I am not sure how to convert this simple foreach to linq.
It seems pretty easy, but I keep getting compile errors?
var createAccount = from TransactionDetail td in transactionDetails
Where
td.ResponseType == ResponseType.SUCCESS AND
td.RequestType == RequestType.CREATE_ACCOUNT
SELECT true;
/* trying to convert this */
bool createAccount = true;
foreach(TransactionDetail td in transactionDetails )
{
if (td.RequestType == RequestType.CREATE_ACCOUNT)
{
if (td.ResponseType == ResponseType.SUCCESS)
{
createAccount = false;
}
}
}
If all you want is a boolean result, you don't need where or select. Use the Any method:
bool createAccount = !transactionDetails.Any(
td => td.RequestType == ... && td.ResponseType == ...);
Related
I have seen in one of the issues "Filter on Tree or Nested Data #1562" Oli has mentioned that
Hey #fr0z3nfyr
Filtering is supported on tree child nodes since version 4,2
Cheers
Oli :)
I am unable to find any example or the code to search nested data.
My code works perfectly fine for flat tables, but with nested tables it only works for the root node.
//data - the data for the row being filtered
//filterParams - params object passed to the filter
var match = false;
for (var key in data) {
if (data[key] != null) {
if ((data[key]).indexOf(filterParams.value) != -1) {
match = true;
}
}
}
return match;
}
function updateFilter(){
if ($("#filter-field").val() == "All Columns") {
table.setFilter(matchAny,{ value: $("#filter-value").val()});
} else {
table.setFilter($("#filter-field").val(), "like", $("#filter-value").val());
}
//var filter = $("#filter-field").val() == "All Columns" ? matchAny : $("#filter-field").val() ;
}```
Oli could you please point me to an example where Nested data filtering is supported
I was able to solve this, but by re-setting table data with filtered value and also the tree structure is not maintained in the filtered list. I can maintain the tree structure with some changes in code, but this flat looks more like what I needed once filtering is done.
// This method iterates through the dataRows and its tree children and call a recursive function which creates the filtered table data.
function updateFilter() {
var filtertableData = [];
table.getRows().filter(function (row) {
var rootData = row.getData();
rootData._children = [];
matchData(rootData, filtertableData);
var childRows = row.getTreeChildren();
searchForChildRows(rootData,childRows,filtertableData);
while (childRows.length != 0) {
for (var i = 0; i < childRows.length; i++) {
var childrow = childRows[i];
var childData = childrow.getData();
childData._children = [];
childRows = childrow.getTreeChildren();
searchForChildRows(childData,childRows,filtertableData);
}
}
});
table.setData(filtertableData);
}
function matchData(rootData, filtertableData, childdata) {
if (typeof childdata === "undefined") {
for (var key in rootData) {
console.log(key);
console.log(allVisibleCBSCols);
if (rootData[key] != null && typeof rootData[key] == 'string' && allVisibleCBSCols.includes(key)) {
if ((rootData[key]).indexOf($("#filter-value-Project").val()) != -1) {
filtertableData.push(rootData);
break;
}
}
}
} else {
for (var key in childdata) {
if (childdata[key] != null && typeof childdata[key] == 'string' && allVisibleCBSCols.includes(key)) {
if ((childdata[key]).indexOf($("#filter-value-Project").val()) != -1) {
//rootData._children.push(childdata);
filtertableData.push(childdata);
break;
}
}
}
}
}
function searchForChildRows(rootData,childRows,filtertableData) {
for (var i = 0; i < childRows.length; i++) {
var childrow = childRows[i];
var childData = childrow.getData();
childData._children = [];
matchData(rootData,filtertableData,childData);
}
}
Have read other responses to similar issuebut I can not use PredicateBuilder, or copy its source. I'm trying what I've read here:
<https://blogs.msdn.microsoft.com/meek/2008/05/02/linq-to-entities-combining-predicates/
but as I'm newb, am having trouble with translating what I'm reading to what I'm applying. I have created a L2E query, and trying to append a series of OR clauses onto the WHERE:
So as simplified snippet (this one will be AND'd with the previously already defined WHERE clause):
if (firstParm == "realtor")
query = query.Where(x=> x.A == "realtor");
Now trying to OR:
if (secondParm == "clown")
// how to add this one as an OR to the above query:
query = query.OR(x=> x.fool == "clown");
I understand this can be done also with Union, but not clear on the syntax:
query = query.Union(x=> x.fool == "clown"); // ??
I've also referenced:
Combining two expressions (Expression<Func<T, bool>>)
Unable to create a compound Expression<Func<string, bool>> from a set of expressions
but again, I am new to LINQ and especially Expression Trees, so need more fillin.
There are two ways to generate expressions.
Use the compiler to do it.
Expression<Func<Person, bool>> = p => p.LastName.Contains("A");
Limitations: The only expressions that can be generated this way are instances of LambdaExpression. Also, it is rather complicated to extract parts of the expression and combine with other parts.
Use the static methods at System.Linq.Expressions.Expression.
In order to generate dynamic expressions, you can either choose between different compiler-generated expressions:
// using Record and Records as a placeholder for the actual record type and DbSet property
Expression<Func<Record,bool>> expr;
if (firstParam == "realtor") {
if (secondParam == "clown") {
expr = x => x.A == "realtor" || x.fool == "clown";
} else {
expr = x => x.A == "realtor";
}
} else {
if (secondParam == "clown") {
expr = x => x.fool="clown";
} else {
expr = x => false;
}
}
var ctx = new MyDbContext();
var qry = ctx.Records.Where(expr).Select(x => new {x.A, x.fool});
Or, you can dynamically create the expression using the static methods:
(Add using System.Linq.Expressions; and using static System.Linq.Expressions.Expression; to the top of the file.)
Expression expr;
var parameter = Parameter(typeof(Record));
if (firstParam == "realtor") {
expr = Equals(
MakeMemberAccess(parameter, typeof(Record).GetProperty("A")),
Constant("realtor")
);
}
if (secondParam == "clown") {
var exprClown = Equals(
MakeMemberAccess(parameter, typeof(Record).GetProperty("fool")),
Constant("clown")
);
if (expr == null) {
expr = exprClown;
} else {
expr = Or(expr, exprClown);
}
}
var lambda = Lambda<Func<Record,bool>>(expr, new [] {parameter});
var ctx = new MyDbContext();
var qry = ctx.Records.Where(lambda).Select(x => new {x.A, x.fool});
Given a query with a type unknown at compile time, so any variable referring to it must be IQueryable only, and not IQueryable<T>:
IQueryable qry = ctx.GetQuery(); //dynamically built query here
var parameter = Parameter(qry.ElementType);
if (firstParam == "realtor") {
expr = Equals(
MakeMemberAccess(parameter, qry.ElementType.GetProperty("A")),
Constant("realtor")
);
}
if (secondParam == "clown") {
var exprClown = Equals(
MakeMemberAccess(parameter, qry.ElementType.GetProperty("fool")),
Constant("clown")
);
if (expr == null) {
expr = exprClown;
} else {
expr = Or(expr, exprClown);
}
}
var lambda = Lambda(expr, new [] {parameter});
//Since we don't have access to the TSource type to be used by the Where method, we have
//to invoke Where using reflection.
//There are two overloads of Queryable.Where; we need the one where the generic argument
//is Expression<Func<TSource,bool>>, not Expression<Func<TSource,int,bool>>
var miWhere = typeof(Queryable).GetMethods().Single(mi => {
mi.Name == "Where" &&
mi.GetParameters()[1].ParameterType.GetGenericArguments()[0].GetGenericArguments().Length == 2
});
qry = miWhere.Invoke(null, new [] {qry, lambda});
For Or you can try
if (secondParm == "clown")
{
query = query.Where(x=> x.fool == "clown" || x.fool==x.fool);
}
OR
if (secondParm == "clown")
{
query = query.Where(x=> x.fool == "clown" || true );
}
I'm trying to write following LINQ query using ServiceStack Ormlite.
dbConn.Select<Product>(p => p.IsActive.HasValue && p.IsActive.Value)
Here, Product is my item class and "IsActive" is Nullable Bool property in that class. When this line executes it always throws "InvalidOperationException" with the message
variable 'p' of type '' referenced from scope '', but it is not defined
I tried different variants as following but still same exception result
dbConn.Select<Product>(p => p.IsActive.HasValue == true && p.IsActive.Value == true)
dbConn.Select<Product>(p => p.IsActive != null && p.IsActive.Value == true)
But if I just write
dbConn.Select<Product>(p => p.IsActive.HasValue)
then it works.
I'm puzzled what is the problem? Is this servicestack ormlite issue?
My answer can handle Nullable value like "value" and "HasValue" with servicestack ormlite. And But also with datetime nullable ,like 'createdate.value.Year'.
you must change two place.
modify VisitMemberAccess method:
protected virtual object VisitMemberAccess(MemberExpression m)
{
if (m.Expression != null)
{
if (m.Member.DeclaringType.IsNullableType())
{
if (m.Member.Name == nameof(Nullable<bool>.Value))
return Visit(m.Expression);
if (m.Member.Name == nameof(Nullable<bool>.HasValue))
{
var doesNotEqualNull = Expression.NotEqual(m.Expression, Expression.Constant(null));
return Visit(doesNotEqualNull); // Nullable<T>.HasValue is equivalent to "!= null"
}
throw new ArgumentException(string.Format("Expression '{0}' accesses unsupported property '{1}' of Nullable<T>", m, m.Member));
}
if (m.Member.DeclaringType == typeof(DateTime))
{
var ExpressionInfo = m.Expression as MemberExpression;
if (ExpressionInfo.Member.DeclaringType.IsNullableType())
{
if (ExpressionInfo.Member.Name == nameof(Nullable<bool>.Value))
{
var modelType = (ExpressionInfo.Expression as MemberExpression).Expression.Type;
var tableDef = modelType.GetModelDefinition();
var columnName = (ExpressionInfo.Expression as MemberExpression).Member.Name;
var QuotedColumnName = GetQuotedColumnName(tableDef, columnName);
if (m.Member.Name == "Year")
{
return new PartialSqlString(string.Format("DATEPART(yyyy,{0})", QuotedColumnName));
}
if (m.Member.Name == "Month")
return new PartialSqlString(string.Format("DATEPART(mm,{0})", QuotedColumnName));
}
if (ExpressionInfo.Member.Name == nameof(Nullable<bool>.HasValue))
{
var doesNotEqualNull = Expression.NotEqual(ExpressionInfo.Expression, Expression.Constant(null));
return Visit(doesNotEqualNull); // Nullable<T>.HasValue is equivalent to "!= null"
}
}
else
{
var modelType = ExpressionInfo.Expression.Type;
var tableDef = modelType.GetModelDefinition();
var columnName = ExpressionInfo.Member.Name;
var QuotedColumnName = GetQuotedColumnName(tableDef, columnName);
if (m.Member.Name == "Year")
return new PartialSqlString(string.Format("DATEPART(yyyy,{0})", QuotedColumnName));
if (m.Member.Name == "Month")
return new PartialSqlString(string.Format("DATEPART(mm,{0})", QuotedColumnName));
}
}
if (m.Expression.NodeType == ExpressionType.Parameter || m.Expression.NodeType == ExpressionType.Convert)
{
var propertyInfo = (PropertyInfo)m.Member;
var modelType = m.Expression.Type;
if (m.Expression.NodeType == ExpressionType.Convert)
{
var unaryExpr = m.Expression as UnaryExpression;
if (unaryExpr != null)
{
modelType = unaryExpr.Operand.Type;
}
}
var tableDef = modelType.GetModelDefinition();
if (propertyInfo.PropertyType.IsEnum)
return new EnumMemberAccess(
GetQuotedColumnName(tableDef, m.Member.Name), propertyInfo.PropertyType);
return new PartialSqlString(GetQuotedColumnName(tableDef, m.Member.Name));
}
}
var member = Expression.Convert(m, typeof(object));
var lambda = Expression.Lambda<Func<object>>(member);
var getter = lambda.Compile();
return getter();
}
modify VisitLambda method :
protected virtual object VisitLambda(LambdaExpression lambda)
{
if (lambda.Body.NodeType == ExpressionType.MemberAccess && sep == " ")
{
MemberExpression m = lambda.Body as MemberExpression;
if (m.Expression != null)
{
string r = VisitMemberAccess(m).ToString();
if (m.Member.DeclaringType.IsNullableType())
return r;
return string.Format("{0}={1}", r, GetQuotedTrueValue());
}
}
return Visit(lambda.Body);
}
This is nature of the Linq. In order to achieve what you need, you will need to use two where closes:
dbConn.Where<Product>(p => p.IsActive.HasValue).Where(p=>p.Value==true);
Is there anyway around this error? I'd like to reuse the same lamba expression in other queries instead of having duplication. Can LinqKit or other linq expression do this?
Error
LINQ to Entities does not recognize the method 'Boolean GetEvent(Tournaments.Data.Entities.Event, System.String)' method, and this method cannot be translated into a store expression.
Code
public MobileEventDetailModel GetDetails(string applicationId)
{
var #event = (from e in _eventsRepository.DataContext.Events.Include(q => q.Assets.Select(a => a.Asset))
where GetEvent(e, applicationId)
select new
{
e.Id,
e.EventParent.Name,
LogoId = (from a in e.Assets
where a.Type == EventAssetType.Logo
select a.AssetId).FirstOrDefault()
}).FirstOrDefault();
return new MobileEventDetailModel
{
Id = #event.Id,
Name = #event.Name,
Logo = string.Format("{0}{1}{2}", Config.BaseUrl, Config.ImagesPath, #event.LogoId)
};
}
public bool GetEvent(Event #event, string applicationId)
{
return #event.Active && #event.Visible && #event.MobileEventApplications.Any(m =>
m.MobileApplication.ApplicationId == applicationId &&
(!m.MobileApplication.ActivationLength.HasValue || EntityFunctions.AddDays(DateTime.Now, 1) < EntityFunctions.AddMonths(m.MobileApplication.DateActivated, m.MobileApplication.ActivationLength.Value)));
}
You need to use an Expression:
public MobileEventDetailModel GetDetails(string applicationId)
{
var event = _eventsRepository.DataContext.Events.Include(q => q.Assets.Select(a => a.Asset))
.Where(GetEvent(applicationId))
.Select(a => new
{
a.Id,
a.EventParent.Name,
LogoId = (from b in a.Assets
where b.Type == EventAssetType.Logo
select b.AssetId).FirstOrDefault()
}).FirstOrDefault();
return new MobileEventDetailModel
{
Id = event.Id,
Name = event.Name,
Logo = string.Format("{0}{1}{2}", Config.BaseUrl, Config.ImagesPath, event.LogoId)
};
}
public Expression<Func<Event, bool>> GetEvent(int applicationId)
{
return = a => a.Active
&& a.Visible
&& a.MobileEventApplications
.Any(m => m.MobileApplication.ApplicationId == applicationId
&& (!m.MobileApplication.ActivationLength.HasValue
|| EntityFunctions.AddDays(DateTime.Now, 1)
< EntityFunctions
.AddMonths(m.MobileApplication.DateActivated, m.MobileApplication.ActivationLength.Value)
)
);
}
Update: Sorry it was late the other night, the changed version is hopefully more what you were looking for.
Im trying to write a method which will allow me to search different DataTables, over different columns.
So far i have the following:
string selectedValue;
string searchColumn;
string targetColumn;
var results = (from a in dt.AsEnumerable()
where a.Field<string>(searchColumn) == selectedValue
select new
{
targetColumn = a.Field<string>(targetColumn)
}).Distinct();
Which kind of gets the job done, but I'm left with the column name as targetColumn rather than the actual column name I want.
Is there any way to resolve this?
Thanks in advance
CM
I make a LINQ to Datatables
public List<DataRow> Where(this DataTable dt, Func<DataRow, bool> pred)
{
List<DataRow> res = new List<DataRow>();
try {
if (dt != null && dt.Rows.Count > 0) {
for (i = 0; i <= dt.Rows.Count - 1; i++) {
if (pred(dt(i))) {
res.Add(dt(i));
}
}
}
} catch (Exception ex) {
PromptMsg(ex);
}
return res;
}
Usage :
var RowsList = dt.Where(f => f("SomeField").toString() == "SomeValue" ||
f("OtherField") > 5);