Webapi+ef (Increase and deletion check)

First, model establishes the ADO entity model.

The second part, controller to establish and delete the method of modification

public static Httpresponsemessage ToJson (Object obj)
{
String str;
if (obj is String | | obj is CHAR)
{
str = obj. ToString ();
}
Else
{
JavaScriptSerializer serializer = new JavaScriptSerializer ();
str = serializer. Serialize (obj);
}
Httpresponsemessage result = new Httpresponsemessage {Content = new stringcontent (str, encoding.getencoding ("UTF-8"), " Application/json ")};
return result;
}

Public Httpresponsemessage Get ()
{

var JG = Db.user.ToList ();
Return ToJson (JG);

}

protected override void Dispose (bool disposing)
{
Db. Dispose ();
Base. Dispose (disposing);
}

Connect database: vs interface to the left of Server Explorer, connect to database, modify or add in Web. config

<connectionStrings>
<add name= "defaultconnection" providername= "System.Data.SqlClient" connectionstring= "Data source= (LocalDb) \ V11.0;initial catalog=aspnet-webapitest1-20170420100509;integrated Security=sspi; attachdbfilename=| Datadirectory|\aspnet-webapitest1-20170420100509.mdf "/>
<add name= "testdbentities" connectionstring= "metadata=res://*/models.model1.csdl|res://*/models.model1.ssdl| Res://*/models.model1.msl;provider=system.data.sqlclient;provider connection String=&quot;data source=.; Initial catalog=testdb;persist security Info=true;user Id=sa; password=123456; Multipleactiveresultsets=true; app=entityframework&quot; "providername=" System.Data.EntityClient "/>
</connectionStrings>

Part III: View View page index.cshtml

@{
Layout = null;
}
<script src= "~/scripts/jquery-1.7.1.min.js" ></script>
<table id= "customertable" border= "0" cellpadding= "3" >
<tr>
<th>UserID</th>
<th>login</th>
<th>pwd</th>
<th>Actions</th>
</tr>
<tr>
<td>
<input type= "text" id= "Txtcustomerid" size= "5"/>
</td>
<td>
<input type= "text" id= "Txtcompanyname"/>
</td>
<td>
<input type= "text" id= "Txtcontactname"/>
</td>
<td>
<input type= "button" Name= "Btninsert" value= "Insert"/>
</td>
</tr>
</table>
<script type= "Text/javascript" >
$ (function () {
$.getjson ("Api/user", loadcustomers);
});
function LoadCustomers (data) {
$ ("#customerTable"). Find ("TR:GT (1)"). Remove ();
$.each (data, function (key, Val) {
var tableRow = ' <tr> ' + ' <td> ' + val.userid + ' </td> ' +
' <td><input type= ' text "value=" ' + Val.login + ' "/></td> ' +
' <td><input type= ' text "value=" ' + val.pwd + ' "/></td> ' +
' <td><input type= ' button ' name= ' btnupdate ' value= ' modify '/> ' +
' <input type= ' button ' name= ' btndelete ' value= ' delete '/></td> ' +
' </tr> ';
$ (' #customerTable '). Append (TableRow);
});
$ ("Input[name= ' Btninsert ']"). Click (OnInsert);
$ ("Input[name= ' btnupdate ']"). Click (OnUpdate);
$ ("Input[name= ' Btndelete ']"). Click (OnDelete);
}
function OnInsert () {
var userId = $ ("#txtCustomerId"). Val ();
var login = $ ("#txtCompanyName"). Val ();
var pwd = $ ("#txtContactName"). Val ();
var data = ' {' userid ': ' + userid + ', ' login ': ' + login + ', ' pwd ': ' + pwd + '}} ';
$.ajax ({
Type: ' POST ',
URL: '/api/user ',
Data:data,
ContentType: "Application/json; Charset=utf-8 ",
DataType: ' JSON ',
Success:function (Result) {
$ ("#txtCustomerId"). Val (');
$ ("#txtCompanyName"). Val (');
$ ("#txtContactName"). Val (');
$ ("#txtCountry"). Val (');
$.getjson ("Api/user", loadcustomers);
Alert (' Customer Added! ');
}
}). Fail (
function (XHR, textstatus, err) {
Alert (' Add failed for the following reason: ' + err);
});

}
function OnUpdate () {

var userId = $ (this). Parent (). Parent (). Children (). Get (0). InnerHTML;

var login = $ (this). Parent (). Parent (). Children (). Get (1)). Find ("Input"). Val ();

var pwd = $ (this). Parent (). Parent (). Children (). Get (2)). Find ("Input"). Val ();


var data = ' {' userid ': ' + userid + ', ' login ': ' + login + ', ' pwd ': ' + pwd + '}} ';

$.ajax ({
Type: ' PUT ',
URL: '/api/user/' + userId,
Data:data,
ContentType: "Application/json; Charset=utf-8 ",
DataType: ' JSON ',
Success:function (Results) {
$.getjson ("Api/user", loadcustomers);
Alert (' Customer Updated! ');
}
}). Fail (function (XHR, textstatus, err) {
Alert (' Failed update! The reason is: ' + err);
});
}

function OnDelete () {
var userId = $ (this). Parent (). Parent (). Children (). Get (0). InnerHTML;
$.ajax ({
Type: ' DELETE ',
URL: '/api/user/' + userId,
ContentType: "Application/json; Charset=utf-8 ",
DataType: ' JSON ',
Success:function (Results) {
$.getjson ("Api/user", loadcustomers);
Alert (' Customer deleted! ');
}
}). Fail (function (XHR, textstatus, err) {
Alert ("Delete Error! The reason is: "+ err);
});

}
</script>

Webapi+ef (Increase and deletion check)