I am trying to empty the recycleBin. Thus I need to query the existing SObjects of the records. If a match of the records SObject Name has been found, than the query should happen. Else it just shouldn't query anything. The return type is a query.
How should I write the else part without having crashing problems when the SObject does not exists.
I thought of a try catch block where the try part would contain the
if(exists){query;}
and the catch part would just don't do anything, means it would be empty. Does that make sense?
What would you suggest?
Boolean exists = Schema.getGlobalDescribe().containsKey(sObjectName);
try {
if(exists){
return Database.getQueryLocator('SELECT Id FROM ' + sObjectName
+' WHERE isDeleted=true ALL ROWS');
}
}
catch (QueryException ex) {
// do nothing
}
Assuming you have a method which will return the Database.getQueryLocator
public Database.QueryLocator testMethod(String sObjectName )
{
return Database.getQueryLocator('SELECT Id FROM ' + sObjectName
+' WHERE isDeleted=true ALL ROWS');
}
Check if the sObject exists before calling the method.
Boolean exists = Schema.getGlobalDescribe().containsKey(sObjectName);
if(exists)
{
Database.QueryLocator ql = testMethod(String sObjectName);
}
Related
Here's what I tried:
public Collection<User> updateUsers(Collection<User> users) {
Collection<User> usersUpdated = null;
users.stream()
.filter(u -> userRepository.existsById(u.getId()))
.forEach(
u -> {
Optional<User> user = userRepository.findById(u.getId());
userRepository.save(user);
usersUpdated.add(userRepository.findById(u.getId()));
logger.debug("Update single " + User.class.getName() + ": " + u);
}
);
return usersUpdated;
}
The issue is on userRepository.save(user) where I'm getting the following:
Inferred type 'S' for type parameter 'S' is not within its bound; should extend 'com.example.model.User'
How should I properly update a collection of this entity?
You're getting the 'Inferred type not within its bound' exception, because you're passing an Optional to the save method, instead of a User object.
And I would suggest that you can save the entire collection with one request to the database, using CrudRepository.saveAll(), like this:
userRepository.saveAll(users);
I want to check the username and password with sqlite table,In my case query always returns false...
This is my Query...
public boolean validateUser(String u_name, String p_word){
Cursor c = getReadableDatabase().rawQuery(
"SELECT FNAME,PASSWORD FROM " + TABLE_NAME + " WHERE "
+ fname + "='" + u_name+"'AND "+ password +"='"+ p_word+"'" , null);
if (c!=null)
{
return true;
}
else{
return false;
}
}
Checking whether or not the Cursor is null is basically useless as a valid Cursor will be returned by rawQuery. That is no data to extract will result in an empty Cursor with no rows, whilst if data has been extracted the Cursor will have 1 or more rows.
You should check whether or not the Cursor is empty by using the Cursor getCount() method which will return 0 if there are no rows or the number of rows. Alternately you could use some of the Cursor's move methods which will return true/false depending upon whether the move can be performed. e.g if (c.moveToFirst) { ... //row(s) exist} else { ... //no rows exists }.
You should also close the Cursor before returning. So perhaps use :-
public boolean validateUser(String u_name, String p_word){
Cursor c = getReadableDatabase().rawQuery(
"SELECT FNAME,PASSWORD FROM " + TABLE_NAME + " WHERE "
+ fname + "='" + u_name+"'AND "+ password +"='"+ p_word+"'" , null);
int count = c.getCount(); // get the number of rows
c.close(); // Close the Cursor
return count > 0; // return result (no data found = false, else true)
Many would recommend not using rawQuery but rather the convenience Cursor query method. This could be :-
public boolean validateUser(String u_name, String p_word) {
String[] columns = new String[]{
FNAME,
PASSWORD
};
String whereclause = FNAME + "=? AND " + PASSWORD + "=?";
String[] whereargs = new String[]{
u_name,
p_word
};
Cursor c = this.getWritableDatabase().query(
TABLE_NAME,
columns,
whereclause,
whereargs,
null,null,null
);
int count = c.getCount();
c.close();
return count > 0;
}
Note the above code is in-principle code and hasn't been tested so it may contain typing errors.
The above code assumes that the method is within the Database Helper class (i.e. a subclass of SQLiteOpenHelper).
The assumption has been made that FNAME and PASSWORD are the correct String variables to be used for the column names as opposed to fname and password
Assumptions have been made due to the limited code made available.
I'm using WCF RIA in a Lightswitch project to create some query results. This query brings back all results regardless. I cannot make it filter the records based on the parameter passed (string Town).
public IQueryable<Enquiries> TestQuery(string Town)
{
List<Enquiries> riaenqs = new List<Enquiries>();
var enqs = this.Context.ClientEnquiries
.Include("Client")
.Include("Client.Town")
.OrderBy(enq => enq.Id);
if (Town != null)
{
enqs.Where(enq => enq.Client.Town.TownName == Town);
}
foreach (ClientEnquiry item in enqs.ToList())
{
Enquiries enq = new Enquiries();
enq.Id = item.Id;
enq.ClientName = item.Client.FirstName + " " + item.Client.Surname;
enq.Town = item.Client.Town != null ? item.Client.Town.TownName : null;
riaenqs.Add(enq);
}
return riaenqs.AsQueryable();
}
During debugging I can see that the Town is correctly populated and I can see that the query is built accordingly if Town is not null. However, when I hit the foreach statement where the linq to ef query is executed I always get all the results. I just cannot figure out where I'm slipping up.
The LINQ methods like the Where do not modify the collection/expression but always returning a new one.
So you need to reassign the result of the Where to your original variable enqs:
if (Town != null)
{
enqs = enqs.Where(enq => enq.Client.Town.TownName == Town);
}
I'm using entity framework 4.
I have a stored procedure that just updates one value in my table, namely the application state ID. So I created a stored procedure that looks like this:
ALTER PROCEDURE [dbo].[UpdateApplicationState]
(
#ApplicationID INT,
#ApplicationStateID INT
)
AS
BEGIN
UPDATE
[Application]
SET
ApplicationStateID = #ApplicationStateID
WHERE
ApplicationID = #ApplicationID;
END
I created a function import called UpdateApplicationState. I had initially set its return type to null, but then it wasn't created in the context. So I changed its return type to int. Now it was created in the context. Is it wise to return something from my stored procedure?
Here is my method in my ApplicationRepository class:
public void UpdateApplicationState(int applicationID, int applicationStateID)
{
var result = context.UpdateApplicationState(applicationID, applicationStateID);
}
Here is my calling code to this method in my view:
applicationRepository.UpdateApplicationState(id, newApplicationStateID);
When I run it then I get the following error:
The data reader returned by the store
data provider does not have enough
columns for the query requested.
Any idea/advise on what I can do to get this to work?
Thanks
To get POCO to work with function imports that return null, you can customize the .Context.tt file like this.
Find the "Function Imports" named region (the section that starts with region.Begin("Function Imports"); and ends with region.End();) in the .Context.tt file and replace that whole section with the following:
region.Begin("Function Imports");
foreach (EdmFunction edmFunction in container.FunctionImports)
{
var parameters = FunctionImportParameter.Create(edmFunction.Parameters, code, ef);
string paramList = String.Join(", ", parameters.Select(p => p.FunctionParameterType + " " + p.FunctionParameterName).ToArray());
var isReturnTypeVoid = edmFunction.ReturnParameter == null;
string returnTypeElement = String.Empty;
if (!isReturnTypeVoid)
returnTypeElement = code.Escape(ef.GetElementType(edmFunction.ReturnParameter.TypeUsage));
#>
<# if (isReturnTypeVoid) { #>
<#=Accessibility.ForMethod(edmFunction)#> void <#=code.Escape(edmFunction)#>(<#=paramList#>)
<# } else { #>
<#=Accessibility.ForMethod(edmFunction)#> ObjectResult<<#=returnTypeElement#>> <#=code.Escape(edmFunction)#>(<#=paramList#>)
<# } #>
{
<#
foreach (var parameter in parameters)
{
if (!parameter.NeedsLocalVariable)
{
continue;
}
#>
ObjectParameter <#=parameter.LocalVariableName#>;
if (<#=parameter.IsNullableOfT ? parameter.FunctionParameterName + ".HasValue" : parameter.FunctionParameterName + " != null"#>)
{
<#=parameter.LocalVariableName#> = new ObjectParameter("<#=parameter.EsqlParameterName#>", <#=parameter.FunctionParameterName#>);
}
else
{
<#=parameter.LocalVariableName#> = new ObjectParameter("<#=parameter.EsqlParameterName#>", typeof(<#=parameter.RawClrTypeName#>));
}
<#
}
#>
<# if (isReturnTypeVoid) { #>
base.ExecuteFunction("<#=edmFunction.Name#>"<#=code.StringBefore(", ", String.Join(", ", parameters.Select(p => p.ExecuteParameterName).ToArray()))#>);
<# } else { #>
return base.ExecuteFunction<<#=returnTypeElement#>>("<#=edmFunction.Name#>"<#=code.StringBefore(", ", String.Join(", ", parameters.Select(p => p.ExecuteParameterName).ToArray()))#>);
<# } #>
}
<#
}
region.End();
What I'm doing here is instead of ignoring all function imports that return null, I'm creating a method that returns null. I hope this is helpful.
It is because you do not actually returning anything from your stored procedure. Add a line like below to your SP (SELECT ##ROWCOUNT), and it will be executing properly.
BEGIN
...
SELECT ##ROWCOUNT
END
While this solution will address your issue and actually returns the number of effected rows by your SP, I am not clear on why this is an issue for you:
I had initially set its return type to null, but then it wasn't created in the context.
When doing a Function Import, you can select "None" as return type and it will generate a new method on your ObjectContext with a return type of int. This method basically executes a stored procedure that is defined in the data source; discards any results returned from the function; and returns the number of rows affected by the execution.
EDIT: Why a Function without return value is ignored in a POCO Scenario:
Drilling into ObjectContext T4 template file coming with ADO.NET C# POCO Entity Generator reveals why you cannot see your Function in your ObjectContext class: Simply it's ignored! They escape to the next iteration in the foreach loop that generates the functions.
The workaround for this is to change the T4 template to actually generate a method for Functions without return type or just returning something based on the first solution.
region.Begin("Function Imports");
foreach (EdmFunction edmFunction in container.FunctionImports)
{
var parameters = FunctionImportParameter.Create(edmFunction.Parameters, code, ef);
string paramList = String.Join(", ", parameters.Select(p => p.FunctionParameterType + " " + p.FunctionParameterName).ToArray());
// Here is why a Function without return value is ignored:
if (edmFunction.ReturnParameter == null)
{
continue;
}
string returnTypeElement = code.Escape(ef.GetElementType(edmFunction.ReturnParameter.TypeUsage));
...
I'm attempting to parse SQL using the TSql100Parser provided by microsoft. Right now I'm having a little trouble using it the way it seems to be intended to be used. Also, the lack of documentation doesn't help. (example: http://msdn.microsoft.com/en-us/library/microsoft.data.schema.scriptdom.sql.tsql100parser.aspx )
When I run a simple SELECT statement through the parser it returns a collection of TSqlStatements which contains a SELECT statement.
Trouble is, the TSqlSelect statement doesn't contain attributes such as a WHERE clause, even though the clause is implemented as a class. http://msdn.microsoft.com/en-us/library/microsoft.data.schema.scriptdom.sql.whereclause.aspx
The parser does recognise the WHERE clause as such, looking at the token stream.
So, my question is, am I using the parser correctly? Right now the token stream seems to be the most useful feature of the parser...
My Test project:
public static void Main(string[] args)
{
var parser = new TSql100Parser(false);
IList<ParseError> Errors;
IScriptFragment result = parser.Parse(
new StringReader("Select col from T1 where 1 = 1 group by 1;" +
"select col2 from T2;" +
"select col1 from tbl1 where id in (select id from tbl);"),
out Errors);
var Script = result as TSqlScript;
foreach (var ts in Script.Batches)
{
Console.WriteLine("new batch");
foreach (var st in ts.Statements)
{
IterateStatement(st);
}
}
}
static void IterateStatement(TSqlStatement statement)
{
Console.WriteLine("New Statement");
if (statement is SelectStatement)
{
PrintStatement(sstmnt);
}
}
Yes, you are using the parser correctly.
As Damien_The_Unbeliever points out, within the SelectStatement there is a QueryExpression property which will be a QuerySpecification object for your third select statement (with the WHERE clause).
This represents the 'real' SELECT bit of the query (whereas the outer SelectStatement object you are looking at has just got the 'WITH' clause (for CTEs), 'FOR' clause (for XML), 'ORDER BY' and other bits)
The QuerySpecification object is the object with the FromClauses, WhereClause, GroupByClause etc.
So you can get to your WHERE Clause by using:
((QuerySpecification)((SelectStatement)statement).QueryExpression).WhereClause
which has a SearchCondition property etc. etc.
Quick glance around would indicate that it contains a QueryExpression, which could be a QuerySpecification, which does have the Where clause attached to it.
if someone lands here and wants to know how to get the whole elements of a select statement the following code explain that:
QuerySpecification spec = (QuerySpecification)(((SelectStatement)st).QueryExpression);
StringBuilder sb = new StringBuilder();
sb.AppendLine("Select Elements");
foreach (var elm in spec.SelectElements)
sb.Append(((Identifier)((Column)((SelectColumn)elm).Expression).Identifiers[0]).Value);
sb.AppendLine();
sb.AppendLine("From Elements");
foreach (var elm in spec.FromClauses)
sb.Append(((SchemaObjectTableSource)elm).SchemaObject.BaseIdentifier.Value);
sb.AppendLine();
sb.AppendLine("Where Elements");
BinaryExpression binaryexp = (BinaryExpression)spec.WhereClause.SearchCondition;
sb.Append("operator is " + binaryexp.BinaryExpressionType);
if (binaryexp.FirstExpression is Column)
sb.Append(" First exp is " + ((Identifier)((Column)binaryexp.FirstExpression).Identifiers[0]).Value);
if (binaryexp.SecondExpression is Literal)
sb.Append(" Second exp is " + ((Literal)binaryexp.SecondExpression).Value);
I had to split a SELECT statement into pieces. My goal was to COUNT how many record a query will return. My first solution was to build a sub query such as
SELECT COUNT(*) FROM (select id, name from T where cat='A' order by id) as QUERY
The problem was that in this case the order clause raises the error "The ORDER BY clause is not valid in views, inline functions, derived tables, sub-queries, and common table expressions, unless TOP or FOR XML is also specified"
So I built a parser that split a SELECT statment into fragments using the TSql100Parser class.
using Microsoft.Data.Schema.ScriptDom.Sql;
using Microsoft.Data.Schema.ScriptDom;
using System.IO;
...
public class SelectParser
{
public string Parse(string sqlSelect, out string fields, out string from, out string groupby, out string where, out string having, out string orderby)
{
TSql100Parser parser = new TSql100Parser(false);
TextReader rd = new StringReader(sqlSelect);
IList<ParseError> errors;
var fragments = parser.Parse(rd, out errors);
fields = string.Empty;
from = string.Empty;
groupby = string.Empty;
where = string.Empty;
orderby = string.Empty;
having = string.Empty;
if (errors.Count > 0)
{
var retMessage = string.Empty;
foreach (var error in errors)
{
retMessage += error.Identifier + " - " + error.Message + " - position: " + error.Offset + "; ";
}
return retMessage;
}
try
{
// Extract the query assuming it is a SelectStatement
var query = ((fragments as TSqlScript).Batches[0].Statements[0] as SelectStatement).QueryExpression;
// Constructs the From clause with the optional joins
from = (query as QuerySpecification).FromClauses[0].GetString();
// Extract the where clause
where = (query as QuerySpecification).WhereClause.GetString();
// Get the field list
var fieldList = new List<string>();
foreach (var f in (query as QuerySpecification).SelectElements)
fieldList.Add((f as SelectColumn).GetString());
fields = string.Join(", ", fieldList.ToArray());
// Get The group by clause
groupby = (query as QuerySpecification).GroupByClause.GetString();
// Get the having clause of the query
having = (query as QuerySpecification).HavingClause.GetString();
// Get the order by clause
orderby = ((fragments as TSqlScript).Batches[0].Statements[0] as SelectStatement).OrderByClause.GetString();
}
catch (Exception ex)
{
return ex.ToString();
}
return string.Empty;
}
}
public static class Extension
{
/// <summary>
/// Get a string representing the SQL source fragment
/// </summary>
/// <param name="statement">The SQL Statement to get the string from, can be any derived class</param>
/// <returns>The SQL that represents the object</returns>
public static string GetString(this TSqlFragment statement)
{
string s = string.Empty;
if (statement == null) return string.Empty;
for (int i = statement.FirstTokenIndex; i <= statement.LastTokenIndex; i++)
{
s += statement.ScriptTokenStream[i].Text;
}
return s;
}
}
And to use this class simply:
string fields, from, groupby, where, having, orderby;
SelectParser selectParser = new SelectParser();
var retMessage = selectParser.Parse("SELECT * FROM T where cat='A' Order by Id desc",
out fields, out from, out groupby, out where, out having, out orderby);