This is for the Wizards of Arrays among you.
All these years I’ve done most of my list processing with “repeat for each line
x of some list”
Where the lines are tab delimited data or | pipe delimited. My baby talk
stepping through these and parsing for items on the way thru works. It’s also
very easy to read and plenty fast enough even if you get to 10,000 plus lines..
Slowly I’m getting to grips with arrays and using them whenever I can wrap my
head around the algorithm. My current use case has me stumped. The number of
lines of the list is small, and I could use my old parsing methods but I would
like to see how arrays might be used to better effect. I’m sure this has been
addressed many times by the Wizards of the Arrays
More and more we are accessing web databases where the significant data is in a
relational table.
E. g. table categories: category_id | name
category_tree parent_id | child_id
I see these little “mysterious” relational tables everywhere.. In Word Press,
XOOPS modules etc. I say mysterious because they often consist of just two
columns with the primary ID’s from one or two other tables.
The core of the challenge lies in the fact that if you take the first item as a
“key” it won’t work because it may be used multiple times and if you just
split by cr and tab… something like the following:
Eg (tab separated here]
Categories
138 Fruit
107 Vegetables
111 Dead Animals
43 Apples
Etc
Category tree: this is the relational table:
12 6
138 43
107 139
99 6
88 134
26 6
55 6
108 6
81 2
63 6
138 131
130 131
45 6
91 131
37 6
75 139
107 131
127 131
11 131
138 6
111 106
Etc. means you will end up with aCategoryParents[“138”] = 6 when in fact
there are three “children” of parent ID 138 in the list. So you cannot really
set “138” as a key because it has multiple values that need to be addressed and
parseable. Now I know I could go diving into the world of SQL queries and get
the server API’s to run those against the database, but I want to reduce the
server side processing requirements/connections for the client side app and we
may even store this in customProps so they are accessible off line and the
simplest thing, server side, is to just get the API to dump the tables to tab
delimited lists and ship that to the client… These lists are small -- 130 to
500 lines at most. Select * from table is nearly instantaneous… Then do the
work with LC list tools and arrays. This keeps my API’s simple and keeps the
app code with the app. What I want to able to do is quickly shift between data
sets like this
Parent | Children
138 | 43,131,6
The user will be clicking on the human readable Parent lists like
Fruit
Vegetables
Dead Animals
They click on the list on the left and on the right show, e.g.
Fruit apples
Pears
Grapes
Then
Dead Animals Pork chops
Salmon
Chicken
I wonder how this might be facilitated with arrays? But I can’t wrap my head
around the core problem: how to split a list where the first element may be
repeated throughout with different values. And if there is a way…with nested
arrays... how to query that array to get the data back out?
OK… I’m off to write my old methods… for now..
repeat for each line x in tParentChildList
# parse and output the items here… usually takes a number of lines,
# setting flags and little local vars along the way
End repeat
It will be interesting if these introduce delays in the UI. I’m sure that
arrays is probably a better way to go…but beyond me…if this is something you
have solved. Can you share?
Thanks!
BR
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