How to return a value of passed in property of generated object in c#

I have a function that returns a particular type. Ex. FaxFile. In that object there are several different formats to download ex: PDF, LargeJpg, SmallJpg, etc.

I can call the download a pdf like this.

public FaxFile DownloadFaxPDFById(int faxId)

{

    return DownloadFaxById(faxId).Pdf;

}

What I am wanting to do is be able to pass in the property of the object ex. LargeJpg Format to download.

Sudo Code

public FaxFile DownloadFaxTypeById(int faxId, property)

{

   return DownloadFaxById(faxId).property;

}

How do I do this?

asked Jan 2 at 14:43

Demodave

3,52642942

why not use use switch case based on property?

– Karthik Ganesan
Jan 2 at 14:45

You can't use delegates for this, but you can use lambdas.

– Yola
Jan 2 at 14:46

2

@Yola Lambdas are one of the ways of creating delegates. It's literally impossible to use lambdas without using delegates.

– Servy
Jan 2 at 14:51

1

What is 'Sudo Code'? Only executable by admins? :s

– nilsK
Jan 2 at 15:00

Are there only FaxFile or do you have also something like PDFFaxFile or LargeJpgFaxFile?

– nosale
Jan 2 at 15:00

|
show 1 more comment

I have a function that returns a particular type. Ex. FaxFile. In that object there are several different formats to download ex: PDF, LargeJpg, SmallJpg, etc.

I can call the download a pdf like this.

public FaxFile DownloadFaxPDFById(int faxId)

{

    return DownloadFaxById(faxId).Pdf;

}

What I am wanting to do is be able to pass in the property of the object ex. LargeJpg Format to download.

Sudo Code

public FaxFile DownloadFaxTypeById(int faxId, property)

{

   return DownloadFaxById(faxId).property;

}

How do I do this?

asked Jan 2 at 14:43

Demodave

3,52642942

why not use use switch case based on property?

– Karthik Ganesan
Jan 2 at 14:45

You can't use delegates for this, but you can use lambdas.

– Yola
Jan 2 at 14:46

2

@Yola Lambdas are one of the ways of creating delegates. It's literally impossible to use lambdas without using delegates.

– Servy
Jan 2 at 14:51

1

What is 'Sudo Code'? Only executable by admins? :s

– nilsK
Jan 2 at 15:00

Are there only FaxFile or do you have also something like PDFFaxFile or LargeJpgFaxFile?

– nosale
Jan 2 at 15:00

|
show 1 more comment

I have a function that returns a particular type. Ex. FaxFile. In that object there are several different formats to download ex: PDF, LargeJpg, SmallJpg, etc.

I can call the download a pdf like this.

public FaxFile DownloadFaxPDFById(int faxId)

{

    return DownloadFaxById(faxId).Pdf;

}

What I am wanting to do is be able to pass in the property of the object ex. LargeJpg Format to download.

Sudo Code

public FaxFile DownloadFaxTypeById(int faxId, property)

{

   return DownloadFaxById(faxId).property;

}

How do I do this?

asked Jan 2 at 14:43

Demodave

3,52642942

I have a function that returns a particular type. Ex. FaxFile. In that object there are several different formats to download ex: PDF, LargeJpg, SmallJpg, etc.

I can call the download a pdf like this.

public FaxFile DownloadFaxPDFById(int faxId)

{

    return DownloadFaxById(faxId).Pdf;

}

What I am wanting to do is be able to pass in the property of the object ex. LargeJpg Format to download.

Sudo Code

public FaxFile DownloadFaxTypeById(int faxId, property)

{

   return DownloadFaxById(faxId).property;

}

How do I do this?

asked Jan 2 at 14:43

Demodave

3,52642942

asked Jan 2 at 14:43

Demodave

3,52642942

asked Jan 2 at 14:43

Demodave

3,52642942

asked Jan 2 at 14:43

Demodave

3,52642942

asked Jan 2 at 14:43

Demodave

3,52642942

why not use use switch case based on property?

– Karthik Ganesan
Jan 2 at 14:45

You can't use delegates for this, but you can use lambdas.

– Yola
Jan 2 at 14:46

2

@Yola Lambdas are one of the ways of creating delegates. It's literally impossible to use lambdas without using delegates.

– Servy
Jan 2 at 14:51

1

What is 'Sudo Code'? Only executable by admins? :s

– nilsK
Jan 2 at 15:00

Are there only FaxFile or do you have also something like PDFFaxFile or LargeJpgFaxFile?

– nosale
Jan 2 at 15:00

|
show 1 more comment

why not use use switch case based on property?

– Karthik Ganesan
Jan 2 at 14:45

You can't use delegates for this, but you can use lambdas.

– Yola
Jan 2 at 14:46

2

@Yola Lambdas are one of the ways of creating delegates. It's literally impossible to use lambdas without using delegates.

– Servy
Jan 2 at 14:51

1

What is 'Sudo Code'? Only executable by admins? :s

– nilsK
Jan 2 at 15:00

Are there only FaxFile or do you have also something like PDFFaxFile or LargeJpgFaxFile?

– nosale
Jan 2 at 15:00

why not use use switch case based on property?

– Karthik Ganesan
Jan 2 at 14:45

You can't use delegates for this, but you can use lambdas.

– Yola
Jan 2 at 14:46

@Yola Lambdas are one of the ways of creating delegates. It's literally impossible to use lambdas without using delegates.

– Servy
Jan 2 at 14:51

What is 'Sudo Code'? Only executable by admins? :s

– nilsK
Jan 2 at 15:00

Are there only FaxFile or do you have also something like PDFFaxFile or LargeJpgFaxFile?

– nosale
Jan 2 at 15:00

|
show 1 more comment

5 Answers
5

active

oldest

votes

I would recommend to create an enum for this and pass it to your function.

Inside your function simple use switch.

This means more programming, but the usage of your function is much clearer.

This has also the benefit that you later can change the code how you obtain each format without taking care of the consumer of your function.

enum FaxFileType

{

    PDF,

    LargeJpg,

    SmallJpg,

    ...

}

public FaxFile DownloadFaxById(int faxId, FaxFileType faxFileType)

{

    switch (faxFileType)

    {

        case FaxFileType.PDF:

            return DownloadFaxById(faxId).PDF;

        case FaxFileType.LargeJpg:

            return DownloadFaxById(faxId).LargeJpg;

        case FaxFileType.SmallJpg:

            return DownloadFaxById(faxId).SmallJpg;

        ...

        default:

            throw new NotSupportedException();

    }

}

edited Jan 2 at 15:34

answered Jan 2 at 15:17

nosale

672212

This one appears to be the simplest solution. As this library I am using I don't think will change I should choose this.

– Demodave
Jan 4 at 13:47

add a comment |

you can use reflection.

var resultObj = DownloadFaxById(faxId);

var result = resultObj.GetType().GetProperty("<propertyName>").GetValue(resultObj);

please note that you need to cast result to appropriate object

answered Jan 2 at 14:50

Derviş Kayımbaşıoğlu

15.6k22042

I would possibly choose this one if the object I had would changed

– Demodave
Jan 4 at 13:48

add a comment |

You don't want to do this at the first place. Just use DownloadFaxById(faxId).Pdf/LargeJpg/...; in the call place or, if you don't want to expose class returned by DownloadFaxById either subclass or use aggregation and expose Pdf, LargeJpg, ... in this new class.

answered Jan 2 at 15:09

Yola

11.3k64672

add a comment |

Another way of doing this besides those already posted as answers is to use lambda expressions. Not sure what's the type of the downloaded object, so replace DownloadedObjectType with your own.

public FaxFile DownloadFaxTypeById(int faxId, Expression<Func<DownloadedObjectType, FaxFile>> expression) {



    if (!(expression.Body is MemberExpression)) {

        throw new ArgumentException("Invalid expression");

    }



    return expression.Compile().Invoke(DownloadFaxById(faxId));

}

You then call it as

DownloadFaxTypeById(faxId, obj => obj.Pdf)

However looks much uglier than simply calling

DownloadFaxTypeById(faxId).Pdf

Except for maybe providing you some control over what properties can the caller retrieve, limiting them to that specific return type and only those that are actually available for that type. This way for a subset of possible errors (like referencing non-existing property) you get compile time errors rather than all runtime as in cases using reflection.

edited Jan 2 at 15:16

answered Jan 2 at 14:57

Imantas

1,103918

1

I agree that DownloadFaxTypeById(faxId).Pdf is much simpler, would interesting to see why this is not a viable solution.

– Scrobi
Jan 2 at 15:06

I started down this path, but I too thought it had to be simpler

– Demodave
Jan 4 at 13:49

add a comment |

You should probably just use a switch statement for each format type you support from an enum. However if you really want to use reflection, you can so it as follows:

void Main()

{

    var foo = new Foo();



    foo.GetType().GetProperty("MyProp").SetValue(foo, "Test");

    var val = foo.GetType().GetProperty("MyProp").GetValue(foo);



    Console.WriteLine(val);

}



public class Foo

{

    public String MyProp { get; set; }

}

answered Jan 2 at 14:51

Carlo Bos

748513

add a comment |

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5 Answers
5

active

oldest

votes

5 Answers
5

active

oldest

votes

enum FaxFileType

{

    PDF,

    LargeJpg,

    SmallJpg,

    ...

}

public FaxFile DownloadFaxById(int faxId, FaxFileType faxFileType)

{

    switch (faxFileType)

    {

        case FaxFileType.PDF:

            return DownloadFaxById(faxId).PDF;

        case FaxFileType.LargeJpg:

            return DownloadFaxById(faxId).LargeJpg;

        case FaxFileType.SmallJpg:

            return DownloadFaxById(faxId).SmallJpg;

        ...

        default:

            throw new NotSupportedException();

    }

}

edited Jan 2 at 15:34

answered Jan 2 at 15:17

nosale

672212

This one appears to be the simplest solution. As this library I am using I don't think will change I should choose this.

– Demodave
Jan 4 at 13:47

add a comment |

enum FaxFileType

{

    PDF,

    LargeJpg,

    SmallJpg,

    ...

}

public FaxFile DownloadFaxById(int faxId, FaxFileType faxFileType)

{

    switch (faxFileType)

    {

        case FaxFileType.PDF:

            return DownloadFaxById(faxId).PDF;

        case FaxFileType.LargeJpg:

            return DownloadFaxById(faxId).LargeJpg;

        case FaxFileType.SmallJpg:

            return DownloadFaxById(faxId).SmallJpg;

        ...

        default:

            throw new NotSupportedException();

    }

}

edited Jan 2 at 15:34

answered Jan 2 at 15:17

nosale

672212

This one appears to be the simplest solution. As this library I am using I don't think will change I should choose this.

– Demodave
Jan 4 at 13:47

add a comment |

enum FaxFileType

{

    PDF,

    LargeJpg,

    SmallJpg,

    ...

}

public FaxFile DownloadFaxById(int faxId, FaxFileType faxFileType)

{

    switch (faxFileType)

    {

        case FaxFileType.PDF:

            return DownloadFaxById(faxId).PDF;

        case FaxFileType.LargeJpg:

            return DownloadFaxById(faxId).LargeJpg;

        case FaxFileType.SmallJpg:

            return DownloadFaxById(faxId).SmallJpg;

        ...

        default:

            throw new NotSupportedException();

    }

}

edited Jan 2 at 15:34

answered Jan 2 at 15:17

nosale

672212

enum FaxFileType

{

    PDF,

    LargeJpg,

    SmallJpg,

    ...

}

public FaxFile DownloadFaxById(int faxId, FaxFileType faxFileType)

{

    switch (faxFileType)

    {

        case FaxFileType.PDF:

            return DownloadFaxById(faxId).PDF;

        case FaxFileType.LargeJpg:

            return DownloadFaxById(faxId).LargeJpg;

        case FaxFileType.SmallJpg:

            return DownloadFaxById(faxId).SmallJpg;

        ...

        default:

            throw new NotSupportedException();

    }

}

edited Jan 2 at 15:34

answered Jan 2 at 15:17

nosale

672212

edited Jan 2 at 15:34

answered Jan 2 at 15:17

nosale

672212

answered Jan 2 at 15:17

nosale

672212

answered Jan 2 at 15:17

nosale

672212

This one appears to be the simplest solution. As this library I am using I don't think will change I should choose this.

– Demodave
Jan 4 at 13:47

add a comment |

This one appears to be the simplest solution. As this library I am using I don't think will change I should choose this.

– Demodave
Jan 4 at 13:47

This one appears to be the simplest solution. As this library I am using I don't think will change I should choose this.

– Demodave
Jan 4 at 13:47

add a comment |

you can use reflection.

var resultObj = DownloadFaxById(faxId);

var result = resultObj.GetType().GetProperty("<propertyName>").GetValue(resultObj);

please note that you need to cast result to appropriate object

answered Jan 2 at 14:50

Derviş Kayımbaşıoğlu

15.6k22042

I would possibly choose this one if the object I had would changed

– Demodave
Jan 4 at 13:48

add a comment |

you can use reflection.

var resultObj = DownloadFaxById(faxId);

var result = resultObj.GetType().GetProperty("<propertyName>").GetValue(resultObj);

please note that you need to cast result to appropriate object

answered Jan 2 at 14:50

Derviş Kayımbaşıoğlu

15.6k22042

I would possibly choose this one if the object I had would changed

– Demodave
Jan 4 at 13:48

add a comment |

you can use reflection.

var resultObj = DownloadFaxById(faxId);

var result = resultObj.GetType().GetProperty("<propertyName>").GetValue(resultObj);

please note that you need to cast result to appropriate object

answered Jan 2 at 14:50

Derviş Kayımbaşıoğlu

15.6k22042

you can use reflection.

var resultObj = DownloadFaxById(faxId);

var result = resultObj.GetType().GetProperty("<propertyName>").GetValue(resultObj);

please note that you need to cast result to appropriate object

answered Jan 2 at 14:50

Derviş Kayımbaşıoğlu

15.6k22042

answered Jan 2 at 14:50

Derviş Kayımbaşıoğlu

15.6k22042

answered Jan 2 at 14:50

Derviş Kayımbaşıoğlu

15.6k22042

answered Jan 2 at 14:50

Derviş Kayımbaşıoğlu

15.6k22042

I would possibly choose this one if the object I had would changed

– Demodave
Jan 4 at 13:48

add a comment |

I would possibly choose this one if the object I had would changed

– Demodave
Jan 4 at 13:48

I would possibly choose this one if the object I had would changed

– Demodave
Jan 4 at 13:48

add a comment |

answered Jan 2 at 15:09

Yola

11.3k64672

add a comment |

answered Jan 2 at 15:09

Yola

11.3k64672

add a comment |

answered Jan 2 at 15:09

Yola

11.3k64672

answered Jan 2 at 15:09

Yola

11.3k64672

answered Jan 2 at 15:09

Yola

11.3k64672

answered Jan 2 at 15:09

Yola

11.3k64672

answered Jan 2 at 15:09

Yola

11.3k64672

add a comment |

Another way of doing this besides those already posted as answers is to use lambda expressions. Not sure what's the type of the downloaded object, so replace DownloadedObjectType with your own.

public FaxFile DownloadFaxTypeById(int faxId, Expression<Func<DownloadedObjectType, FaxFile>> expression) {



    if (!(expression.Body is MemberExpression)) {

        throw new ArgumentException("Invalid expression");

    }



    return expression.Compile().Invoke(DownloadFaxById(faxId));

}

You then call it as

DownloadFaxTypeById(faxId, obj => obj.Pdf)

However looks much uglier than simply calling

DownloadFaxTypeById(faxId).Pdf

edited Jan 2 at 15:16

answered Jan 2 at 14:57

Imantas

1,103918

1

I agree that DownloadFaxTypeById(faxId).Pdf is much simpler, would interesting to see why this is not a viable solution.

– Scrobi
Jan 2 at 15:06

I started down this path, but I too thought it had to be simpler

– Demodave
Jan 4 at 13:49

add a comment |

Another way of doing this besides those already posted as answers is to use lambda expressions. Not sure what's the type of the downloaded object, so replace DownloadedObjectType with your own.

public FaxFile DownloadFaxTypeById(int faxId, Expression<Func<DownloadedObjectType, FaxFile>> expression) {



    if (!(expression.Body is MemberExpression)) {

        throw new ArgumentException("Invalid expression");

    }



    return expression.Compile().Invoke(DownloadFaxById(faxId));

}

You then call it as

DownloadFaxTypeById(faxId, obj => obj.Pdf)

However looks much uglier than simply calling

DownloadFaxTypeById(faxId).Pdf

edited Jan 2 at 15:16

answered Jan 2 at 14:57

Imantas

1,103918

1

I agree that DownloadFaxTypeById(faxId).Pdf is much simpler, would interesting to see why this is not a viable solution.

– Scrobi
Jan 2 at 15:06

I started down this path, but I too thought it had to be simpler

– Demodave
Jan 4 at 13:49

add a comment |

Another way of doing this besides those already posted as answers is to use lambda expressions. Not sure what's the type of the downloaded object, so replace DownloadedObjectType with your own.

public FaxFile DownloadFaxTypeById(int faxId, Expression<Func<DownloadedObjectType, FaxFile>> expression) {



    if (!(expression.Body is MemberExpression)) {

        throw new ArgumentException("Invalid expression");

    }



    return expression.Compile().Invoke(DownloadFaxById(faxId));

}

You then call it as

DownloadFaxTypeById(faxId, obj => obj.Pdf)

However looks much uglier than simply calling

DownloadFaxTypeById(faxId).Pdf

edited Jan 2 at 15:16

answered Jan 2 at 14:57

Imantas

1,103918

Another way of doing this besides those already posted as answers is to use lambda expressions. Not sure what's the type of the downloaded object, so replace DownloadedObjectType with your own.

public FaxFile DownloadFaxTypeById(int faxId, Expression<Func<DownloadedObjectType, FaxFile>> expression) {



    if (!(expression.Body is MemberExpression)) {

        throw new ArgumentException("Invalid expression");

    }



    return expression.Compile().Invoke(DownloadFaxById(faxId));

}

You then call it as

DownloadFaxTypeById(faxId, obj => obj.Pdf)

However looks much uglier than simply calling

DownloadFaxTypeById(faxId).Pdf

edited Jan 2 at 15:16

answered Jan 2 at 14:57

Imantas

1,103918

edited Jan 2 at 15:16

answered Jan 2 at 14:57

Imantas

1,103918

answered Jan 2 at 14:57

Imantas

1,103918

answered Jan 2 at 14:57

Imantas

1,103918

1

I agree that DownloadFaxTypeById(faxId).Pdf is much simpler, would interesting to see why this is not a viable solution.

– Scrobi
Jan 2 at 15:06

I started down this path, but I too thought it had to be simpler

– Demodave
Jan 4 at 13:49

add a comment |

1

I agree that DownloadFaxTypeById(faxId).Pdf is much simpler, would interesting to see why this is not a viable solution.

– Scrobi
Jan 2 at 15:06

I started down this path, but I too thought it had to be simpler

– Demodave
Jan 4 at 13:49

I agree that DownloadFaxTypeById(faxId).Pdf is much simpler, would interesting to see why this is not a viable solution.

– Scrobi
Jan 2 at 15:06

I started down this path, but I too thought it had to be simpler

– Demodave
Jan 4 at 13:49

add a comment |

You should probably just use a switch statement for each format type you support from an enum. However if you really want to use reflection, you can so it as follows:

void Main()

{

    var foo = new Foo();



    foo.GetType().GetProperty("MyProp").SetValue(foo, "Test");

    var val = foo.GetType().GetProperty("MyProp").GetValue(foo);



    Console.WriteLine(val);

}



public class Foo

{

    public String MyProp { get; set; }

}

answered Jan 2 at 14:51

Carlo Bos

748513

add a comment |

You should probably just use a switch statement for each format type you support from an enum. However if you really want to use reflection, you can so it as follows:

void Main()

{

    var foo = new Foo();



    foo.GetType().GetProperty("MyProp").SetValue(foo, "Test");

    var val = foo.GetType().GetProperty("MyProp").GetValue(foo);



    Console.WriteLine(val);

}



public class Foo

{

    public String MyProp { get; set; }

}

answered Jan 2 at 14:51

Carlo Bos

748513

add a comment |

You should probably just use a switch statement for each format type you support from an enum. However if you really want to use reflection, you can so it as follows:

void Main()

{

    var foo = new Foo();



    foo.GetType().GetProperty("MyProp").SetValue(foo, "Test");

    var val = foo.GetType().GetProperty("MyProp").GetValue(foo);



    Console.WriteLine(val);

}



public class Foo

{

    public String MyProp { get; set; }

}

answered Jan 2 at 14:51

Carlo Bos

748513

You should probably just use a switch statement for each format type you support from an enum. However if you really want to use reflection, you can so it as follows:

void Main()

{

    var foo = new Foo();



    foo.GetType().GetProperty("MyProp").SetValue(foo, "Test");

    var val = foo.GetType().GetProperty("MyProp").GetValue(foo);



    Console.WriteLine(val);

}



public class Foo

{

    public String MyProp { get; set; }

}

answered Jan 2 at 14:51

Carlo Bos

748513

answered Jan 2 at 14:51

Carlo Bos

748513

answered Jan 2 at 14:51

Carlo Bos

748513

answered Jan 2 at 14:51

Carlo Bos

748513

add a comment |

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