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[REBOL] Re: REBOL Relational Object-oriented Database

From: gjones05:mail:orion at: 26-Jun-2001 8:08

Hi, Louis, It looks like your database is coming along famously. LT> The latest version of my program is below. I am having problems in the LT> following areas. LT> 1. The edit-data function isn't working---possibly because I don't LT> understand how to use it. Possibly because I didn't explain it very well. :-) LT> 2. The kbhit function usually works, but sometimes gives the following error: LT> Enter the # of Choice (or ESC to Exit): ** Script Error: choice has no value LT> ** Where: forever LT> ** Near: choice = kbhit LT> if choice LT> Usually I get that error when the program first starts. If I then type LT> kbhit from the console, and hit a key, it will work properly, and I can LT> restart the program and it will work. Adding a default choice of 0 seemed to fix the problem. LT> 3. Print Reports does print the data to the screen, but it also causes LT> loss of all the data! For your own testing purposes, after typing in some LT> data save it to a CSV file using choice 6 from the main menu. Then if you LT> lose it using choice 5 you can then read it back in using choice 7. Forskip has the "side effect" of causing the series pointer to point to the tail. One must explicitly reset the series pointer back to the head of the series. Here is what I've come up with this morning. I made a number of changes that are dcumented within the code below. I think that it is getting close. Good work, Louis, I think the kbhit makes it easier to use! --Scott Jones ;;;;;;;;;;;;;;;;;;;;;;;;; REBOL [ Title: "REBOL Relational Object DBMS" Date: "26 June 2001" Version: 0.3 File: %db.r Author: "Carl Sassenrath and Louis A. Turk" Email: [louisaturk--eudoramail--com] Language: 'English Purpose: "A simple but complete relational object-oriented dbms." Comments: {Carl Sessenrath made these object oriented database management system functions as an example to teach me, Louis A. Turk, how to program an object database myself. Many thanks Carl! The comments about features below are mostly Carl's, edited by Louis for this script header. Features: 1. The db works from memory. Load-data brings it into memory where the find, remove and other functions operate on it. So, you have to load it first, or at least insert-data a few times to create some data records. 2. You can expand or reduce the record definition without corrupting or affecting the database. 3. If you expect to grow this database to a large size, you will want to MAKE HASH! the database when you load it. make the hash after the database is created (after the foreach loop). database: make hash! database But, don't worry about that until your database gets big. For a few hundred names, you don't need it. 4. The functions work like this: rec: find-data [bob--example--com] print rec/name print rec/phone etc. remove-data [bob--example--com] save-data ; write back to disk insert-data [kit--example--com] "Kitty Carson" none http:/www.a.com save-data ; write back to disk 5. You can use NONE for any missing value above. You don't need to do the save-data each time... but you must do it sooner or later. 6. The data is organized (keyed) by email. To change an email address, but keep the rest of the record intact, use the function change-data. Let's examine change-data: change-data: func [email-old email-new /local record] [ record: find database email-old if none? record [alert reform ["Missing record:" email-old] exit] insert clear first record email-new ; see note below ] Note: This is subtle, so should be noted... I'm clearing out the actual memory string for the old email, then inserting the new string into it. Also, this string is shared. It is used both in the database block (as the key) and in the record object itself. So changing it here will change it in both places. Please send any bug reports or features you add to: [louisaturk--eudoramail--com] 26-Jun-2001 G. Scott Jones, M.D. changed the following 1) Added check for existence of data file and check for empty data file. 2) Commented out hash until fully debugged 3) Changed name of update function for key data from change-data to update-key-data 4) Added default choice of 0 to avoid initial error 5) Added additional forever loop to allow editing of multiple fields in edit record section 6) Changed from if construct to switch inside edit record ? whether need to set choice to 0 anymore 7) Changed method for updating no-key fields 8) Added ability to edit key-field email from within edit record. ? whether need separate email update function. 9) Added checks for empty data on edit/update 10) Reset database to head after forskip (NB: forskip leaves the series pointer pointing at the tail) in print section 11) Changed csv import to leave data elements in same format as "native" data file format (namely, string). 12) Made a few miscellaneous formatting changes, including recommended REBOL indent 13) Other miscellaneous changes mostly commented in code. } ; End of Comments ] ;End of Rebol Script Header db-file: %data.r record: context [name: email: phone: web: none] ;Place the none value in all the varables. database: copy [] load-data: has [data] [ if exists? db-file [ data: load/all db-file clear database if data [ foreach item data [ item: make record item repend database [item/email item] ] ] ;database: make hash! database ] ] update-key-data: func [email-old email-new /local record] [ record: find database email-old if none? record [alert reform ["Missing record:" email-old] exit] insert clear first record email-new ; See note in feature #6 above. ] ; ? whether needed edit-data: func [field index /local record] [ record: find database field if none? record [alert reform ["Missing record:" field] exit] record/index: field ] save-data: has [data] [ data: copy [] foreach [key obj] database [ append/only data third obj ] save db-file data ] find-data: func [email] [select database email] remove-data: func [email] [remove/part find database email 2] insert-data: func [email' name' phone' web'] [ repend database [ email' make record [ email: email' name: name' phone: phone' web: web' ] ] ] {Holger and Jeff helped me with this function. I changed it some trying to learn how to use it.} kbhit: does [ con: open/direct/binary/no-wait console:// until [wait con] choice: to-char pick con 1 close con choice ] ;kbhit: does [ ; con: open/direct/binary/no-wait console:// ; until [wait con] ; first reduce [to-string copy con close con] ;] {Below is a simple character based user interface for REBOL/Core added by Louis A. Turk} load-data choice: 0 ; to avoid initial error forever [ cls: "^(1B)[J" ; Clear the Screen. print cls print "^/ REBOL RELATIONAL OBJECT-ORIENTED DBMS" ; ^/ is a line feed. print " =====================================^/" print " 1. Add Record." print " 2. Edit a Field In a Record." print " 3. Delete Record." print " 4. Change Email Address Only." print " 5. Print Reports." print " 6. Export Data To CSV File." print " 7. Import (APPEND) Data From CSV File." prin "^/ Enter the # of Choice (or ESC to Exit): " choice = kbhit ;may wish to change this to a switch construct in future if choice = #"1" [ forever [ print cls print " ADD A RECORD" print " ============^/" email: ask " Email Address: " if email = "" [break] ;gsj added to avoid empty error rec: find database email either rec = none [ name: ask " Full Name: " phone: ask " Area Code & Phone#: " web: ask " Website URL: " insert-data email name phone web save-data ][ ask "^/ Record is already in database. Continue? " ] ] ; End forever loop for choice 1 ] ; End if choice 1 if choice = #"2" [ forever [ print cls print " EDIT A FIELD IN A RECORD" print " ========================^/" email-old: ask " Email Address: " if email-old = "" [break] forever [ record: find database email-old if record = none [ print cls print "^/ Missing record: " email-old ask "^/ Hit Any Key To Continue." break ] record: find-data email-old print ["^/ 1. Email : " record/email] print [" 2. Name : " record/name] print [" 3. Phone : " record/phone] print [" 4. URL : " record/web] print [" 5. Return to Edit Menu" "^/"] prin [" Enter number of field to change: "] choice: kbhit ; I'm using this method of accessing fields since records in databases ; to be expanded from this one may have 10 to 30 fields with only ; one usually needing editing. switch/default choice [ #"1" [ print cls print " EDIT EMAIL ADDRESS" print " ==================^/" email-new: ask rejoin [" New Email Address to replace " email-old ": "] if email-new <> "" [ update-key-data email-old email-new save-data email-old: copy email-new ] choice: "0" ; Added this hack to solve a logic problem. ] #"2" [ print cls print " CHANGE NAME" print " ===========^/" new-name: ask rejoin ["Enter name to replace " record/name ": "] if new-name <> "" [record/name: copy new-name save-data] choice: "0" ] #"3" [ print cls print " CHANGE PHONE" print " ===========^/" new-phone: ask rejoin ["Enter phone to replace " record/phone ": "] if new-phone <> "" [record/phone: copy new-phone save-data] choice: "0" ] #"4" [ print cls print " CHANGE URL" print " ===========^/" new-url: ask rejoin ["Enter url to replace " record/web ": "] if new-url <> "" [record/web: copy new-url save-data] choice: "0" ] ][break] ;end of switch and switch/default ] ; end of forever for editing a record ] ; End forever loop ] ; End if choice 2 if choice = #"3" [ forever [ print cls print " DELETE A RECORD" print " ===============^/" email-old: ask " Email Address Of Record To Delete: " ;if email-old = "" [ ; break ;] ; End if. record: find database email-old if none? record [ print cls print " Record not found.^/" ask " Hit Any Key To Continue." break ] remove-data email-old save-data ] ; End forever loop for choice 3. ] ; End if choice 3 if choice = #"4" [ forever [ print cls print " CHANGE EMAIL ADDRESS ONLY" print " ==========================^/" email-old: ask " Email Address To Be Changed: " if email-old = "" [break] record: find database email-old if none? record [ print cls print "Missing record: " email-old ask "Hit Any Key To Continue." break ] email-new: ask rejoin [" New Email Address to replace " email-old ": "] if email-new <> "" [ update-key-data email-old email-new save-data ] ] ; End forever loop for choice 4 ] ; End if choice 4 {Scott Jones provided the core code for choices 4, 5, and 6 below.} if choice = #"5" [ print cls print " PRINT FORMATTED REPORTS" print " =======================^/" forskip database 2 [ print ["^/ Email: " database/2/email] print [" Name: " database/2/name] print [" Phone: " database/2/phone] print ["Web URL: " database/2/web] ] prin "^/Press any key to continue..." database: head database ;reset following forskip kbhit ] if choice = #"6" [ print cls print " EXPORT DATA TO CSV FILE" print " =======================^/" csv: ask "Name of CSV File to Write to: " either not csv = "" [ csv-file: to-file csv write csv-file "" ;to get fresh file emit: func [blk] [repend csv-line blk] forskip database 2 [ csv-line: make string! 1000 emit [{"} database/2/email {","} database/2/name {","} database/2/phone {","} database/2/web {"^/}] write/append csv-file csv-line ] database: head database ;reset following forskip prin "^/The file has been written. Continue? " kbhit ][prin "^/You forget to enter a file name. Continue? " kbhit] ] if choice = #"7" [ print cls csv: ask "Name of CSV File to Read From: " either not csv = "" [ csv-file: to-file csv data: read/lines csv-file foreach line data [ foreach [email name phone web] parse line none [ email: trim email name: trim name phone: trim phone web: trim web if not find-data email [insert-data email name phone web] save-data ] ] prin "^/The Data Has Been Appended to the Database. Continue? " kbhit ][prin "^/You forget to enter a file name. Continue? " kbhit] ] ] ; End forever loop for main program.