Re: display value of a key in dictionary to text box and edit value and save out to file - C# Discussion Boards

Re: How to Cache a DB2 Dynamic Query in ADO.net

kumarkoppireddy4-Oct-18 6:25

4-Oct-18 6:25

When you cache the data from a search query, then the database is updated with new data, how are you going to detect this and invalidate the cached copy of the data so a new search of the same query terms results in an updated dataset? God question this is not transactional data and we update data once in a day so i will just cache the query for the half day or 4 hours only.

Re: How to Cache a DB2 Dynamic Query in ADO.net

Dave Kreskowiak4-Oct-18 6:46

Dave Kreskowiak

4-Oct-18 6:46

Yeah, that's not going to work. Putting an arbitrary value on an items "time to live" will just result in search queries that could be out of date for a smaller period of time.

The code that updates the database has to be able to invalidate cached data. But you have a problem. How is your code going to know which cached queries are affected by a single update to the database?

Caching search queries is a bad idea.

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Dave Kreskowiak

Re: How to Cache a DB2 Dynamic Query in ADO.net

OriginalGriff4-Oct-18 6:32

OriginalGriff

4-Oct-18 6:32

Dave is absolutely right - by trying to cache data outside of the DB that you are sourcing from, you need to catch everything that happens to your DB and invalid specific portions of your cache if the change might have affected the results of a query. Otherwise, your cached data becomes increasingly out of date and useless.
For example, I issue a stock level request for Product A, and you return "2".
Next time I ask, it's in your cache, so you return "2" without going to the DB.
Then Joe over there sells one, and the DB gets updated to "1"
I ask again, it's in your cache, so you return "2" without going to the DB.
Joe sells anoth, and the DB gets updated to "0"
I ask again, it's in your cache, so you return "2" without going to the DB.
So the customer I'm talking to "knows" there are 2 in stock - and buys one. What happens now?

Unless you "stand in the middle" and pass each query through or serve them from your cache while intelligently invalidating the caches as appropriate, your data gets more and more irrelevant.
And that is going to slow down the whole process as well, because now you have effectively two sources of data processing every single command!

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Re: How to Cache a DB2 Dynamic Query in ADO.net

Mycroft Holmes4-Oct-18 12:48

Mycroft Holmes

4-Oct-18 12:48

I'm curious - your answer to 1 seems to imply that you and your users don't perceive a problem!

What is the latency on your results return, it seems to me that a query on a 900k should be trivial from a database POV. If it IS the database then look at indexing the user table, if the latency is the network then you have a different problem which should be resolved by your network people not by caching search results.

Never underestimate the power of human stupidity
RAH

display value of a key in dictionary to text box and edit value and save out to file

elfenliedtopfan53-Oct-18 14:02

elfenliedtopfan5

3-Oct-18 14:02

hello Code project i have created dictionary with key value pairs form a text file and i want to display the value of a key to a textbox

and edit the value in the textbox and on a button click save to the file this is the code i have so far just not sure how to add to textbox and save it out.

public class BO3_weapon_editor
{
    public static string outvalue { get; set; }

    public void processfile(string file)
    {
        Dictionary<string, string> dic = new Dictionary<string, string>();
         string data;
        {
                using (StreamReader reader = new StreamReader(file))
                {
                    string line;
                    while ((line = reader.ReadToEnd()) != null)
                    {
                    var patt = @"(?m)\s*""(.+?)""\s+""(.*?)""\s*";
                    foreach (Match m in Regex.Matches(line, patt))
                {
                     var k = m.Groups[1].Value;
                     var v = m.Groups[2].Value;
                     if (false == dic.ContainsKey(k)) dic[k] = v; else dic[k] += "," + v;
        }

                     outvalue = dic["adsUpAnim"];
                        }
                    }
                }



        }
    }

any help would be much appricated.

Re: display value of a key in dictionary to text box and edit value and save out to file

Maciej Los3-Oct-18 20:28

Maciej Los

3-Oct-18 20:28

It's pretty simple:

textbox1.Text = yourdictionary[key];
//then
yourdictionary[key] = textbox1.Text;

//save to text file here
string[] lines = yourdictionary
    .Select(kvp=> string.Concat(kvp.Key, "\t", kvp.Value))
    .ToArray();
File.WriteAllLines("fullfilename.txt", lines);

Note: i've used tab between key and value. You can replace this separator with another one.

modified 4-Oct-18 2:41am.

Re: display value of a key in dictionary to text box and edit value and save out to file

OriginalGriff3-Oct-18 20:35

OriginalGriff

3-Oct-18 20:35

You can read a value from a textBox very simply, by using it's Text property:

string myString = mMyTextBox.Text;

And you can use that anywhere you wanted - as the key value for a dictionary for example:

value = myDictionary[myTextBox.Text];

But ... the code you show creates the dictionary, but it then throws it away again, as it is only stored as a local variable in your processfile method. You need to decide what you want to do with your dictionary, and either return it from the method (if it's going to be relatively temporary), store it in a class level variable (if it's going to be needed for the whole life of the class instance), or in a static class level variable (if you need to share it between several instance of the class).

BTW: sort out your indentation! it's a mess, which means the code is probably a mess as well: Visual Studio helps you with the indentation as you go along, so bad indentation normally means your code doesn't compile because the system doesn't understand it!
And never do this:

if (false == dic.ContainsKey(k)) dic[k] = v; else dic[k] += "," + v;

There are two things wrong here:

if (false == x) ...

That's messy and hard to read. Us etehis instead:

if (!x) ...

The other is this:

if (x) y; else z;

Indent it, and (certainly while you are a beginner) always use brackets:

C++

if (x)
   {
   y;
   }
else
   {
   z;
   }

It doesn't matter what bracketing style you use, as long as you are consistent:

C++

if (x)
{
   y;
}
else
{
   z;
}

Works as well.
So your code ends up as:

if (!dic.ContainsKey(k))
   {
   dic[k] = v; 
   }
else 
   {
   dic[k] += "," + v;
   }

But for advanced users, we'd go with:

dic[k] = dic.ContainsKey(k)) ? dic[k] + "," + v : v;

Sent from my Amstrad PC 1640
Never throw anything away, Griff
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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Re: display value of a key in dictionary to text box and edit value and save out to file

dan!sh 3-Oct-18 20:36

dan!sh

3-Oct-18 20:36

You probably need to make use of another control than TextBox since there will be more than one pair in the Dictionary. Perhaps take a look at ListBox or DataGridView.

You can loop through the Dictionary like this:

foreach (string s in dic.Keys)
{
// Add values to control here. s will be the key and dic[s] will be the value
}

Once user edits are done, on the button click you can again get all the values and write then to a file. You can opt to use StreamWriter for it.

using (StreamWriter writer = new StreamWriter("file path here"))
{
        // Loop through controls (this will depend on the control you opt for)
    writer.WriteLine("line to write here");
}

"It is easy to decipher extraterrestrial signals after deciphering Javascript and VB6 themselves.", ISanti[^]

Re: display value of a key in dictionary to text box and edit value and save out to file

BillWoodruff14-Oct-18 15:21

BillWoodruff

14-Oct-18 15:21

You may wish to consider another data structure if you have the possibility of duplicate keys.

«Where is the Life we have lost in living? Where is the wisdom we have lost in knowledge? Where is the knowledge we have lost in information?» T. S. Elliot

OPC client server

Roberto64_Ge3-Oct-18 2:28

Roberto64_Ge

3-Oct-18 2:28

Hi
I'm trying to implement an OPC client to connect to the FactoryTalk Gateway opc server from Rockwell.
I get an example and I am trying to use it but with some problems.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace RsLinx_OPC_Client
{
    public partial class Form1 : Form
    {
        #region Variables for OPC client

        private Opc.URL url;
        private Opc.Da.Server server;
        private OpcCom.Factory fact = new OpcCom.Factory();
        private Opc.Da.Subscription groupRead;
        private Opc.Da.Subscription groupWrite;
        private Opc.Da.SubscriptionState groupState;
        private Opc.Da.SubscriptionState groupStateWrite;
        private Opc.Da.Item[] items = new Opc.Da.Item[3];
        
        #endregion

        //initialization of the sample object that contains opc values
        MyOPCObject myOpcObject = new MyOPCObject();

        public Form1()
        {
            InitializeComponent();
        }

        private void btnConnect_Click(object sender, EventArgs e)
        {
            //string nomenodo;
            //Opc.ConnectData myopc_connectdata = new Opc.ConnectData(new System.Net.NetworkCredential());
            // 1st: Create a server object and connect to the RSLinx OPC Server
            // url = new Opc.URL("opcda://localhost/RSLinx OPC Server");
            // url = new Opc.URL("FactoryTalk Gateway");
            url = new Opc.URL("opcda://localhost/FactoryTalk Gateway");
            //nomenodo = "PCA079";
            // url = new Opc.URL("opc.tcp://PCA079:4990/FactoryTalkLinxGateway_RS");
            // url = new Opc.URL("RSLinx OPC Server");
            server = new Opc.Da.Server(fact, null);

            //2nd: Connect to the created server
            server.Connect(url, new Opc.ConnectData(new System.Net.NetworkCredential()));
            //try
            //{
            //    server.Connect(url, myopc_connectdata);
            //}
            //catch (Exception exy)
            //{
            //    MessageBox.Show(exy.Message);

            //}
            //3rd Create a group if items            
            groupState = new Opc.Da.SubscriptionState();
            groupState.Name = "Group";
            groupState.UpdateRate = 1000;// this isthe time between every reads from OPC server
            groupState.Active = true;//this must be true if you the group has to read value
            groupRead = (Opc.Da.Subscription)server.CreateSubscription(groupState);
            groupRead.DataChanged += new Opc.Da.DataChangedEventHandler(group_DataChanged);//callback when the data are readed
            
            // add items to the group    (in Rockwell names are identified like [Name of PLC in the server]Block of word:number of word,number of consecutive readed words)        
            items[0] = new Opc.Da.Item();
            items[0].ItemName = "[UNTITLED_1]N7:0,L2";//this reads 2 word (short - 16 bit)
            items[1] = new Opc.Da.Item();
            items[1].ItemName = "[UNTITLED_1]N11:0,L10";//this reads an array of 10 words (short[])
            items[2] = new Opc.Da.Item();
            items[2].ItemName = "[UNTITLED_1]B3:0,L2";//this read a 2 word array (but in the plc the are used as bits so you have to mask them)    
            items = groupRead.AddItems(items);

            // Create a write group            
            groupStateWrite = new Opc.Da.SubscriptionState();
            groupStateWrite.Name = "Group Write";
            groupStateWrite.Active = false;//not needed to read if you want to write only
            groupWrite = (Opc.Da.Subscription)server.CreateSubscription(groupStateWrite);
        }

EXception is thrown in the

server.Connect(url, new Opc.ConnectData(new System.Net.NetworkCredential()));

The exception in italian tells that

Quote:
Eccezione non gestita di tipo 'System.IO.FileNotFoundException' in OpcNetApi.dll

Ulteriori informazioni: Impossibile caricare il file o l'assembly 'OpcRcw.Dx, Version=1.0.1.21, Culture=neutral, PublicKeyToken=9a40e993cbface53' o una delle relative dipendenze. Impossibile trovare il file specificato.

Which means that it is impossible to load file or assembly 'OpcRcw.Dx, Version=1.0.1.21, Culture=neutral, PublicKeyToken=9a40e993cbface53' or relevant dependecies

Can somebody help?
Regards