docs.intersystems.com
Home  /  Application Development: Core Topics  /  ObjectScript Tutorial  /  Exercise 7: Third Lookup Class


ObjectScript Tutorial
Exercise 7: Third Lookup Class
[Back]
InterSystems: The power behind what matters   
Search:  


Click here to return to the exercise description in the main part of the tutorial.
  1. Start by editing the Store() method of ObjectScript.DataEntry4. Add a TStart just before storing the user's answers in the ^PersonD global.
        // change all globals inside a transaction
        tstart
        set ^PersonD(id) = answers  // store the answers
    
    Add a TCommit just after updating the indices in the ^PersonI global.
        set $bit(^PersonI("Bitmap-ID", chunk), position) = 1
        tcommit
        write "...stored"    
    
    Normally, only statements that set or kill globals should be between TStart and TCommit, but you'll leave Store() otherwise unchanged.
  2. Click the Save and Compile buttons.
  3. Change the top line of ObjectScript.Lookup2 to ObjectScript.Lookup3, and save it as ObjectScript.Lookup3.
  4. Add this code to TakeAction() to give the user the option of deleting the record.
        // ask if user wants to delete
        read !, "Delete? (y/n): ", yn
        if ((yn = "y") || (yn = "Y")) {
            do ..Delete(id, record)
            quit
        }
    
  5. Write the new Delete() method.
    Class ObjectScript.Lookup3
    {
    
    /// delete chosen record (lock, start a txn, kill global nodes, commit txn, unlock)
    ClassMethod Delete(id as %Integer, record as %String)
    {
        // try to lock the record for 5 seconds
        lock +^PersonD(id):5
        if '$test {
            write "...someone else is editing this person. Try again later."
            quit
        }
        // retrieve data
        set $listbuild(name, phone, intdob) = record
        set last = $piece(name, ",", 1), first = $piece(name, ",", 2)
        set chunk = (id\64000) + 1, position = (id#64000) + 1
        
        // change all globals inside a transaction
        tstart
        kill ^PersonD(id)
        kill ^PersonI("Name", last, first, id)
        kill ^PersonI("Phone", phone)
        kill ^PersonI("DOB", intdob, id)
        set $bit(^PersonI("Bitmap-ID", chunk), position) = 0
        tcommit
        write "...deleted"
        lock -^PersonD(id)
    }
    }
  6. Click the Save and Compile buttons.
  7. Start Terminal, and run your method to test the new deletion option, by typing do ##class(ObjectScript.Lookup3).Main().
  8. Add this code to TakeAction() to give the user the option of editing the record.
        // ask if user wants to edit
        read !, "Edit? (y/n): ", yn
        if ((yn = "y") || (yn = "Y")) {
            do ..Edit(id, record)
            quit
        }
    
  9. Write the new Edit() method.
    Class ObjectScript.Lookup3
    {
    
    /// edit chosen record (lock, reprompt, compare, update globals, unlock)
    ClassMethod Edit(id as %Integer, record as %String)
    {
        // try to lock the record for 5 seconds
        lock +^PersonD(id):5
        if '$test {
            write "...someone else is editing this person. Try again later."
            quit
        }
        // show current data and prompt for updates
        do ..Reprompt(record, .newanswers)
        // if changes were made, update the record
        if '$listsame(record, newanswers) {do ..Update(id, record, newanswers)}
        lock -^PersonD(id)
    }
    }
  10. Write the new Reprompt() method.
    Class ObjectScript.Lookup3
    {
    
    /// prompt for updates - similar to ##class(ObjectScript.DataEntry4).Prompt()
    ClassMethod Reprompt(currentdata as %String, ByRef newanswers as %String)
    {   
        // get current name, phone, intdob so that they can be displayed within prompts
        set $listbuild(currentname, currentphone, currentintdob) = currentdata
        do {
            write !, "Name: ", currentname, " => "
            read newname
            // enter nothing to keep current value
            if (newname = "") {
                set newname = currentname
                quit
            }
         }
        while '##class(ObjectScript.DataEntry4).ValidName(newname)
        
        do {
            write !, "Phone: ", currentphone, " => "
            read "(617): ", newphone
            // enter nothing to keep current value
            if (newphone = "") {
                set newphone = currentphone
                quit
            }
        }
        while '##class(ObjectScript.DataEntry4).ValidPhone(.newphone)
    
        do {
            write !, "DOB: ", $zdate(currentintdob, 2), "=> "
            read newdob
            // enter nothing to keep current value
            if (newdob = "") {
                set newintdob = currentintdob
                quit
            }
        }
        while '##class(ObjectScript.DataEntry4).ValidDOB(newdob, .newintdob)
    
        set newanswers = $listbuild(newname, newphone, newintdob)
    }
    }
  11. Write the new Update() method.
    Class ObjectScript.Lookup3
    {
    
    /// save the updated record (start a txn, updating data and index globals using set and kill, commit txn)
    ClassMethod Update(id as %Integer, currentdata as %String, ByRef newanswers as %String)
    {
        read !, "Store updates? (y/n): ", yn  // ask if user wants to store
        // only go on if user says yes
        if ((yn '= "y") && (yn '= "Y")) {
            write "...not stored."
            quit
        }
        
        // get current and new data for comparisons
        set $listbuild(currentname, currentphone, currentintdob) = currentdata
        set currentlast = $piece(currentname, ",", 1), currentfirst = $piece(currentname, ",", 2)
        set $listbuild(newname, newphone, newintdob) = newanswers
        set newlast = $piece(newname, ",", 1), newfirst = $piece(newname, ",", 2)    
    
        // update all globals inside a transaction
        // only update indices if the data was changed    
        tstart
        set ^PersonD(id) = newanswers
        if (newname '= currentname) {
            // kill old name and add new name to index
            kill ^PersonI("Name", currentlast, currentfirst, id)
            set ^PersonI("Name", newlast, newfirst, id) = ""
        }
        if (newphone '= currentphone) {
            // kill old phone and add new phone to index
            kill ^PersonI("Phone", currentphone)
            set ^PersonI("Phone", newphone) = id
        }
        if (newintdob '= currentintdob) {
            // kill old dob and add new dob to index
            kill ^PersonI("DOB", currentintdob, id)
            set ^PersonI("DOB", newintdob, id) = ""
        }
        tcommit  // commit the transaction
        write "...updated."    
    }
    }
  12. Click the Save and Compile buttons.
  13. Start Terminal, and run your method to test the new editing option, by typing do ##class(ObjectScript.Lookup3).Main().