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Dynamic sorting of lists
Dear $all,
I am writing a method to sort lists, where I pass the the fields to be sorted as row(‘fieldname1′,’fieldname2′,…,’fieldnameN’). How do I build the $sort parameters in order to make it work? This, and MANY other attempts did not work (however, it does some sorting, but I have not understanding the logic of it…):
Calculate llList as $cinst
For liCurrentCol from 1 to prSortByFields.$colcount
Calculate lcSortField as prSortByFields.[liCurrentCol]
Calculate lcSortOrder as con(lcSortOrder,llList.$sqlclassname,'.',lcSortField,',kFalse,')
End For
Calculate lcSortOrder as left(lcSortOrder,len(lcSortOrder)-1)
Do llList.$sort(lcSortOrder)
Thanks in advance
Uwe
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4 Replies
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Hi Uwe,
The $sort requires a reference to the list column, not just the name of the list column. Only if using a list that is defined from other variables it might work like this.
Do the normal syntax would be something like this:
Do myList.$sort($ref.myColumn,kFalse,$ref.anotherColumn,kFalse)
or
Do myList.$sort(myList.myColumn,kFalse,myList.anotherColumn,kFalse)
I personally prefer $ref.
This said you would be able to create your string including the “$ref.” part. But when executing you would need to make sure that the string is executed.
Not tested though but I guess something of this might work:
Do myList.$search([mySearchArgument])
or maybe
Do myList.$search(eval(mySearchArgument))
Hope this helps.
Best,
Andreas
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Uwe,
On the other hand instead of using the real column names you could also do something like this. So if you know the list has two columns you could do this:
Do myList.$search($ref.c1,kFalse,$ref.c2,kFalse)
Best,
Andreas
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Hi Andreas,
Thanks for your prompt response.
I will try the [] and eval – approach, but your second answer does allow for the dynamic aspect of my intended method: I do not know how many sort column there will be, so a static approach will not work.
Right now, I am trying to work around the problem (very unelegantly) with:
Switch prSortByFields.$colcount ## depending on no of sort cols..
Case 1
Do llList.$sort($ref.[prSortByFields.1],kFalse) ## ...set up the $sort - params
Case 2
Do llList.$sort($ref.[prSortByFields.1],kFalse,$ref.[prSortByFields.2],kFalse)
Case 3
Do llList.$sort($ref.[prSortByFields.1],kFalse,$ref.[prSortByFields.2],kFalse,$ref.[prSortByFields.3],kFalse)
Case 4
Do llList.$sort($ref.[prSortByFields.1],kFalse,$ref.[prSortByFields.2],kFalse,$ref.[prSortByFields.3],kFalse,$ref.[prSortByFields.4],kFalse)
Case 5
Do llList.$sort($ref.[prSortByFields.1],kFalse,$ref.[prSortByFields.2],kFalse,$ref.[prSortByFields.3],kFalse,$ref.[prSortByFields.4],kFalse,$ref.[prSortByFields.5],kFalse)
Default
#0 or more than 5 sort coloumns: do nothing, as yet
End Switch
But I’ll try with [] and eval()!
Best regards
Uwe -
[], eval() and evalf() did not work 😳, but my unelegant spaghetti code did work.
I would still favour a more elegant solution than switch casing, because this dynamic problem not only applies to $sort, but everywhere where $ref is use in the parameter of a method, eg $search() etc
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