C# :: Cyclic References In A Database Access Layer
Jan 21, 2015
I'm looking to implement a Database Access Layer for the project I'm working on, it's a mature project and I'm trying to simplify the database access and as far as possible and remove the Database logic from the Business logic.
Bringing in an ORM solution isn't an option at the moment so I'm looking at bringing in DAO objects to break the coupling. The problem I can't get around in my head is how to avoid Cyclic references
We currently have 2 projects
BL contains types such as Customer, Component and Product which need saving to the Database, the Database project can't know about these items or it would create the cyclic dependency.
I tried adding Dao items to the DB project to mirror these items and to also mirror the DB structure but that requires that the BL project knows how to convert between it's own types and the DAO types which is something I'd like to avoid.
I also tried inserting a third intermediate project that would control the conversion and saving, I called it my DAL project and tried adding functions that would take the BL item and perform CRUD operations but again I ran into the cyclic dependency issue.
My ideal solution would be that the BL project would just have to call a function along the lines of "SaveCustomer(Customer inCustomer)" and not have to worry about doing any conversion.
Is there a project structure that would allow for this?
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Jul 25, 2014
I read online about Cyclic Redundancy Check and how it works.
ThisStack Overflow response explains it so well on a layman level.
I found some code online on how to implement it and what library to include in C#. I've looked at it and I can grasp how the algorithm works with the remainders.
What I don't understand is how can I integrate my database, which is a sql server localdb file into the CRC32 check, so that I can test for the database integrity. I'm not sure how to proceed.
Do I test each table individually and send the size of the table(in bytes) and compare it to the value it's supposed to be?
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Dec 12, 2014
I have:
An Access database in which the picture right now is saved by its directory, together with other field like title, publisher, developer,..
Visual Studio form in which a load button gets that directory as text
Details button that reads the ID of a selected item (I have a list of games) and displays the corresponding picture by reading the directory
The problem right now is that once someone else opens the program on his/her computer, the directory changes, making the whole thing useless.
Is there a way to get around this problem? The books I've been reading don't really adress this.
Directory is a string in class 'Game'; it's short text in the database
private void buttonFoto_Click(object sender, EventArgs e) {
LoadNewFile();
}
private void LoadNewFile() {
OpenFileDialog ofd = new OpenFileDialog();
[code].....
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Mar 17, 2014
I want to connect an access database (.mdb) to my Windows Forms application - this I can do and I have no problems viewing my table in server explorer.
Some code example or template that I can use as a base to learn from - I have literally trawled Google and Youtube and cannot find what I am after.
What I want to do is have a basic form, 2 text boxes and a button to save the data to my database.
FirstName and LastName are the 2 boxes.
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Jan 21, 2014
I have application that codes and binds an access database to a windows form application. Everything seems to work however, nothing is actually saved in the database. Updates and deletes are coded and debugging steps through, but checking the db, the data is the same.
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Jan 31, 2013
I have an application which inserts large amount of data in Access database. So to speed up the things i have set Indexed property to No.
So at the end of insertion i need to set the index to the column of the one of the table to Indexed (Duplicates OK) through C#.
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Oct 4, 2014
I have an extremely annoying problem, I am inserting data into an access database and now i have noticed that it is copying itself to the bin/debug folder on ts own and yet i have set "Copy to Output Directory" property to "Copy never"
But without fail, it is copied! It is making any attempted updates to the database's information invalid since its not updating at all.
This all started when i installed crystal reports and it asked me to make a duplicate of the database in order to utilize data-sets that were created for certain reports.
Why this is happening? I cannot test my application properly at all.
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Sep 29, 2012
i have to upload a ms access database file to the server from my client program. The server program should connect to this database and read the data. What's the easiest way to upload the file? Is it FTP? i tried sockets, but it only allows like 9kb of data transfer capacity.
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Feb 21, 2014
private void update_Click(object sender, EventArgs e) {
OleDbConnection conn = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;
Data Source=C:UsersshobhitDocumentsEnvironment_Monitoring.accdb;
Jet OLEDB:Database Password=divya6");
String sdat = dateTimePicker1.Value.ToShortDateString();
String la = labs.SelectedItem.ToString();
[Code] ....
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Mar 14, 2015
I've been trying to make a program to return node values for the shortest path from one node to another. I've searched up several algorithms like the Bellman Ford, A*, or Dijkstra and tried to think of ways to implement them if I store my map as a matrix. I've considered using a hash table, but since I am only a beginner, I am having trouble trying to understand how the concepts would translate into C.
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Sep 9, 2013
if we don't provide the acces modifiers for base class and we need to manipulate the private data of base class in derived class. Is there anyway to acces the private data members? Here's a coding example
class A {
private :
int a;
};
class B : public class A {
public :
void displayA() { cout<<a<<endl; }
};
how i can acces the a of base class A in derived class B without acces modifiers.
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Apr 22, 2013
Did a little Googling on this but couldn't find anything definitive. Is it safe to do something like
Code:
void MyClass::myFunc(){
my_type_t &foo = some_obj->get_member_reference();
store_for_later(&foo);
}
Then at some pointer later in execution, another function uses the pointer passed to store_for_later.
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May 28, 2013
I have the following code segment:
Code:
void Swap(Number& num1, Number& num2)
{
cout<<"Before swap:"<<num1<<" "<<num2<<endl;
Number& temp=num1;
num1=num2;
num2=temp;
cout<<"After swap:"<<num1<<" "<<num2<<endl;
}
[code]...
to which the output is:
Code:
Before swap:13 11
After swap:13 11
13 11 that seems confusing.
why doesn't Swap() swap the two Numbers?
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Jan 11, 2014
I am trying to make a utility program for work that will update multiple projects with local dll references. Basically I work with two solutions (for talk sake solutIon1 and solutIon2). Generally solutIon1 will reference the dll's built In solutIon2 which reside on a server. However for debugging proposes I sometimes need to D/L the solutIon2 projects and build them local-ally, so that I can reference the solutIon2 dll's local-ally (this Is so that I can easily attach the dll and step Into the code). However this require changing the reference paths, so that I am pointing to the local-ally built dll's, which Is quite a laborious task.
So the question is how would I update references in solution1 from the program that I am making. I don't really know what to start reading about as I have never done anything like this before.
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Jun 19, 2014
I am attempting to combine two vectors into a vector of pairs. I want to be able to alter the first and second of each pair and have those alterations reflected in the original vectors. I thought the following code might work but get compilation errors about a lack of viable overload for "=" for the line with the call to std::transform:
void f()
{
std::vector<int> a = {1,2,3,4,5};
std::vector<int> b = {6,7,8,9,0};
[Code].....
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Sep 26, 2014
Is it permissible to declare, for example, `std::valarray<int&>`? If so, how do I initialize such if the `valarray` is a class member?
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Dec 30, 2014
What rvalue references are? How are they useful? What are temporary objects?
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Jun 18, 2014
I am checking to see if two references are bound to the same object. My instincts tell Me, "Check their addresses. If they match, they are bound to the same." At the same time, I have not found anything in the C++ standard which would support this approach. Am I missing something? Is there wording which backs up My instincts? Is there a standard function to do this?
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Aug 20, 2013
I have this basic prototype:
struct int_wrapper{int i;};
template <const int_wrapper&... IPack>
void display_all(const int_wrapper&, IPack...);
But when I try to compile it, the compiler says IPack is not a type on the last line. Are packs of references not allowed?
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Apr 3, 2014
I was wondering if there is way to convert a C# class to its own project and it automatically keeps its references.
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Mar 6, 2015
Is it possible to create a class that stores (non-const) references to some objects and enables users direct access by using range-based for loops on them?
Code: class container {
public:
void add(int& value);
void remove(int& value);
...
};
int main()
{
container c;
for (auto& value:c) {
// `value' should be accessible as type `int&' instead of being a pointer, `std::reference_wrapper<int>' or something like that
}
}
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Dec 14, 2014
I'm having some problems in understanding how the code below works and why it produces the output it produces.. What I'd expect is that both functions, namely `add_1' and `add_2', would print the same output; but I've been proven wrong :/ So why does the second one get different memory addresses for the same variable?
Code should be self-explaining:
Code: template<typename... Types>
void add_1(Types&&... values)
{
// by the way: why do i have to use `const int' instead of `int'?
std::vector<std::reference_wrapper<const int>> vector{
std::forward<Types>(values)...};
std::cout << "add_1:" << std::endl;
for (const auto& value:vector) {
std::cout << &value.get() << std::endl;
[code].....
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Nov 15, 2014
I have an abstract class named Terrain, and a class named RoadMap, which supposed to hold an N*N array of Terrains. But I'm not sure what type should the RoadMap class hold:
Code:
#ifndef TERRAIN_H
#define TERRAIN_H
class Terrain {
[Code] ....
I can't use an array of refernces here, so I tried this:
Code: Terrain** terrain; and then I thought this was the way to go:
Code: Terrain (*terrain)[]; But now I'm not sure.
The N*N matrix size supposed to be determined according to a given input... What type should I use there?
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Jan 28, 2014
#include "stdafx.h"
#include <iostream>
#include <math.h>
#include <time.h>
#include<iomanip>
#include<array>
#include <algorithm>
using namespace std;
const int AS = 6;
void FillingRandomly(int (*)[AS]);
void printing(int (*)[AS]);
[Code] ....
Basically I have to create an array, fill it, and then print it on screen. The tricky thing is that need to use pointers to fill it and print and later on sort it. My problem is that with this code is that i get
Error2error C2109: subscript requires array or pointer typec:userspcdesktopusbanthonydocumentsvisual studio 2012projectsessaieessaieessaie.cpp55
and
5IntelliSense: expression must have pointer-to-object typec:UserspcDesktopUSBAnthonyDocumentsVisual Studio 2012ProjectsEssaieEssaieEssaie.cpp55
Whenever I try to run it.
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Aug 13, 2014
I am trying to understand RValue-references as return values of functions. First let's consider a simple function, that transforms a string into upper case letters.
const std::string
toUpper(std::string orig) {
std::transform(orig.begin(), orig.end(), orig.begin(), ::toupper);
return orig;
[Code] .....
It compiles, but I get the output 0 . Here I am wondering why the code above does not move the substr correctly while the code below does (prints out 1):
const std::string&&
no_sense(std::string abc) {
abc = abc.substr(1, 1);
return std::move(abc);
[Code] .....
In both cases abc is a temporary object inside of the function and gets deleted after the function is left. But why does the second version work and the first one does not?
cat.substr(1, 1)
And as my last question. Why doesn't
return std::move(abc.substr(1, 1));
work?
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May 5, 2013
Why cant a dynamic memory allocation work with references? I was told that references work with const pointers deep down so shouldn't this be legal code?
int &&a=new int;
My compiler says that a entity of int* cannot be used to initialize a entity of int&&?
Does that mean that the compiler thinks of them as different types except deep down a reference is implemented with a pointer? Is this right?
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