Lambda "if" statement?

Question

I have 2 objects, both of which I want to convert to dictionarys. I use toDictionary<>().

The lambda expression for one object to get the key is (i => i.name). For the other, it's (i => i.inner.name). In the second one, i.name doesn't exist. i.inner.name ALWAYS exists if i.name doesn't.

Is there a lambda expression I can use to combine these two? Basically to read as:

"if i.name exists then set id to i.name, else set id to i.inner.name".

Many thanks.

Update

When I say "don't exist", I mean the objects don't actually have the properties, not that the properties are just null.

If you say that the properties don't exist, do you mean that the objects actually don't have the properties, or that the properties are just null? — OregonGhost
– OregonGhost, Commented Mar 19, 2010 at 11:00
So then these two types are two completely unrelated types then? — shf301
– shf301, Commented Mar 19, 2010 at 11:11
@shf301 yes. However, all of them either have a name property, or a object.name property of type string. — AndrewC
– AndrewC, Commented Mar 19, 2010 at 11:31

LukeH · Accepted Answer · 2010-03-19 16:12:33Z

14

If these are two distinct (reference) types then you can test them using the is or as keywords:

i => {
         var x = i as TypeThatHasNameProperty;
         return (x != null) ? x.name : i.inner.name;
     }

If you can't test for specific types then you can use reflection to test for the name property itself:

i => {
         var pi = i.GetType().GetProperty("name");
         return (pi != null) ? pi.GetValue(i, null) : i.inner.name;
     }

edited Mar 19, 2010 at 16:12

answered Mar 19, 2010 at 11:07

LukeH

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4 Comments

dtb Over a year ago

Don't you need to cast i to TypeThatHasNameProperty before you can access the Name property?

LukeH Over a year ago

@dtb: Probably, I suppose it depends on what the rest of the OP's code looks like. (But it wouldn't do any harm to make the cast anyway, although in my example code I think using as is probably more appropriate than a plain cast.)

Alex Gordon Over a year ago

great job on this answer

Jessica Over a year ago

This is a more appropriate answer

Thomas · Accepted Answer · 2010-03-19 10:59:19Z

7

Yes, the conditional operator ("ternary operator") does what you want:

(i => i.name != null ? i.name : i.inner.name)

Assuming, of course, that you can detect the "existence" of the name by checking for null.

Edit: In that case, Kirschstein's answer is better, of course.

answered Mar 19, 2010 at 10:59

Thomas

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1 Comment

AndrewC Over a year ago

What I meant is, i.name doesn't exist at all. The property name isn't there. I can't use null. Apologies if I made that unclear.

Sekhat · Accepted Answer · 2010-03-19 12:06:43Z

4

Why don't you give each object a ToDictionary method of their own, as they obviously have their own behaviours in this case.

If you can't add to the objects, because you don't own them, you can always write extension methods for them.

Any reason your trying to force feed them into one "common" function?

edited Mar 19, 2010 at 12:06

answered Mar 19, 2010 at 11:12

Sekhat

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2 Comments

ZombieSheep Over a year ago

Maybe overriding ToString() would be the best behavioural choice for these objects. Of course, that depends on whether you rely on other behaviour in ToString() elsewhere...

AndrewC Over a year ago

@Sekhat I was just seeing if I could combine it into one function as I need to do it quite a few times. For the sake of tidiness.

ZombieSheep · Accepted Answer · 2010-03-19 11:00:02Z

0

something along the lines of

collection1.ForEach(i => myDictionary.Add((i.name.length == 0 ? i.inner.name : i.name),value);

(untested) should do the trick if i.name is not null (an empty string), or

collection1.ForEach(i => myDictionary.Add((i.name ?? i.inner.name),value);

(also untested)

answered Mar 19, 2010 at 11:00

ZombieSheep

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Comments

Yelo · Accepted Answer · 2019-06-07 09:49:59Z

-1

as an inline if query I would use a ternary operator, so:

(i.name != null ? set id to i.name : set id to i.inner.name)

answered Jun 7, 2019 at 9:49

Yelo

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