Merge pull request #123 from Herder-IT-Solutions/database

#116 Which DateTime is nil?

lazarus/DBConnection.pas

@@ -6,7 +6,7 @@ interface
 
 uses
   Classes, SysUtils, sqlite3conn, sqldb, DB, FileUtil, Forms, Controls,
-  Graphics, Dialogs, DBGrids, book, booktype, rental, student;
+  Graphics, Dialogs, DBGrids, book, booktype, rental, student, DBConstants;
 
 type
   ArrayOfStudents = array of TStudent;
@@ -195,7 +195,10 @@ procedure TDBConnection.setStudentFields(var resultVar: ArrayOfStudents;
           FieldByName('first_name').AsString);
         resultVar[length(resultVar) - 1].setClassName(
           FieldByName('class_name').AsString);
-        resultVar[length(resultVar) - 1].setBirth(FieldByName('birth').AsDateTime);
+
+        if not (FieldByName('birth').IsNull) then
+          resultVar[length(resultVar) - 1].setBirth(FieldByName('birth').AsDateTime);
+
         resultVar[length(resultVar) - 1].setLDAPUser(FieldByName('ldap_user').AsString);
         if returnOne then
           exit;
@@ -419,7 +422,12 @@ function TDBConnection.updateInsertStudent(student: TStudent): boolean;
       FieldByName('last_name').AsString := student.getLastName;
       FieldByName('first_name').AsString := student.getFirstName;
       FieldByName('class_name').AsString := student.getClassName;
-      FieldByName('birth').AsDateTime := student.getBirth;
+
+      if student.getBirth = SQLNull then //if set to null
+        FieldByName('birth').Clear
+      else
+        FieldByName('birth').AsDateTime := student.getBirth;
+
       FieldByName('ldap_user').AsString := student.getLDAPUser;
       Post; //add to change buffer
       ApplyUpdates; //commit change buffer to db
@@ -481,8 +489,11 @@ procedure TDBConnection.setRentalFields(var resultVar: ArrayOfRentals;
         resultVar[length(resultVar) - 1].setBookId(FieldByName('book_id').AsLargeInt);
         resultVar[length(resultVar) - 1].setStudentId(
           FieldByName('student_id').AsLargeInt);
-        resultVar[length(resultVar) - 1].setReturnDate(
-          FieldByName('return_date').AsDateTime);
+
+        if not (FieldByName('return_date').IsNull) then
+          resultVar[length(resultVar) - 1].setReturnDate(
+            FieldByName('return_date').AsDateTime);
+
         resultVar[length(resultVar) - 1].setRentalDate(
           FieldByName('rental_date').AsDateTime);
         if returnOne then
@@ -578,7 +589,12 @@ function TDBConnection.updateInsertRental(rental: TRental): boolean;
       FieldByName('student_id').AsLargeInt := rental.getStudentId;
       FieldByName('book_id').AsLargeInt := rental.getBookId;
       FieldByName('rental_date').AsDateTime := rental.getRentalDate;
-      FieldByName('return_date').AsDateTime := rental.getReturnDate;
+
+      if rental.getReturnDate = SQLNull then //if set to null
+        FieldByName('return_date').Clear
+      else
+        FieldByName('return_date').AsDateTime := rental.getReturnDate;
+
       Post; //add to change buffer
       ApplyUpdates; //commit change buffer to db
       SQLTransaction.commit;
@@ -669,8 +685,11 @@ procedure TDBConnection.setBookFields(var resultVar: ArrayOfBooks; returnOne: bo
         resultVar[length(resultVar) - 1] := TBook.Create; //create new book object
         resultVar[length(resultVar) - 1].setId(FieldByName('id').AsLargeInt);
         resultVar[length(resultVar) - 1].setIsbn(FieldByName('isbn').AsString);
-        resultVar[length(resultVar) - 1].setCondition(
-          FieldByName('condition').AsInteger);
+
+        if not (FieldByName('condition').IsNull) then
+          resultVar[length(resultVar) - 1].setCondition(
+            FieldByName('condition').AsInteger);
+
         if returnOne then
           exit;
         Next;
@@ -824,7 +843,10 @@ procedure TDBConnection.setBooktypeFields(var resultVar: ArrayOfBookTypes;
         resultVar[length(resultVar) - 1].setIsbn(FieldByName('isbn').AsString);
         resultVar[length(resultVar) - 1].setTitle(FieldByName('title').AsString);
         resultVar[length(resultVar) - 1].setSubject(FieldByName('subject').AsString);
-        resultVar[length(resultVar) - 1].setStorage(FieldByName('storage').AsInteger);
+
+        if not (FieldByName('storage').IsNull) then
+          resultVar[length(resultVar) - 1].setStorage(FieldByName('storage').AsInteger);
+
         if returnOne then
           exit;
         Next;

lazarus/book.pas

@@ -5,7 +5,7 @@
 interface
 
 uses
-  Classes, SysUtils;
+  Classes, SysUtils, DBConstants;
 
 type
   TBook = class
@@ -38,7 +38,7 @@   TBook = class
 
     // Sets a new book condition
     // parameter: newCondition
-    // result: TRUE on success, so if newIsbn has 1 character, is <=5 and not NULL
+    // result: TRUE on success, so if newIsbn has 1 character, is <=5 or is =SQLNull
     function setCondition(newCondition: cardinal): boolean;
 
     constructor Create;
@@ -97,7 +97,7 @@ function TBook.getCondition(): cardinal;
 function TBook.setCondition(newCondition: cardinal): boolean;
 begin
   Result := False;
-  if (newCondition <= 6) then
+  if (newCondition = SQLNull ) or (newCondition <= 6) then
   begin
     self.condition := newCondition;
     Result := True;
@@ -106,9 +106,9 @@ function TBook.setCondition(newCondition: cardinal): boolean;
 
 constructor TBook.Create;
 begin
-  self.id := -1;
+  self.id := SQLNull;
   self.isbn := '';
-  self.condition := 0;
+  self.condition := SQLNull;
 end;
 
 end.

lazarus/booktype.pas

@@ -5,7 +5,7 @@
 interface
 
 uses
-  Classes, SysUtils;
+  Classes, SysUtils, DBConstants;
 
 type
   TBooktype = class
@@ -48,7 +48,7 @@   TBooktype = class
 
     // Sets a new book storage
     // parameter: newStorage
-    // result: TRUE on success, so if newStorage <= (2^63)-1)
+    // result: TRUE on success, so if newStorage <= (2^63)-1) or =SQLNull
     function setStorage(newStorage: integer): boolean;
 
     constructor Create;
@@ -119,7 +119,7 @@ function TBooktype.getStorage(): integer;
 function TBooktype.setStorage(newStorage: integer): boolean;
 begin
   Result := False;
-  if (newStorage <> NULL) then
+  if (newStorage = SQLNull) or (newStorage <> NULL) then
   begin
     self.storage := newStorage;
     Result := True;
@@ -131,7 +131,7 @@ constructor TBooktype.Create;
   self.isbn := '';
   self.title := '';
   self.subject := '';
-  self.storage := 0;
+  self.storage := SQLNull;
 end;
 
 end.

lazarus/dbconstants.pas

@@ -0,0 +1,12 @@
+unit DBConstants;
+
+{$mode objfpc}{$H+}
+
+interface
+
+const
+  SQLNull = -1;
+
+implementation
+
+end.

lazarus/rental.pas

@@ -5,51 +5,51 @@
 interface
 
 uses
-  Classes, SysUtils;
+  Classes, SysUtils, DBConstants;
 
 type
   TRental = class
   private
-    id: LongInt;
-    book_id: LongInt;
-    student_id: LongInt;
+    id: longint;
+    book_id: longint;
+    student_id: longint;
     return_date: TDate;
     rental_date: TDate;
   public
     // Returns the id
     // result: id
-    function getId(): LongInt;
+    function getId(): longint;
 
     // Sets a new id
     // parameter: newId
     // result: TRUE on success, so if newID is not NULL
-    function setId(newId: LongInt): boolean;
+    function setId(newId: longint): boolean;
 
     // Returns the book id
     // result: book_id
-    function getBookId(): LongInt;
+    function getBookId(): longint;
 
     // Sets a new book id
     // parameter: newBookId
     // result: TRUE on success, so if newBookID is not NULL
-    function setBookId(newBookId: LongInt): boolean;
+    function setBookId(newBookId: longint): boolean;
 
     // Returns the student id
     // result: student_id
-    function getStudentId(): LongInt;
+    function getStudentId(): longint;
 
     // Sets a new sudent id
     // parameter: newStudentId
     // result: TRUE on success, so if new StudentId is not NULL
-    function setStudentId(newStudentId: LongInt): boolean;
+    function setStudentId(newStudentId: longint): boolean;
 
     // Returns the book return date
     // result: return_date
     function getReturnDate(): TDate;
 
     // Sets a new book return datetime in seconds
     // parameter: newReturnDate
-    // result: TRUE on success, so if newReturnDate >= 0 and not NULL
+    // result: TRUE on success, so if newReturnDate >= 0 or =SQLNull
     function setReturnDate(newReturnDate: TDate): boolean;
 
     // Returns the book rental datetime in seconds
@@ -66,12 +66,12 @@   TRental = class
 
 implementation
 
-function TRental.getId(): LongInt;
+function TRental.getId(): longint;
 begin
   Result := self.id;
 end;
 
-function TRental.setId(newId: LongInt): boolean;
+function TRental.setId(newId: longint): boolean;
 begin
   Result := False;
   if (newId <> NULL) then
@@ -81,12 +81,12 @@ function TRental.setId(newId: LongInt): boolean;
   end;
 end;
 
-function TRental.getBookId(): LongInt;
+function TRental.getBookId(): longint;
 begin
   Result := self.book_id;
 end;
 
-function TRental.setBookId(newBookId: LongInt): boolean;
+function TRental.setBookId(newBookId: longint): boolean;
 begin
   Result := False;
   if (newBookId <> NULL) then
@@ -96,12 +96,12 @@ function TRental.setBookId(newBookId: LongInt): boolean;
   end;
 end;
 
-function TRental.getStudentId(): LongInt;
+function TRental.getStudentId(): longint;
 begin
   Result := self.student_id;
 end;
 
-function TRental.setStudentId(newStudentId: LongInt): boolean;
+function TRental.setStudentId(newStudentId: longint): boolean;
 begin
   Result := False;
   if (newStudentId <> NULL) then
@@ -119,7 +119,7 @@ function TRental.getReturnDate(): TDate;
 function TRental.setReturnDate(newReturnDate: TDate): boolean;
 begin
   Result := False;
-  if (newReturnDate <> NuLL) and (newReturnDate >= 0) then
+  if (newReturnDate = SQLNull) or (newReturnDate <> NuLL) and (newReturnDate >= 0) then
   begin
     self.return_date := newReturnDate;
     Result := True;
@@ -143,11 +143,11 @@ function TRental.setRentalDate(newRentalDate: TDate): boolean;
 
 constructor TRental.Create;
 begin
-  self.id := -1;
-  self.book_id := -1;
-  self.student_id := -1;
-  self.return_date := -1;
-  self.rental_date := -1;
+  self.id := SQLNull;
+  self.book_id := SQLNull;
+  self.student_id := SQLNull;
+  self.return_date := SQLNull;
+  self.rental_date := SQLNull;
 end;
 
 end.

lazarus/student.pas

@@ -5,7 +5,7 @@
 interface
 
 uses
-  Classes, SysUtils;
+  Classes, SysUtils, DBConstants;
 
 type
   TStudent = class
@@ -168,11 +168,11 @@ function TStudent.setLDAPUser(newLDAPUser: string): boolean;
 
 constructor TStudent.Create;
 begin
-  self.id := -1;
+  self.id := SQLNull;
   self.last_name := '';
   self.first_name := '';
   self.class_name := '';
-  self.birth := -1;
+  self.birth := SQLNull;
   self.ldap_user := '';
 end;