c# - How can pass values between events? -

-

i've dropdownlist , button inside datalist. choose number of items dropdownlist , pass button event send database.

but i'm unable so. problem variable selectedvalue gets assigned inside dditem_change, although i've declared globally.

how can access value in datalist1_itemcommand(object source, datalistcommandeventargs e).

here code dropdown list change

public void dditem_change(object sender, eventargs e)     {         var ddllist = (dropdownlist)sender;         selectedvalue = ((dropdownlist)ddllist.namingcontainer.findcontrol("drplist")).selectedvalue;     }

this code public void datalist1_itemcommand

public void datalist1_itemcommand(object source, datalistcommandeventargs e) {     if(e.commandname == "add")     {         if (session["user"] == null)         {             response.write("<script>alert('login first!!!');</script>");          }         else         {              string[] ar = e.commandargument.tostring().split(',');             sqlconnection con = new sqlconnection();             con.connectionstring = "data source=dtpxp-77a;initial catalog=practice;integrated security=true";             con.open();             sqlcommand cmd = new sqlcommand("insert cart values(@username,@prodname,@price,@stock)", con);             cmd.parameters.add("@username", sqldbtype.varchar);             cmd.parameters.add("@prodname", sqldbtype.varchar);             cmd.parameters.add("@price", sqldbtype.int);             cmd.parameters.add("@stock", sqldbtype.int);             cmd.parameters["@username"].value = session["user"].tostring();             cmd.parameters["@prodname"].value = ar[0].tostring();             cmd.parameters["@price"].value = int.parse(ar[1]);             cmd.parameters["@stock"].value = //selectedvalue not accessible//             cmd.executenonquery();             response.write("<script>alert('successfully added');</script>");          }     } }

this result of asp.net page lifecycle. when select drop down menu causes postback in store selectedvalue variable. when trigger button causes another postback results in selectedvalue being lost page re-created.

in order persist value between postbacks need store somewhere. example, use session storage e.g.

protected void page_load(object sender, eventargs e) {     if (!page.ispostback)     {         selectedvalue = (string)session["selectedvalue"];     } }  public void dditem_change(object sender, eventargs e) {     var ddllist = (dropdownlist)sender;     session["selectedvalue"] = ((dropdownlist)ddllist.namingcontainer.findcontrol("drplist")).selectedvalue; }  public void datalist1_itemcommand(object source, datalistcommandeventargs e) {     // selectedvalue should accessible }

considering how small data is, , given in-fact view specific, might better placed in viewstate.


Comments

Post a Comment

Popular posts from this blog

c# - How Configure Devart dotConnect for SQLite Code First? -

-
can configure following sample code ? when run following code, error : no entity framework provider found ado.net provider invariant name 'devart.data.sqlite' setting in machine.config <system.data> <dbproviderfactories> <add name="dotconnect sqlite" invariant="devart.data.sqlite" description="devart dotconnect sqlite" type="devart.data.sqlite.sqliteproviderfactory, devart.data.sqlite, version=4.6.287.0, culture=neutral, publickeytoken=09af7300eec23701" /> </dbproviderfactories> </system.data> after add below block code in app.config <?xml version="1.0"?> <configuration>   <configsections> <!-- more information on entity framework configuration, visit http://go.microsoft.com/fwlink/?linkid=237468 --> <section name="entityframework" type="system.data.entity.internal.configfile.entityframeworksection, entit...
Read more

c++ - Clear the memory after returning a vector in a function -

-
i have function processes , stores lot of data in , returns results vector of class. amount of data stored in function tremendous , want clear storage memory of function after finished job. necessary (does function automatically clear memory) or should clear memory function? update: vector<customers> process(char* const *filename, vector<int> id) { vector<customers> list_of_customers; (perform actions) return list_of_customers; } variables defined locally within function automatically released @ end of function scope. destructors objects called, should free memory allocated objects (if objects coded correctly). example of such object std::vector . anything you've allocated new must have corresponding delete release storage. try avoid doing own allocation , use raii instead, i.e. containers or smart pointers.
Read more

erlang - Saving a digraph to mnesia is hindered because of its side-effects -

-
updated the digraph library in erlang implements data type side-effectful. each operation on data type saves new state in ets table -- instead of returning altered version of itself, more common in functional languages. the problem usage perspective, impedes effort store or pass around state in convenient way requiring me first "collect" state before can start juggle around. the closest solution have seen far serializer/deserializer , these have drawback tied current structure of digraphs instead of operating on abstract type -- prevents future proof solution. update pascal pointed out serializer utilizes interface of digraph, , hence eliminates drawback mentioned above. better, albeit still inconvenient, see no better alternative. what recommendation on how store digraphs? should go different data type altogether? thanks. i not sure understand concern. fact digraph stored in ets transparent in user interface, might want chnge either exchange digr...
Read more