I'm using EF4 and have created POCO objects. The problem with POCO objects are all the entity graph are ICollection....therefore cannot be serialized. I have solved the issues of passing POCO object via WCF.
The problem lies is passing the entity graph to stored procedure....therefore the approach i have take is to convert the entity graph to dataset, convert the dataset to xml and then pass it the stored procedure....this is the only way i could get a clean XML in my stored procedure.
I'm trying to create a generic helper method to convert entity graph to dataset.
public static DataSet ObjectToDataSet<T>(IEnumerable<T> varList)
{
DataSet ds = new DataSet();
if (varList == null)
return ds;
ObjectToDataTable(varList, ds);
return ds;
}
public static void ObjectToDataTable<T>(IEnumerable<T> varlist, DataSet ds)
{
if (varlist == null)
return;
// column names
PropertyInfo[] oProps = null;
string tableName = typeof(T).Name;
bool tableExits = ds.Tables.Contains(tableName);
DataTable dt = new DataTable();
//check if table exits in the dataset
if (!tableExits)
{
dt = new DataTable(typeof(T).Name);
ds.Tables.Add(dt);
oProps = ((Type)varlist.First().GetType()).GetProperties();
foreach (PropertyInfo pi in oProps)
{
Type colType = pi.PropertyType;
if (!colType.IsGenericType)
{
if (colType != typeof(EntityKey))
dt.Columns.Add(new DataColumn(pi.Name, colType));
}
else
if ((colType.IsGenericType) && (colType.GetGenericTypeDefinition() == typeof(Nullable<>)))
dt.Columns.Add(new DataColumn(pi.Name, colType.GetGenericArguments()[0]));
else
if (pi.PropertyType.GetGenericTypeDefinition() == typeof(ICollection<>))
{
//do nothing
}
}
}
if (tableExits)
dt = ds.Tables[tableName];
foreach (T rec in varlist)
{
DataRow dr = dt.NewRow();
foreach (PropertyInfo pi in oProps)
{
if (pi.PropertyType.Namespace != typeof(System.Collections.Generic.ICollection<>).Namespace)
dr[pi.Name] = pi.GetValue(rec, null) == null ? DBNull.Value : pi.GetValue(rec, null);
else
{
Type type = pi.PropertyType.GetGenericArguments()[0];
//this would be a recuresive method
//how to get the Type T and the values to pass to method ObjectToDataTable
//need help here
ObjectToDataTable<
}
}
dt.Rows.Add(dr);
}
}
Take a look at this post.
It deals with the POCO serialization, hope this is what you need.
And this post seems to solve your initial problem.
Related
how I can update a single value for an already existing row in the db by only having a parameters that I want to add it to this attribute
here is my code for a trivial way but didnt work
public bool BuyBook(int BookId, int UserId, int BookPrice){
using (var ctx = new OnlineBooksEntities())
{
User updatedCustomer = (from c in ctx.Users
where c.UserId == UserId
select c).FirstOrDefault();
updatedCustomer.Balance = BookPrice;
ctx.SaveChanges();
}
this.DeleteBook(BookId);
return true;
}
Add an sql query to the method solves the update aim
public bool BuyBook(int BookId, int UserId, int BookPrice)
{
try
{
using (var ctx = new OnlineBooksEntities())
{
User user = ctx.Users.Where(x => x.UserId == UserId).FirstOrDefault();
BookPrice = (int)user.Balance + BookPrice;
int noOfRowUpdated =
ctx.Database.ExecuteSqlCommand("Update Users set Balance = "+BookPrice+ " where UserId ="+UserId);
}
Updating basically means changing an existing row's value. Since you mentioned EF, you can do this by retrieving the object, changing its value, and saving it back. Thus you can do something like this:
using (var db = new MyContextDB())
{
var result = db.Books.SingleOrDefault(b => b.BookPrice == bookPrice);
if (result != null)
{
result.SomeValue = "Your new value here";
db.SaveChanges();
}
}
// Inside an action result
tp = dbContext.tp.Single(x => ...);
foreach (Sample sample in tp.samples)
{
if (sample.SampleStatusId == 1)
changeSamplestatus(sample, 2, now); //change samples to on hold
}
dbContext.SaveChanges();
public void changeSamplestatus(Sample sample, int sampleStatus, DateTime now)
{
sample.SampleHistory.Add(new SampleHistory
{
OldStatus = sample.SampleStatusId,
NewStatus = sampleStatus,
});
sample.SampleStatusId = sampleStatus;
}
I have an entity (sample) that I would like to change it status.
I am calling a function to do so, but the entity doesn't get modified (but it is creating a new row in history table with the correct FK).
It doesn't throw any errors when SaveChanges is called. It just doesn't modify the entity.
You can try:
//INSIDE AN ACTION RESULT
var tp = dbContext.tp.SingleOrDefault(x => ...);
if (tp != null)
{
foreach (Sample sample in tp.samples)
{
if (sample.SampleStatusId == 1)
changeSamplestatus(sample, 2, DateTime.Now);
}
int flag = dbContext.SaveChanges();
if (flag > 0)
{
// update successful
}
}
public void changeSamplestatus(Sample sample, int sampleStatus, DateTime now)
{
//sample.SampleHistory.Add(new SampleHistory
//{
// OldStatus = sample.SampleStatusId,
// NewStatus = sampleStatus,
//});
sample.SampleStatusId = sampleStatus;
}
Don't use Single for this case, because it would throw exception if no result was found or there were more than 1 result. Use SingleOrDefault or FirstOrDefault instead.
You can try this . I hope thiw will work . The Idea is to get the history records first in the context and then update the propterties and set state to mofifed . Please try I didnt tested it but it should work.
public void changeSamplestatus(Sample sample, int sampleStatus, DateTime now)
{
var historyRecordToUpdate = db.SampleHistory.FirstOrDefault(h=>h.id == sampleHistoryId )
if(historyRecordToUpdate !=null )
{
db.Entry(sample).State= EntityState.Modified;
sample.SampleStatusId = sampleStatus;
}
}
I Create A News Site With MVC5 But I Have Problem .
in Model i Create A Repository Folder And in this i Create Rep_Setting for
Connect to Tbl_Setting in DataBase .
public class Rep_Setting
{
DataBase db = new DataBase();
public Tbl_Setting Tools()
{
try
{
var qGetSetting = (from a in db.Tbl_Setting
select a).FirstOrDefault();
return qGetSetting;
}
catch (Exception)
{
return null;
}
}
}
And i Create a Rep_News for Main Page .
DataBase db = new DataBase();
Rep_Setting RSetting = new Rep_Setting();
public List<Tbl_News> GetNews()
{
try
{
List<Tbl_News> qGetNews = (from a in db.Tbl_News
where a.Type.Equals("News")
select a).OrderByDescending(s => s.ID).Skip(0).Take(RSetting.Tools().CountNewsInPage).ToList();
return qGetNews;
}
catch (Exception ex)
{
return null;
}
}
But This Code Have Error to Me
OrderByDescending(s=>s.ID).Skip(0).Take(RSetting.Tools().CountNewsInPage).ToList();
Error :
Error 18 'System.Linq.IQueryable<NewsSite.Models.Domain.Tbl_News>' does
not contain a definition for 'Take' and the best extension method overload
'System.Linq.Queryable.Take<TSource>(System.Linq.IQueryable<TSource>, int)' has
some invalid arguments
E:\MyProject\NewsSite\NewsSite\Models\Repository\Rep_News.cs 50 52 NewsSite
How i Resolve it ?
Try it this way. The plan of debugging is to split your execution, this also makes for a more reusable method in many cases. And a good idea is to avoid using null and nullables if you can, if you use them "on purpose" the you must have a plan for them.
DataBase db = new DataBase();
Rep_Setting RSetting = new Rep_Setting();
public List<Tbl_News> GetNews()
{
int skip = 0;
Tbl_Setting tools = RSetting.Tools();
if(tools == null){ throw new Exception("Found no rows in the database table Tbl_Setting"); }
int? take = tools.CountNewsInPage;//Nullable
if(!take.HasValue)
{
// Do you want to do something if its null maybe set it to 0 and not null
take = 0;
}
string typeStr = "News";
List<Tbl_News> qGetNews = (from a in db.Tbl_News
where a.Type.Equals(typeStr)
select a).OrderByDescending(s => s.ID).Skip(skip).Take(take.Value);
return qGetNews.ToList();
}
if qGetNews is a empty list you now don't break everything after trying to iterate on it, like your return null would. instead if returning null for a lit return a new List<>() instead, gives you a more resilient result.
So I said reusable method, its more like a single action. So you work it around to this. Now you have something really reusable.
public List<Tbl_News> GetNews(string typeStr, int take, int skip = 0)
{
List<Tbl_News> qGetNews = (from a in db.Tbl_News
where a.Type.Equals(typeStr)
select a).OrderByDescending(s => s.ID).Skip(skip).Take(take);
return qGetNews.ToList();
}
Infact you shjould always try to avoid returning null if you can.
public class Rep_Setting
{
DataBase db = new DataBase();
public Tbl_Setting Tools()
{
var qGetSetting = (from a in db.Tbl_Setting
select a).FirstOrDefault();
if(qGetSetting == null){ throw new Exception("Found no rows in the database table Tbl_Setting"); }
return qGetSetting;
}
}
I've got a complex form on a page that is bound to a POCO representing a rather complex entity. One of the requirements is that, on blur, I update the database.
I'm currently passing the property (as key), value, and CampaignId via ajax. The key might look something like: Campaign.FanSettings.SocialSharing.FacebookLinkText.
I am using the code below, and getting "close". My final propertyToSet is the FacebookLinkText is not being set, because my object source is of type Entities.Campaign, while my object value is simply a string. I understand these need to be the same type, but I don't understand how to do that. Two questions:
How do I modify the code below to be able to execute the propertyToSet.SetValue method
Since I'm casting this to an object, I don't see how this would actually update my entity, so when I call SaveChanges it updates appropriately. What am I missing?
Thanks!
Code:
public void UpdateCampaign(int id, string key, string value)
{
using (var context = new BetaEntities())
{
var camp = context.Campaigns.Where(e => e.Id == id).Single();
SetProperty(camp, key,value);
}
}
public void SetProperty(object source, string property, object value)
{
string[] bits = property.Split('.');
for (int i = 0; i < bits.Length - 1; i++)
{
PropertyInfo prop = source.GetType().GetProperty(bits[i]);
source = prop.GetValue(source, null);
}
PropertyInfo propertyToSet = null;
if (source is IEnumerable)
{
foreach (object o in (source as IEnumerable))
{
propertyToSet = o.GetType().GetProperty(bits[bits.Length - 1]);
break;
}
}
else
{
propertyToSet = source.GetType().GetProperty(bits[bits.Length - 1]);
}
propertyToSet.SetValue(source, value, null);
}
Solved.
public void UpdateCampaign(int id, string key, string value)
{
using (var context = new BetaEntities())
{
var camp = context.Campaigns.Where(e => e.Id == id).Single();
SetProperty(camp, key, value);
context.SaveChanges()
}
}
public void SetProperty(object source, string property, object value)
{
string[] bits = property.Split('.');
for (int i = 0; i < bits.Length - 1; i++)
{
PropertyInfo prop = source.GetType().GetProperty(bits[i]);
source = prop.GetValue(source, null);
}
PropertyInfo propertyToSet = null;
if (source is IEnumerable)
{
foreach (object o in (source as IEnumerable))
{
propertyToSet = o.GetType().GetProperty(bits[bits.Length - 1]);
propertyToSet.SetValue(o, value,null);
break;
}
}
else
{
propertyToSet = source.GetType().GetProperty(bits[bits.Length - 1]);
propertyToSet.SetValue(source, value, null);
}
}
I want to create a method which can takes the properties I possibly may update and leaving those not interested untouched.
Here is what I did:
public static void updateTable(int id, string field1, string field2, string field3){
using(var context = new Entities()){
var obj = context.Table.Where(x=>x.id == id).FirstOrDefault();
if(obj != null){
obj.field1 = field1;
...
obj.SaveChanges();
}
}
}
But in this pattern, I need to pass all 4 parameters into the method even I just want to update only one field. Is there any generic solution to update only the fields I passed in?
I came up something like this:
public static void updateTable(int id, object data_json){
using(var context = new Entities()){
var obj = context.Table.Where(x=>x.id == id).FirstOrDefault();
if(obj != null){
if(data_json['field1']!=null) //something like this
obj.field1 = data_json['field1'];
...
obj.SaveChanges();
}
}
}
But this can't handle the case that I do want to set a field to be null. Or is there any better solution?
If you don't care about updating relationships, you can use ApplyCurrentValues, which only updates the scalar properties.
E.g:
public static void updateTable(int id, object data_json){
using(var context = new Entities()) {
var obj = context.Table.Where(x=>x.id == id).FirstOrDefault();
context.ApplyCurrentValues("Table", data_json);
}
}
It assumes an entity with the same key is already attached in the graph. In this case, the query for var obj will ensure the object is in the graph, then it's contents are overridden with the scalar properties on the supplied object.
You might need an explicit cast on data_json to ensure it is of the same type contained in the entity set.
Using an ExpandoObject would allow you to send in only the properties you want to set, and would allow you to specify null values as well.
For example:
public static void updateTable(int id, dynamic data){
using(var context = new Entities()){
var obj = context.Table.Where(x=>x.id == id).FirstOrDefault();
if(obj != null){
if (((IDictionary<string, object>)data).ContainsKey("field1"))
obj.field1 = data.field1;
...
obj.SaveChanges();
}
}
}
and you could call it like this:
dynamic data = new ExpandoObject();
data.field1 = 123;
data.field2 = null;
data.field5 = "abc";
MyClass.updateTable(1, data);
Everything can be solved with a moment of reflection. This function solves the problem:
public void UpdateTable(int id, object values)
{
using (var entities = new MyEntities())
{
var valuesType = values.GetType();
var element = entities.MyTable.Where(t => t.ID == id).First();
//We are iterating through all properties of updated element and checking
//if there is value provided for there properties in values parameter
foreach (var property in element.GetType().GetProperties())
{
var valuesProperty = valuesType.GetProperty(property.Name);
//If values contain this property
if (valuesProperty != null)
{
//taking value out of values parameter
var value = valuesProperty.GetValue(values, null);
//setting it in our element to update
property.SetValue(element, value, null);
}
}
entities.SaveChanges();
}
}
Usage:
UpdateTable(125, new { FieldA = 1, FieldB = "ABCD" });
You can even make this method more universal by adding generic table type parameter.