Dynamic variable in LINQ

Question

I have the following statement in LINQ:

var eventsWithTag = (from occurence in occurrences1
                     join eventTag in serviceContext.CreateQuery("adx_eventtag_event")
                         on occurence.Event.GetAttributeValue<Guid>("adx_eventid") equals eventTag.GetAttributeValue<Guid>("adx_eventid")
                     join tag in serviceContext.CreateQuery("adx_eventtag")
                         on eventTag.GetAttributeValue<Guid>("adx_eventtagid") equals tag.GetAttributeValue<Guid>("adx_eventtagid")
                     where tag.GetAttributeValue<string>("adx_name") == "scotland"
                     select occurence).OrderBy(x => x.Start);

This works fine with the fixed string search of "Scotland" in this instance. However I need to replace that to reflect the current page topic. So essentially I need to replace:

== "scotland"

with:

== getBranch()

where getBranch returns the relevant branch name as a string.

This would lead me to try:

eventsWithTag = (from occurence in occurrences1
join eventTag in serviceContext.CreateQuery("adx_eventtag_event") on occurence.Event.GetAttributeValue<Guid>("adx_eventid") equals eventTag.GetAttributeValue<Guid>("adx_eventid")
join tag in serviceContext.CreateQuery("adx_eventtag") on eventTag.GetAttributeValue<Guid>("adx_eventtagid") equals tag.GetAttributeValue<Guid>("adx_eventtagid")
where tag.GetAttributeValue<string>("adx_name") == getBranch()
select occurence).OrderBy(x => x.Start);

But this doesn't work, and from what little I know of LINQ it is because you can't use variables in this way.

So my question is: How can I use the LINQ query above with a dynamic value for the branch.

Please note: I have seen other posts about this but I evidently don't have the LINQ knowledge to transfer them to my specific needs. Just yet!

Answer 1

Everything looks right so I'd double check your getBranch()...

if this works:

var branch = "scotland";
eventsWithTag = 
    (from occurence in occurrences1
     join eventTag in serviceContext.CreateQuery("adx_eventtag_event") on occurence.Event.GetAttributeValue<Guid>("adx_eventid") equals eventTag.GetAttributeValue<Guid>("adx_eventid")
     join tag in serviceContext.CreateQuery("adx_eventtag") on eventTag.GetAttributeValue<Guid>("adx_eventtagid") equals tag.GetAttributeValue<Guid>("adx_eventtagid")
     where tag.GetAttributeValue<string>("adx_name") == branch 
     select occurence)
    .OrderBy(x => x.Start);

Then p.s.w.g's answer should work, and your issue lies with getBranch returning a value that doesn't match any records...

On a slightly different matter, I'm slightly confused as to why you need to get the actual attributes in your equals statement, because according to this, it should work fine like this:

var branch = "scotland";
eventsWithTag = 
    (from occurence in occurrences1
     join eventTag in serviceContext.CreateQuery("adx_eventtag_event") on occurence.Event["adx_eventid"] equals eventTag["adx_eventid"]
     join tag in serviceContext.CreateQuery("adx_eventtag") on eventTag["adx_eventtagid"] equals tag["adx_eventtagid"]
     where tag["adx_name"] == branch 
     select occurence)
    .OrderBy(x => x.Start);