Static Cache Problem

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Hi,

I am caching my xml data into a data set as given below:

C#

public static void LoadCache()
{
    static DataSet ds = new DataSet();
    ds.ReadXml(HttpContext.Current.Server.MapPath("myXML.xml"));
    HttpRuntime.Cache.Insert("myCache", ds,null, Cache.NoAbsoluteExpiration,
                             Cache.NoSlidingExpiration, CacheItemPriority.High, null);
}

//Method to Call Cache
public DataSet GetXMLData()
{
    if (HttpRuntime.Cache["myCache"] == null)
    {
        LoadCache();
    }
    return (DataSet)HttpRuntime.Cache["myCache"];
}

Now I have a dataset dsData In my page load that is filled from this cache and I do the following:

C#

DataView dv = dsData.Tables[0].DefaultView;
dv.RowFilter = "key=0";
DataTable dtTemp = dv.ToTable();
dtTemp.Columns.Add("sort"); //Works fine only once

The above chunk works only for once, when I refresh my page it shows Column with same name already exist in dtTemp.

Also when I tried Debugging I found Out that The Cache Dataset ds also contains same column.
I am unable to figure out why this happens.

Posted 1-Sep-14 19:47pm

ChintanShukla

Updated 1-Sep-14 22:37pm

George Jonsson

v3

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George Jonsson · Answer 1 · 2014-09-01T20:02:00

I revised my first answer as it did not answer the question.
I still don't have an answer, after trying the code below.
It works fine as far as I can see.

C#

static DataSet ds = new DataSet();
public static void LoadCache()
{

    DataTable dt = ds.Tables.Add();
    dt.Columns.Add("key", typeof(int));
    dt.Columns.Add("name", typeof(string));

    dt.Rows.Add(0, "Donald");
    dt.Rows.Add(0, "Duck");
    dt.Rows.Add(1, "Mickey");
    dt.Rows.Add(1, "Mouse");

    HttpRuntime.Cache.Insert("myCache", ds, null, Cache.NoAbsoluteExpiration,
                              Cache.NoSlidingExpiration, CacheItemPriority.High, null);
}

public DataSet GetXMLData()
{
    if (HttpRuntime.Cache["myCache"] == null)
    {
        LoadCache();
    }
    return (DataSet)HttpRuntime.Cache["myCache"];
}

public void GetData()
{
    DataView dv = GetXMLData().Tables[0].DefaultView;
    dv.RowFilter = "key=0";
    DataTable dtTemp = dv.ToTable();
    dtTemp.Columns.Add("sort");
}

private void SomeFunction()
{
    // Call GetData several times.
    GetData();
    GetData();
    GetData();
}

As I don't know the structure of your dataset, I cannot do much more testing.
There are also other differences that might be a factor.

saxenaabhi6 · Answer 2 · 2014-09-01T21:11:00

Solution 2

set

HttpRuntime.Cache["myCache"] = null;

after adding a column.

Posted 1-Sep-14 21:11pm

saxenaabhi6

Comments

ChintanShukla 2-Sep-14 4:18am

If I do so then every time it will call LoadCache() and hence Read XML on every page load. Then whats the point using cache. I can Directly write loadXML on pageload. I want to use caching to avoid xml read every time.