Linq. Join.

[shapper]

Hello,

I have a list named Form which is a List(Of Tag) where Tag is an
object with two properties: ID and Name.

I want to define a variable named Check that:

1. Is True if all Tags in Form are found in database.Tags given each
Tag Name

2. Is False if there is at least one tag in Form that, given its name,
is not present in Database.Tags.

How can I do this?

Thanks,
Miguel

[shapper]

On Aug 22, 6:34*pm, shapper <[e-mail]:

Hello,

I have a list named Form which is a List(Of Tag) where Tag is an
object with two properties: ID and Name.

I want to define a variable named Check that:

1. Is True if all Tags in Form are found in database.Tags given each
Tag Name

2. Is False if there is at least one tag in Form that, given its name,
is not present in Database.Tags.

How can I do this?

Thanks,
Miguel

I have the following:

bool verify = (from t in database.Tags
join f in Form on t.Name equals f.Name
select t).Any();

But, if I am not wrong, this checks if Any of the tags in Form exist
in database.
But I want to check if all exist.

Does anyone knows what should I do?

Thanks,
Miguel

[Peter Duniho]

On Fri, 22 Aug 2008 10:52:31 -0700, shapper <md*****@gmail.comwrote:

I have the following:

bool verify = (from t in database.Tags
join f in Form on t.Name equals f.Name
select t).Any();

But, if I am not wrong, this checks if Any of the tags in Form exist
in database.
But I want to check if all exist.

Does anyone knows what should I do?

It seems to me that you could either:

-- reverse the join so that the result includes only those Tags in
your Form that _don't_ appear in the database (a non-empty result
indicates your "false" condition)
-- compare the Count of the results to the Count of the Form; if they
are equal, then all Tags matched, otherwise at least one didn't

Pete

[shapper]

On Aug 22, 7:05*pm, "Peter Duniho" <[e-mail]>
wrote:

On Fri, 22 Aug 2008 10:52:31 -0700, shapper <[e-mail]:

I have the following:

* * * bool verify = (from t in database.Tags
* * * * * * * * * * * * *join f in Form on t.Name equals f.Name
* * * * * * * * * * * * *select t).Any();

But, if I am not wrong, this checks if Any of the tags in Form exist
in database.
But I want to check if all exist.

Does anyone knows what should I do?

It seems to me that you could either:

* * *-- reverse the join so that the result includes only those Tags in *
your Form that _don't_ appear in the database (a non-empty result *
indicates your "false" condition)
* * *-- compare the Count of the results to the Count of the Form; if they *
are equal, then all Tags matched, otherwise at least one didn't

Pete

I am a little bit confuse. You mean:

bool verify = (from l in list
join t in database.Tags on l.Name equals t.Name
select l).Any();

It is not working.

Am I doing something wrong?

Thanks,
Miguel

[Peter Duniho]

On Fri, 22 Aug 2008 14:05:10 -0700, shapper <md*****@gmail.comwrote:

I am a little bit confuse. You mean:

bool verify = (from l in list
join t in database.Tags on l.Name equals t.Name
select l).Any();

Sorry, no...that's not what I mean. I didn't intend for you to take the
word "reverse" so literally. I just mean to do a different query that
excludes matching records instead of includes them. I'm not a database
expert, and "join" is probably technically the wrong word to use. You
probably wouldn't even use the "join" keyword in the LINQ query. But I
don't know the jargon, so I didn't have any better way to describe it.

That said, the second option should work fine, I'd think.

Pete