 5.0)

The ternary operator works, but if you want even shorter expression working on arbitrary objects you can use:

(myObject ?? "").ToString()

Here is real-life example from my code:

 private HtmlTableCell CreateTableCell(object cellContents)

 {

     return new HtmlTableCell()

     {

         InnerText = (cellContents ?? "").ToString()             

     };

 }

edited Nov 19 '18 at 17:24

answered Jan 20 '15 at 20:01

DKroot

756617

One of the outcomes of this code is redundant "".ToString(), moreover (myObject ?? "") will work only if myObject was a string in the first place, making .ToString() even more unnecessary. I think you meant myObject?.ToString() ?? "".
– ensisNoctis
Nov 2 '18 at 20:24

1

@ensisNoctis 1. This was written at the time we had C# 5, which didn't have ?. operator. For C# 6+, I'd use ?.. 2. .ToString() works on objects just fine. I stand by my answer scoped to C# 2 - C# 5: updated to clarify.
– DKroot
Nov 19 '18 at 17:27

Fine with me :)
– ensisNoctis
Nov 20 '18 at 12:05

add a comment |

(C# 2.0 - C# 5.0)

The ternary operator works, but if you want even shorter expression working on arbitrary objects you can use:

(myObject ?? "").ToString()

Here is real-life example from my code:

 private HtmlTableCell CreateTableCell(object cellContents)

 {

     return new HtmlTableCell()

     {

         InnerText = (cellContents ?? "").ToString()             

     };

 }

edited Nov 19 '18 at 17:24

answered Jan 20 '15 at 20:01

DKroot

756617

One of the outcomes of this code is redundant "".ToString(), moreover (myObject ?? "") will work only if myObject was a string in the first place, making .ToString() even more unnecessary. I think you meant myObject?.ToString() ?? "".
– ensisNoctis
Nov 2 '18 at 20:24

1

@ensisNoctis 1. This was written at the time we had C# 5, which didn't have ?. operator. For C# 6+, I'd use ?.. 2. .ToString() works on objects just fine. I stand by my answer scoped to C# 2 - C# 5: updated to clarify.
– DKroot
Nov 19 '18 at 17:27

Fine with me :)
– ensisNoctis
Nov 20 '18 at 12:05

add a comment |

(C# 2.0 - C# 5.0)

The ternary operator works, but if you want even shorter expression working on arbitrary objects you can use:

(myObject ?? "").ToString()

Here is real-life example from my code:

 private HtmlTableCell CreateTableCell(object cellContents)

 {

     return new HtmlTableCell()

     {

         InnerText = (cellContents ?? "").ToString()             

     };

 }

edited Nov 19 '18 at 17:24

answered Jan 20 '15 at 20:01

DKroot

756617

(C# 2.0 - C# 5.0)

The ternary operator works, but if you want even shorter expression working on arbitrary objects you can use:

(myObject ?? "").ToString()

Here is real-life example from my code:

 private HtmlTableCell CreateTableCell(object cellContents)

 {

     return new HtmlTableCell()

     {

         InnerText = (cellContents ?? "").ToString()             

     };

 }

edited Nov 19 '18 at 17:24

answered Jan 20 '15 at 20:01

DKroot

756617

edited Nov 19 '18 at 17:24

answered Jan 20 '15 at 20:01

DKroot

756617

answered Jan 20 '15 at 20:01

DKroot

756617

answered Jan 20 '15 at 20:01

DKroot

756617

One of the outcomes of this code is redundant "".ToString(), moreover (myObject ?? "") will work only if myObject was a string in the first place, making .ToString() even more unnecessary. I think you meant myObject?.ToString() ?? "".
– ensisNoctis
Nov 2 '18 at 20:24

1

@ensisNoctis 1. This was written at the time we had C# 5, which didn't have ?. operator. For C# 6+, I'd use ?.. 2. .ToString() works on objects just fine. I stand by my answer scoped to C# 2 - C# 5: updated to clarify.
– DKroot
Nov 19 '18 at 17:27

Fine with me :)
– ensisNoctis
Nov 20 '18 at 12:05

add a comment |

One of the outcomes of this code is redundant "".ToString(), moreover (myObject ?? "") will work only if myObject was a string in the first place, making .ToString() even more unnecessary. I think you meant myObject?.ToString() ?? "".
– ensisNoctis
Nov 2 '18 at 20:24

1

@ensisNoctis 1. This was written at the time we had C# 5, which didn't have ?. operator. For C# 6+, I'd use ?.. 2. .ToString() works on objects just fine. I stand by my answer scoped to C# 2 - C# 5: updated to clarify.
– DKroot
Nov 19 '18 at 17:27

Fine with me :)
– ensisNoctis
Nov 20 '18 at 12:05

One of the outcomes of this code is redundant "".ToString(), moreover (myObject ?? "") will work only if myObject was a string in the first place, making .ToString() even more unnecessary. I think you meant myObject?.ToString() ?? "".
– ensisNoctis
Nov 2 '18 at 20:24

@ensisNoctis 1. This was written at the time we had C# 5, which didn't have ?. operator. For C# 6+, I'd use ?.. 2. .ToString() works on objects just fine. I stand by my answer scoped to C# 2 - C# 5: updated to clarify.
– DKroot
Nov 19 '18 at 17:27

Fine with me :)
– ensisNoctis
Nov 20 '18 at 12:05

add a comment |

SelectList(blah, "blah", "blah", 

(cu.Customer.CustomerID!=null?cu.Customer.CustomerID.ToString():"")

)

answered Nov 2 '09 at 9:44

Palantir

18k86380

add a comment |

SelectList(blah, "blah", "blah", 

(cu.Customer.CustomerID!=null?cu.Customer.CustomerID.ToString():"")

)

answered Nov 2 '09 at 9:44

Palantir

18k86380

add a comment |

SelectList(blah, "blah", "blah", 

(cu.Customer.CustomerID!=null?cu.Customer.CustomerID.ToString():"")

)

answered Nov 2 '09 at 9:44

Palantir

18k86380

SelectList(blah, "blah", "blah", 

(cu.Customer.CustomerID!=null?cu.Customer.CustomerID.ToString():"")

)

answered Nov 2 '09 at 9:44

Palantir

18k86380

answered Nov 2 '09 at 9:44

Palantir

18k86380

answered Nov 2 '09 at 9:44

Palantir

18k86380

answered Nov 2 '09 at 9:44

Palantir

18k86380

add a comment |

Please don't use this in production :

/// <summary>

/// I most certainly don't recommend using this in production but when one can abuse delegates, one should :)

/// </summary>

public static class DirtyHelpers

{

    public static TVal SafeGet<THolder, TVal>(this THolder holder, Func<TVal> extract) where THolder : class

    {

        return null == holder ? default(TVal) : extract();

    }



    public static void Sample(String name)

    {

        int len = name.SafeGet(()=> name.Length);

    }

}

answered Nov 2 '09 at 11:34

Florian Doyon

3,2181931

add a comment |

Please don't use this in production :

/// <summary>

/// I most certainly don't recommend using this in production but when one can abuse delegates, one should :)

/// </summary>

public static class DirtyHelpers

{

    public static TVal SafeGet<THolder, TVal>(this THolder holder, Func<TVal> extract) where THolder : class

    {

        return null == holder ? default(TVal) : extract();

    }



    public static void Sample(String name)

    {

        int len = name.SafeGet(()=> name.Length);

    }

}

answered Nov 2 '09 at 11:34

Florian Doyon

3,2181931

add a comment |

Please don't use this in production :

/// <summary>

/// I most certainly don't recommend using this in production but when one can abuse delegates, one should :)

/// </summary>

public static class DirtyHelpers

{

    public static TVal SafeGet<THolder, TVal>(this THolder holder, Func<TVal> extract) where THolder : class

    {

        return null == holder ? default(TVal) : extract();

    }



    public static void Sample(String name)

    {

        int len = name.SafeGet(()=> name.Length);

    }

}

answered Nov 2 '09 at 11:34

Florian Doyon

3,2181931

Please don't use this in production :

/// <summary>

/// I most certainly don't recommend using this in production but when one can abuse delegates, one should :)

/// </summary>

public static class DirtyHelpers

{

    public static TVal SafeGet<THolder, TVal>(this THolder holder, Func<TVal> extract) where THolder : class

    {

        return null == holder ? default(TVal) : extract();

    }



    public static void Sample(String name)

    {

        int len = name.SafeGet(()=> name.Length);

    }

}

answered Nov 2 '09 at 11:34

Florian Doyon

3,2181931

answered Nov 2 '09 at 11:34

Florian Doyon

3,2181931

answered Nov 2 '09 at 11:34

Florian Doyon

3,2181931

answered Nov 2 '09 at 11:34

Florian Doyon

3,2181931

add a comment |

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