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Check for specific child record
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#1
 
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Check for specific child record -
12-26-2009
, 10:59 AM
#2
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This is pretty basic, and I've alredy solved it, but I wonder if things are even simpler. In FMP 10, I need to find you whether the present record has a specific keyword assigned, i.e. if there's a child record with a specific foreign key (a different table's key, I'm looking into a join table here). I could create a calculated field that holds this key and use it in a relationship, then I could use IsValid. Without the additional field and relation, I use this: FilterElements ( List ( ChildTable::ForeignKey ) ; // List of all foreign keys "44" ) // the hard coded value I'm looking for = "44¶" // See if this returns right or false (mind the return) Apart from the hard coded value, which could of course be mended - is this the best way to find out? |
particularly if the list of child values might grow long.
Personally, I would create another relationship in the parent file.
This would be a compound relationship. In the parent, create a global
to hold your specific value. Then the relationship becomes:
ValueGlobal = ForeignKey AND
ParentKey = ParentKey
You can instantly check, using IsEmpty(KeyField), whether or not this
child record exists. Don't use IsValid to check for existing records,
that's not what it's intended for and it will fail under certain
circumstances.
The advantage of this, is that if you ever need to check on a different
key word, you can populate the global with whatever you want. And the
IsEmpty test is extremely fast.
--
Lynn Allen
--
www.semiotics.com
Member FBA
FM 10 Certified Developer
#3
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This is pretty basic, and I've alredy solved it, but I wonder if things are even simpler. In FMP 10, I need to find you whether the present record has a specific keyword assigned, i.e. if there's a child record with a specific foreign key (a different table's key, I'm looking into a join table here). I could create a calculated field that holds this key and use it in a relationship, then I could use IsValid. Without the additional field and relation, I use this: FilterElements ( List ( ChildTable::ForeignKey ) ; // List of all foreign keys "44" ) // the hard coded value I'm looking for = "44¶" // See if this returns right or false (mind the return) Apart from the hard coded value, which could of course be mended - is this the best way to find out? -- http://clk.ch |
#4
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What if the value you are looking for comes last in the List? I seem to remember it wouldn't be followed by a pilcrow and the calc would return a false. |
value 45 coming last, the calc returns correct if I for "45¶", but false
if I ask for "45" or 45.
--
http://clk.ch
#5
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This is pretty basic, and I've alredy solved it, but I wonder if things are even simpler. In FMP 10, I need to find you whether the present record has a specific keyword assigned, i.e. if there's a child record with a specific foreign key (a different table's key, I'm looking into a join table here). I could create a calculated field that holds this key and use it in a relationship, then I could use IsValid. Without the additional field and relation, I use this: FilterElements ( List ( ChildTable::ForeignKey ) ; // List of all foreign keys "44" ) // the hard coded value I'm looking for = "44¶" // See if this returns right or false (mind the return) Apart from the hard coded value, which could of course be mended - is this the best way to find out? |
What you have is probably fine. But you can accomplish the same thing
without the custom function, as:
patterncount(
¶ & List ( ChildTable::ForeignKey ) & ¶;
¶ & "44" & ¶
)
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