I am using BeanItemContainer for my Grid. I want to get a unique list of one of the properties. For instance, let's say my beans are as follows:
class Fun {
String game;
String rules;
String winner;
}
This would display as 3 columns in my Grid. I want to get a list of all the unique values for the game property. How would I do this? I have the same property id in multiple different bean classes, so it would be nice to get the values directly from the BeanItemContainer. I am trying to avoid building this unique list before loading the data into the Grid, since doing it that way would require me to handle it on a case by case basis.
My ultimate goal is to create a dropdown in a filter based on those unique values.
There isn't any helper for directly doing what you ask for. Instead, you'd have to do it "manually" by iterating through all items and collecting the property values to a Set which would then at the end contain all unique values.
Alternatively, if the data originates from a database, then you could maybe retrieve the unique values from there by using e.g. the DISTINCT keyword in SQL.
In case anyone is curious, this is how I applied Leif's suggestion. When they enter the dropdown, I cycle through all the item ids for the property id of the column I care about, and then fill values based on that property id. Since the same Grid can be loaded with new data, I also have to "clear" this list of item ids.
filterField.addFocusListener(focus->{
if(!(filterField.getItemIds() instanceof Collection) ||
filterField.getItemIds().isEmpty())
{
BeanItemContainer<T> container = getGridContainer();
if( container instanceof BeanItemContainer && getFilterPropertyId() instanceof Object )
{
List<T> itemIds = container.getItemIds();
Set<String> distinctValues = new HashSet<String>();
for(T itemId : itemIds)
{
Property<?> prop = container.getContainerProperty(itemId, getFilterPropertyId());
String value = null;
if( prop.getValue() instanceof String )
{
value = (String) prop.getValue();
}
if(value instanceof String && !value.trim().isEmpty())
distinctValues.add(value);
}
filterField.addItems(distinctValues);
}
}
});
Minor point: the filterField variable is using the ComboBoxMultiselect add-on for Vaadin 7. Hopefully, when I finally have time to convert to Vaadin 14+, I can do something similar there.
Related
This query produces an error No value given for one or more required parameters:
using (var conn = new OleDbConnection("Provider=..."))
{
conn.Open();
var result = conn.Query(
"select code, name from mytable where id = ? order by name",
new { id = 1 });
}
If I change the query string to: ... where id = #id ..., I will get an error: Must declare the scalar variable "#id".
How do I construct the query string and how do I pass the parameter?
The following should work:
var result = conn.Query(
"select code, name from mytable where id = ?id? order by name",
new { id = 1 });
Important: see newer answer
In the current build, the answer to that would be "no", for two reasons:
the code attempts to filter unused parameters - and is currently removing all of them because it can't find anything like #id, :id or ?id in the sql
the code for adding values from types uses an arbitrary (well, ok: alphabetical) order for the parameters (because reflection does not make any guarantees about the order of members), making positional anonymous arguments unstable
The good news is that both of these are fixable
we can make the filtering behaviour conditional
we can detect the category of types that has a constructor that matches all the property names, and use the constructor argument positions to determine the synthetic order of the properties - anonymous types fall into this category
Making those changes to my local clone, the following now passes:
// see https://stackoverflow.com/q/18847510/23354
public void TestOleDbParameters()
{
using (var conn = new System.Data.OleDb.OleDbConnection(
Program.OleDbConnectionString))
{
var row = conn.Query("select Id = ?, Age = ?", new DynamicParameters(
new { foo = 12, bar = 23 } // these names DO NOT MATTER!!!
) { RemoveUnused = false } ).Single();
int age = row.Age;
int id = row.Id;
age.IsEqualTo(23);
id.IsEqualTo(12);
}
}
Note that I'm currently using DynamicParameters here to avoid adding even more overloads to Query / Query<T> - because this would need to be added to a considerable number of methods. Adding it to DynamicParameters solves it in one place.
I'm open to feedback before I push this - does that look usable to you?
Edit: with the addition of a funky smellsLikeOleDb (no, not a joke), we can now do this even more directly:
// see https://stackoverflow.com/q/18847510/23354
public void TestOleDbParameters()
{
using (var conn = new System.Data.OleDb.OleDbConnection(
Program.OleDbConnectionString))
{
var row = conn.Query("select Id = ?, Age = ?",
new { foo = 12, bar = 23 } // these names DO NOT MATTER!!!
).Single();
int age = row.Age;
int id = row.Id;
age.IsEqualTo(23);
id.IsEqualTo(12);
}
}
I've trialing use of Dapper within my software product which is using odbc connections (at the moment). However one day I intend to move away from odbc and use a different pattern for supporting different RDBMS products. However, my problem with solution implementation is 2 fold:
I want to write SQL code with parameters that conform to different back-ends, and so I want to be writing named parameters in my SQL now so that I don't have go back and re-do it later.
I don't want to rely on getting the order of my properties in line with my ?. This is bad. So my suggestion is to please add support for Named Parameters for odbc.
In the mean time I have hacked together a solution that allows me to do this with Dapper. Essentially I have a routine that replaces the named parameters with ? and also rebuilds the parameter object making sure the parameters are in the correct order.
However looking at the Dapper code, I can see that I've repeated some of what dapper is doing anyway, effectively it each parameter value is now visited once more than what would be necessary. This becomes more of an issue for bulk updates/inserts.
But at least it seems to work for me o.k...
I borrowed a bit of code from here to form part of my solution...
The ? for parameters was part of the solution for me, but it only works with integers, like ID. It still fails for strings because the parameter length isn't specifed.
OdbcException: ERROR [HY104] [Microsoft][ODBC Microsoft Access Driver]Invalid precision value
System.Data.Odbc. OdbcParameter.Bind(OdbcStatementHandle hstmt,
OdbcCommand command, short ordinal, CNativeBuffer parameterBuffer, bool allowReentrance)
System.Data.Odbc.OdbcParameterCollection.Bind(OdbcCommand command, CMDWrapper cmdWrapper, CNativeBuffer parameterBuffer)
System.Data.Odbc.OdbcCommand.ExecuteReaderObject(CommandBehavior behavior, string method, bool needReader, object[] methodArguments, SQL_API odbcApiMethod)
System.Data.Odbc.OdbcCommand.ExecuteReaderObject(CommandBehavior behavior, string method, bool needReader)
System.Data.Common.DbCommand.ExecuteDbDataReaderAsync(CommandBehavior behavior, CancellationToken cancellationToken)
Dapper.SqlMapper.QueryAsync(IDbConnection cnn, Type effectiveType, CommandDefinition command) in SqlMapper.Async.cs
WebAPI.DataAccess.CustomerRepository.GetByState(string state) in Repository.cs
var result = await conn.QueryAsync(sQuery, new { State = state });
WebAPI.Controllers.CustomerController.GetByState(string state) in CustomerController .cs
return await _customerRepo.GetByState(state);
For Dapper to pass string parameters to ODBC I had to specify the length.
var result = await conn.QueryAsync<Customer>(sQuery, new { State = new DbString { Value = state, IsFixedLength = true, Length = 4} });
so I have a form with several fields which are criteria for searching in a database.
I want to formulate a query using LINQ like so:
var Coll = (from obj in table where value1 = criteria1 && value2 = criteria2...)
and so on.
My problem is, I don't want to write it using If statements to check if every field has been filled in, nor do I want to make separate methods for the various search cases (criteria 1 and criteria 5 input; criteria 2 and criteria 3 input ... etc.)
So my question is: How can I achieve this without writing an excessive amount of code? If I just write in the query with comparison, will it screw up the return values if the user inputs only SOME values?
Thanks for your help.
Yes, it will screw up.
I would go with the ifs, I don't see what's wrong with them:
var query = table;
if(criteria1 != null)
query = query.Where(x => x.Value1 == criteria1);
if(criteria2 != null)
query = query.Where(x => x.Value2 == criteria2);
If you have a lot of criteria you could use expressions, a dictionary and a loop to cut down on the repetitive code.
In an ASP.NET MVC app, chances are your user input is coming from a form which is being POSTed to your server. In that case, you can make use of strongly-typed views, using a viewmodel with [Required] on the criteria that MUST be provided. Then you wrap your method in if (ModelState.IsValid) { ... } and you've excluded all the cases where the user hasn't given you something they need.
Beyond that, if you can collect your criteria into a list, you can filter it. So, you could do something like this:
filterBy = userValues.Where(v => v != null);
var Coll = (from obj in table where filterBy.Contains(value1) select obj);
You can make this more complex by having a Dictionary (or Lookup for non-unique keys) that contains a user-entered value along with some label (an enum, perhaps) that tells you which field they're filtering by, and then you can group them by that label to separate out the filters for each field, and then filter as above. You could even have a custom SearchFilter object that contains other info, so you can have filters with AND, NOT and OR conditions...
Failing that, you can remember that until you trigger evaluation of an IQueryable, it doesn't hit the database, so you can just do this:
var Coll = (from obj in table where value1 == requiredCriteria select obj);
if(criteria1 != null)
{
query = query.Where(x => x.Value1 == criteria1);
}
//etc...
if(criteria5 != null)
{
query = query.Where(x => x.Value5 == criteria5);
}
return query.ToList();
That first line applies any criteria that MUST be there; if there aren't any mandatory ones then it could just be var Coll = table;.
That will add any criteria that are provided will be applied, any that aren't will be ignored, you catch all the possible combinations, and only one query is made at the end when you .ToList() it.
As I understand of your question you want to centralize multiple if for the sake of readability; if I were right the following would be one of some possible solutions
Func<object, object, bool> CheckValueWithAnd = (x, y) => x == null ? true : x==y;
var query = from obj in table
where CheckValue(obj.value1, criteria1) &&
CheckValue(obj.value2, criteria2) &&
...
select obj;
It ls flexible because in different situations or scenarios you can change the function in the way that fulfill your expectation and you do not need to have multiple if.
If you want to use OR operand in your expression you need to have second function
Func<object, object, bool> CheckValueWithOr = (x, y) => x == null ? false : x==y;
I'm working on speed issues with a currently working method that finds a specific attribute collection within an ArrayList. Depending on the size, it can take longer than 7 seconds to find the value in the list.
I need to speed up this process, so I can deal with larger volumes of data. Any assistance would be greatly appreciated. Here is my example;
Method:
public ArrayList getIntegrationTag(String attribute) {
return crmMapping?.findAll { it.get("ATTRIBUTE") == attribute }?.collect{
it.INTEGRATION_TAG
}?.unique()
}//end getIntegrationTag(String attribute)
crmMapping content
"[{ATTRIBUTE=AcademicIndex, INTEGRATION_TAG=Contact~nAcademic_Index},
{ATTRIBUTE=AcademicInterest,
INTEGRATION_TAG=Contact~msplAcademic_Interest},........]"
the findAll loops over each record, then the collect loops over each record, then unique loops over each record again.
Try...
Set result = [] as Set
for(element in crmMapping) {
if(element.get("ATTRIBUTE") == attribute) {
result << element.INTEGRATION_TAG
}
}
return (result as ArrayList)
This will only loop once it it will be unique as it was added to a Set
Do the following once
def crmMappingMap = crmMapping.groupBy({ it.ATTRIBUTE })
Then you have a map of all same attribute instances and can access it using crmMappingMap[attribute].INTEGRATION_TAG, which will return the desired array, like this:
public ArrayList getIntegrationTag(String attribute) {
crmMappingMap[attribute].INTEGRATION_TAG.unique()
}
Always keep a map, then speed of access will be fast enough.
I have a listview that I fill from an Adapter. My original code the data was being returned from a table, but now I need to get the code from a query with a join so the examples I used will no longer work and I haven't been able to find out how to use a query for this. I'm using an ORMrepository.
In my ORMrepository I have this function
public IList<Coe> GetmyCoe()
{
using (var database = new SQLiteConnection(_helper.WritableDatabase.Path))
{
string query = "SELECT Coe.Id, Adult.LName + ', ' + Adult.MName AS Name, Coe.Createdt FROM Adult INNER JOIN Coe ON Adult.CoeMID = Coe.Id";
return database.Query<Coe>(query);
}
}
which actually returns the data I want.
then in my Activity page I have this.
_list = FindViewById<ListView>(Resource.Id.List);
FindViewById<ListView>(Resource.Id.List).ItemClick += new System.EventHandler<ItemEventArgs>(CoeList_ItemClick);
var Coe = ((OmsisMobileApplication)Application).OmsisRepository.GetmyCoe();
_list.Adapter = new CoeListAdapter(this, Coe);
My Adapter page is where I have the problem, I know it is set up to to looking at a table which I'm not doing anymore. But I don't know how to change it for what I'm passing into it now. Current CoeListAdapter is:
public class CoeListAdapter : BaseAdapter
{
private IEnumerable<Coe> _Coe;
private Activity _context;
public CoeListAdapter(Activity context, IEnumerable<Coe> Coe)
{
_context = context;
_Coe = Coe;
}
public override View GetView(int position, View convertView, ViewGroup parent)
{
var view = (convertView
?? _context.LayoutInflater.Inflate(
Resource.Layout.CoeListItem, parent, false)
) as LinearLayout;
var Coe = _Coe.ElementAt(position);
view.FindViewById<TextView>(Resource.Id.CoeMID).Text = Coe.Id.ToString();
//view.FindViewById<TextView>(Resource.Id.GrdnMaleName).Text = Coe.Name;
view.FindViewById<TextView>(Resource.Id.CreateDt).Text = Coe.CreateDt;
return view;
}
public override int Count
{
get { return _Coe.Count(); }
}
public Coe GetCoe(int position)
{
return _Coe.ElementAt(position);
}
public override Java.Lang.Object GetItem(int position)
{
return null;
}
public override long GetItemId(int position)
{
return position;
}
}
How do I set up the CoeListAdapter.cs page so that it can use the passed in data. As you can see I have a commented out lines where I fill a TextView which error because Coe.Name is not in the table model for Coe. but it is returned in the query. I believe my problem is IEnumerable but what do I change it to. I'm new to Mobile developement and suing VS2010 for Mono
The problem probably lies with the binding/mapping of the object not the creation of the view.
Or probably more specifically, the query.
Adult.LName + ', ' + Adult.MName AS Name
this should be:
Adult.LName || ', ' || Adult.MName AS Name
See also: String concatenation does not work in SQLite
From the sqlite docs: http://www.sqlite.org/lang_expr.html under the Operators heading:
The unary operator + is a no-op. It can be applied to strings,
numbers, blobs or NULL and it always returns a result with the same
value as the operand.
Note that there are two variations of the equals and not equals
operators. Equals can be either = or ==. The non-equals operator can
be either != or <>. The || operator is "concatenate" - it joins
together the two strings of its operands. The operator % outputs the
value of its left operand modulo its right operand.
The result of any binary operator is either a numeric value or NULL,
except for the || concatenation operator which always evaluates to
either NULL or a text value.
This shows that the + will evaluate to zero. If you use ||, the value will either be the correct value or NULL (if either of Adult.LName or Adult.MName is NULL).
This can be fixed by:
coalesce(first, '') || ', ' || coalesce(second, '')
but this may result in , LastName or FirstName,.
Another way would be to create another two properties in Coe called LName and MName.
Then bind the values to those properties and use the Name property like this:
public string Name
{
get { return string.Join(", ", LName, MName); }
}
This will probably be better as you can change how the Name appears especially if there are different combinations of First, Middle and Last names in different places.
And off topic:
I believe my problem is IEnumerable...
This is probably not too true as it returns the correct values. A better way would be to use IList as IEnumerable will iterate through the list each time to get the item as it does not know that the collection is actually a list. (I think)
thanks for the help on the concantination, I did find that was wrong, I did fix my problem, I was using an example by Greg Shackles on how to set up using a data base. what I had to do was create a new model with the elements I was wanting. So I created a new Model and called it CoeList, then everywhere I had List or IEnumerable I changed it to List or IEnumerable and it worked.
I'm trying to do something similar to this post where I don't pull back all columns from a particular entity, however my framework makes use of inheritence and I lose scope of the entity type after it's been cast to an anonymous type.
The structure of my Entity Framework has a base entity called Action. From here I've created two inherited entities called Event and Activity. I want to pull back the last X Actions and pass them to my strongly typed view which accepts an Action and from there determines if its an Activity or Event and renders the correct partial view.
if(Model.GetType() == typeof(Event))
{
//render Event view
}
else if(Model.GetType() == typeof(Activity))
{
//render Activity view
}
I can pull the last 10 as an anonymous type and then cast:
var result = from a in new DataContext().Actions
where a.UserId == someGuidValue
select new { a.CreatedOn, a.Summary };
List<Action> list = result.AsEnumerable()
.Select(o => new Action {
CreatedOn = o.CreatedOn,
Summary = o.Summary
}).ToList();
However, once I pass the new List of Actions to my strongly typed view it loses scope of whether it's an Activity or an Event since it's been cast as an Action. My question is, without exposing the discriminator column, is there any way to cast each item to the proper type or am I going about this the wrong way?
A bit kludgy, but will work:
var result = from a in new DataContext().Actions
where a.UserId == someGuidValue
let IsEvent = a as Event != null
select new { a.CreatedOn, IsEvent, a.Summary };
List<Action> list = result.AsEnumerable()
.Select(o => o.IsEvent ?
(Action) new Event {
CreatedOn = o.CreatedOn,
Summary = o.Summary
}
: (Action) new Activity {
CreatedOn = o.CreatedOn,
Summary = o.Summary
}
}).ToList();
Example with type-specific columns, presuming that e.EventSpecific is of a nullable type.
var result = from a in new DataContext().Actions
where a.UserId == someGuidValue
let ev = a as Event
let IsEvent = ev != null
select new { a.CreatedOn, IsEvent, a.Summary, ev.EventSpecific };
List<Action> list = result.AsEnumerable()
.Select(o => o.IsEvent ?
(Action) new Event {
CreatedOn = o.CreatedOn,
Summary = o.Summary,
EventSpecific = o.EventSpecific
}
: (Action) new Activity {
CreatedOn = o.CreatedOn,
Summary = o.Summary,
EventSpecific = o.EventSpecific // will be null, but using o.EventSpecific saves casting
}
}).ToList();
If o.EventSpecific is of a non-nullable type, then you must convert it to a nullable type in the L2E query.
You are probably on the wrong way. At first I would assume that Action should be an abstract class and you should not be able to create instances of it at all. If you then only fetch a subset of the properties and the subset does no longer allow to discriminate between events and activities, it is probably the wrong way to try making events and activities out of them.
So it actually seems not to be a technical problem - it should be quite easy to include some discrimination information in the anonymous type - but a design problem. I suggest to rethink if it is required to discriminate the query result and if so if it is really a good idea to discriminate the result in absence of an discriminator.