I want to display all rows from database where row at specified column is empty (data is not inserted). To do that, in my onCreateLoader I wrote following code:
override fun onCreateLoader(p0: Int, p1: Bundle?): Loader<Cursor> {
val projection = arrayOf(
WalletEntry._ID,
WalletEntry.KEY_TITLE,
WalletEntry.KEY_MONEY,
WalletEntry.KEY_LAST_DATE,
WalletEntry.KEY_LAST_EXPENSE,
WalletEntry.KEY_LAST_TRANSACTION_TITLE,
WalletEntry.KEY_LOCALES,
WalletEntry.KEY_CURRENCY
)
val selection = "${WalletEntry.KEY_CURRENCY} = ?"
val selectionArgs = arrayOf("")
return applicationContext?.let { context ->
CursorLoader(context,
WalletEntry.CONTENT_URI,
projection,
selection,
selectionArgs,
null)
}!!
}
Where I want to display all results where WalletEntry.KEY_CURRENCY has no signed value, is empty. I tried to specify selectionArgs as null but it neither worked. So, how am I suppose to write selectionArgs to display all results where given row is empty?
To make my situation more clear I'll provide an app target. I'm learning kotlin and decided to write something like "bank" application where you can add different wallets and specify currencies. If you add a new currency it's being instantly added to the database to the column WalletEntry.KEY_CURRENCY. Then I have a list containing all "wallets", in which after adding a new currency an empty extra wallet appears. To avoid that I want to filter results and display only those, which do not have value passed in WalletEntry.CURRENCY column.
If you're looking for NULL values in that database column, I think you might be looking for:
val selection = "${WalletEntry.KEY_CURRENCY} IS NULL"
val selectionArgs = null
If the selectionArgs argument is not nullable, try setting it to emptyArray<String>()
Related
I'm trying to update a specific row by ID :
fun updateEmployeeInfo(id:Int, firstName:String): Int {
val db = this.writableDatabase
var cv = ContentValues()
cv.put(COL_FIRSTNAME, firstName )
val result = db.update(TABLE_NAME, cv, COL_FIRSTNAME+"=?", arrayOf(firstName))
return result
}
Running this with an ID that already exists in the database it isn't updating.
screenshot of the database
You are saying update the rows with the provided (passed) first name by changing the first name to the very same first name (effectively doing nothing).
I believe that you want to use:-
val result = db.update(TABLE_NAME, cv, COL_ID+"=?", arrayOf(id.toString))
assuming that COL_ID holds the value of the id column name.
or you could use the more concise return db.update(TABLE_NAME, cv, COL_ID+"=?", arrayOf(id.toString))
This is then saying update the row where the id is the provided/passed id changing the first name, whatever it is, to the provided/passed first name.
We have a storage table where we want to add a new integer column (It is in fact an enum of 3 values converted to int). We want a row to be required when:
It is an older row and the column does not exist
It is a new row and the column exists and does not match a particular value
When I just use a not equal operator on the column the old rows do not get returned. How can this be handled?
Update
Assuming a comparison always returns false for the non-existent column I tried somethinglike below (the value of the property will be always > 0 when it exists), which does not work either:
If the (Prop GreaterThanOrEqual -1) condition returns false I assume the value is null.
If not then, the actual comparison happens.
string propNullCondition = TableQuery.GenerateFilterConditionForInt(
"Prop",
QueryComparisons.GreaterThanOrEqual,
-1);
propNullCondition = $"{TableOperators.Not}({propNullCondition})";
string propNotEqualValueCondition = TableQuery.CombineFilters(
propNullCondition,
TableOperators.Or,
TableQuery.GenerateFilterConditionForInt(
"Prop",
QueryComparisons.NotEqual,
XXXX));
Note: The table rows written so far do not have "Prop" and only new rows will have this column. And expectation is the query should return all old rows and the new ones only when Prop != XXXX.
It seems that your code is correct, maybe there is a minor error there. You can follow my code below, which works fine as per my test:
Note: in the filter, the column name is case-sensitive.
CloudTableClient tableClient = storageAccount.CreateCloudTableClient();
CloudTable table = tableClient.GetTableReference("test1");
string propNullCondition = TableQuery.GenerateFilterConditionForInt(
"prop1", //note the column name shoud be case-sensitive here.
QueryComparisons.GreaterThanOrEqual,
-1);
propNullCondition = $"{TableOperators.Not}({propNullCondition})";
TableQuery<DynamicTableEntity> propNotEqualValueCondition = new TableQuery<DynamicTableEntity>()
.Where(
TableQuery.CombineFilters(
propNullCondition,
TableOperators.Or,
TableQuery.GenerateFilterConditionForInt(
"prop1",//note the column name shoud be case-sensitive here.
QueryComparisons.NotEqual,
2)));
var query = table.ExecuteQuery(propNotEqualValueCondition);
foreach (var q in query)
{
Console.WriteLine(q.PartitionKey);
}
The test result:
Here is my table in azure:
Here I have several functions that all just set a single field on a model record.
In a more dynamic language, I'd just have a single setter function and pass it the name of the field (as a string) and the value that I want to set on the model object.
Is there a way to pass the name of the field in Elm?
What's the Elm way of doing something like this?
type alias Patient =
{ id : String
, name : String
, dateOfBirth : String
, sex : String
... other fields
}
setPatientName : Patient -> String -> Patient
setPatientName patient value =
{ patient | name = value }
setPatientDateOfBirth : Patient -> String -> Patient
setPatientDateOfBirth patient value =
{ patient | dateOfBirth = value }
setPatientSex : Patient -> String -> Patient
setPatientSex patient value =
{ patient | sex = value }
... many others
-- idx is the index of the patient in the model (which is an array of patients)
-- UpdateCell is a variant of my Msg type, like this: UpdateCell Int (Patient -> String -> Patient) String
onInputHandler : Int -> (Patient -> String -> Patient) -> String -> Msg
onInputHandler idx setter inputText =
UpdateCell idx setter inputText
-- idx is the index of the patient in the model (which is an array of patients)
createTableRow : Int -> Patient -> Html Msg
createTableRow idx patient =
...
, input [ type_ "text", onInput (onInputHandler idx setPatientName), value patient.name ] []
, input [ type_ "text", onInput (onInputHandler idx setPatientDateOfBirth), value patient.dateOfBirth ] []
...
I'm currently using each of these functions as an event handler for input elements. So I need a function that I can use for handling the input event. Ideally, I'd define just a single function and use that single one for all the input elements and pass it the field I want to update on the patient record.
The short answer is "no". But this seems a bit like an XY problem. It's not clear what benefit you are trying to achieve since the full application of such a function would be longer than the equivalent record update expression:
setField "name" patient value
-- vs
{ patient | name = value }
and as a partially applied function is only slightly shorter than the equivalent anonymous function with shortened argument names:
setField "name"
-- vs
\r x -> { r | name = x }
Although the latter is significantly noisier with all the symbols.
There is also a short-hand function for getting a record field:
.name
-- vs
\r -> r.name
So there is some precedent for having a dedicated syntax for setter functions too, but unfortunately there is not. Likely because it would complicate the language, and the syntax in particular, for relatively little benefit. I'm therefore curious about what you're actually trying to accomplish.
Edit after question update:
Putting functions in the Msg is a very bad idea because it goes against the Elm Architecture. It makes the state transition opaque and won't work very well with the debugger. When something goes wrong you can still see the state before and after, but you'll have trouble understanding what happened, and why it happened, because that information is encoded in an opaque function which probably isn't the one it should be.
You'll also have trouble factoring your logic. If you need something to happen only when a certain field updates, you might have to put the logic in the view, or special-case that field by putting the logic for that in update while the rest is in view, for example. Either way, you're on the path to a messy code base.
You should generally use names for messages that describe what happened, not what to do, because that tends to lead to an imperative mindset. Instead of UpdateCell you could call it InputChanged, for example. Then instead of the function you should have an identifier for the field. Ideally a custom type, like InputChanged Name, but even a string will work, though it will be much easier to miss a typo.
So instead of setter functions for each field you'll just case match the message and set the field in the update function:
InputChanged Name value ->
{ patient | name = value }
-- vs
setPatientName : Patient -> String -> Patient
setPatientName patient value =
{ patient | name = value }
Then if you need to clear the sex when the name changes, for example (because reasons...), you can simply do:
InputChanged Name value ->
{ patient | name = value, sex = "" }
The Elm Architecture is good because it makes changes easy and safe, not because it's concise and free of boiler-plate. Good Elm code often has a lot of copy-and-paste, but that's not always bad.
Good Day,
I am querying my database using Linq and I have run into a problem, the query searched a column for a search phrase and based on if the column has the phrase, it then returns the results, The query is below,
Dim pdb = New ProductDataContext()
Dim query =
From a In pdb.tblUSSeries
Join b In pdb.tblSizes_ On a.Series Equals b.Series
Where
a.Series.ToString().Equals(searchString) Or
b.Description.Contains(searchString) Or Not b.Description.Contains(Nothing)
Order By b.Series, b.OrderCode Ascending
Select New CustomSearch With
{
.Series = a.Series,
.SeriesDescription= a.Description,
.Coolant = a.Coolant,
.Material = a.Material,
.Standard = a.Standard,
.Surface = a.Surface,
.Type = a.Type,
.PointAngle = a.PointAngle,
.DiaRange = a.DiaRange,
.Shank = b.Shank,
.Flutes = b.Flutes,
.EDPNum = b.EDPNum,
.SizesDescription = b.Description,
.OrderCode = b.OrderCode
}
Return query
I think the problem is that, in the table certain rows are NULL, so when it is checking the column for the phrase and it encounters a row that is null it, breaks and returns this error,
The cast to value type 'System.Int32' failed because the materialized value is null. Either the result type's generic parameter or the query must use a nullable type.
I have ran this query against another column that has all the rows populated with data and it returns the results ok.
So my question is how can I write it in VB to query the db with the supplied searchstring and return the results, when some of the rows in the columns have null values.
Any help would be great.
The exception occurs when you make the projection (i.e. select new CustomSearch)
And yes your trying to assign Null to some int property
(Not sure which one of your properties that is)
one of 2 choices :
1) Use nullalbe types for your properties (or just that one property).
2) project with an inline If ( ?? in C#) , I don't know VB so don't catch me on the syntax.
Taking Series just as an example i don't know if it's an int or if that's the problematic property
Select New CustomSearch With
{
.Series = If(a.Series Is Nothing,0, CInt(a.Series))
}
In C#
Select new CustomSearch
{
Series = a.Series ?? 0;
}
I am new to sharepoint, I have a custom field type derived from SpFieldChoice , my field allows users to select multiple values, I have a requirement of replacing some old custom columns with the new column and copy the data in old column to the new column. the old column also allows the users to select multiple values by ticking checkboxes, I have the following code to copy the data to new field.
foreach (SPListItem item in list.Items)
{
if (item[oldField.Title] == null)
{
item[newFld.Title] = string.Empty;
item.Update();
}
else
{
string[] itemvalues = item[oldField.Title].ToString().Split(new string[] {";#"}, StringSplitOptions.None);
StringBuilder multiLookupValues = new StringBuilder();
multiLookupValues.Append(";#");
for (int cnt = 0; cnt < (itemvalues.Length) / 2; cnt++)
{
multiLookupValues.Append (itemvalues[(cnt * 2) + 1].ToString() + ";#");
}
item[newFld.Title] = multiLookupValues.ToString();
item.SystemUpdate(false) ;
}
}
This code works fine until the length of resulting stringbuilder is less than 255 charachters , but when this length is greater then 255 I get the following Exception.
Invalid choice Value. A choice field contains invalid data.Please check the value and try again.
Is there any other way of copying data to SpFiledChoice, How can I resolve this problem? please help me.
Do the update multiple times so that the string doesn't exceed - i.e. value +=. However, if the problem is that the value can't be longer that 255, you have to consider how you are doing the choices. If it is exceeding the length and updating the value multiple times doesn't work (and a Site Column will have the same limitations), you can do the next best thing:
1) Create a new list that will hold the choices
2) Change the destination field to be a lookup
3) Update accordingly for each item (picking up the ID from the lookup field)
There's no limit to this.
David Sterling
david_sterling#sterling-consulting.com
www.sterling-consulting.com