I have read this (http://www.albahari.com/nutshell/predicatebuilder.aspx)
Here is my code :
var predicateOuter = PredicateBuilder.True<T_Users>();
predicateOuter.And(d => d.code== 357);
var count=tService.GetCount(predicateOuter.Expand());
my service in code first:
public int GetCountSearch(Expression<Func<T, bool>> exp)
{
return _entities.Count(exp);
}
all record in T_Users: 6548
all record where code==357 : 26
But it always returns all records. but why ?
You need to use the results of Add:
// Assign result here to predicateOuter -
predicateOuter = predicateOuter.And(d => d.code== 357);
// This should now function properly
var count = tService.GetCount(predicateOuter.Expand());
Add doesn't modify the predicate, but rather returns a new one with the additional criteria.
Related
I am trying to write NHibernate queryover to select all records which has been deleted between two dates. I am using IsBetween().And(). But how do i write if i dont want to include both the fromdate and todate?
Here is my query:
public IEnumerable<DeletedRecord> Search(
DateTime deletedFrom,
DateTime deletedTo
)
{
DeletedRecord delAlias = null;
var query = Session.QueryOver(() => delAlias);
query.Where(() => delAlias.DeletedDate.IsBetween(deletedFrom).And(deletedTo));
return query.Future<DeletedRecord>();
}
Can anyone help me how to achieve so that i can bring all records after the deletedFrom date and before the deletedTo date?
Thanks
Just construct your date in 2 steps:
var query = Session.QueryOver(() => delAlias);
if(youNeedFromDate) //first step
query = query.Where(() => delAlias.DeletedDate >= deletedFrom);
if(youNeedToDate) //second step
query = query.Where(() => delAlias.DeletedDate <= deletedTo);
youNeedFromDate and youNeedToDate are bool variables that you can pass to your function or it could be different condition upon your logic.
Such cases happen quite often . defining extension method helps a lot. see below
public static IQueryOver<T, T> WhereIf<T>(this IQueryOver<T, T> query,bool condition, Expression<Func<T, bool>> expression) where T : class
{
if (condition)
{
query = query.And(expression);
}
return query;
}
Using the above you can chain you conditions and only it will only include the where condition if the first arg evaluates to true.
var query= Session.QueryOver<DeletedRecord>()
.WhereIf(filterByFrom,d=>d.DeletedDate>=fromDate)
.WhereIf(filterByTo,d=>d.DeletedDate<=toDate);
It's difficult to explain the case by words, let me give an example:
var myObj = {
'name': 'Umut',
'age' : 34
};
var prop = 'name';
var value = 'Onur';
myObj[name] = value; // This does not work
eval('myObj.' + name) = value; //Bad coding ;)
How can I set a variable property with variable value in a JavaScript object?
myObj[prop] = value;
That should work. You mixed up the name of the variable and its value. But indexing an object with strings to get at its properties works fine in JavaScript.
myObj.name=value
or
myObj['name']=value (Quotes are required)
Both of these are interchangeable.
Edit: I'm guessing you meant myObj[prop] = value, instead of myObj[name] = value. Second syntax works fine: http://jsfiddle.net/waitinforatrain/dNjvb/1/
You can get the property the same way as you set it.
foo = {
bar: "value"
}
You set the value
foo["bar"] = "baz";
To get the value
foo["bar"]
will return "baz".
You could also create something that would be similar to a value object (vo);
SomeModelClassNameVO.js;
function SomeModelClassNameVO(name,id) {
this.name = name;
this.id = id;
}
Than you can just do;
var someModelClassNameVO = new someModelClassNameVO('name',1);
console.log(someModelClassNameVO.name);
simple as this
myObj.name = value;
When you create an object myObj as you have, think of it more like a dictionary. In this case, it has two keys, name, and age.
You can access these dictionaries in two ways:
Like an array (e.g. myObj[name]); or
Like a property (e.g. myObj.name); do note that some properties are reserved, so the first method is preferred.
You should be able to access it as a property without any problems. However, to access it as an array, you'll need to treat the key like a string.
myObj["name"]
Otherwise, javascript will assume that name is a variable, and since you haven't created a variable called name, it won't be able to access the key you're expecting.
You could do the following:
var currentObj = {
name: 'Umut',
age : 34
};
var newValues = {
name: 'Onur',
}
Option 1:
currentObj = Object.assign(currentObj, newValues);
Option 2:
currentObj = {...currentObj, ...newValues};
Option 3:
Object.keys(newValues).forEach(key => {
currentObj[key] = newValues[key];
});
Is it possible to log variable name (not value) in JavaScript?
var max_value = 4;
console.log(max_value); // should log "max_value" as a string
UPDATE: I need a testing function that should be able to log any variable name (passed as an argument) as a string, not just this one variable.
There is a solution that can help you. I grabbed this function from this stackoverflow answer, which is able to get the name of the function parameters:
var STRIP_COMMENTS = /((\/\/.*$)|(\/\*[\s\S]*?\*\/))/mg;
var ARGUMENT_NAMES = /([^\s,]+)/g;
function getParamNames(func) {
var fnStr = func.toString().replace(STRIP_COMMENTS, '');
var result = fnStr.slice(fnStr.indexOf('(')+1, fnStr.indexOf(')')).match(ARGUMENT_NAMES);
if(result === null)
result = [];
return result;
}
then all you need to do now, is to use the name of your variable as a parameter of an anonymous function and pass all the function as argument of the getParamNames :
variablesNames = getParamNames(function (max_value, min_value) {});
This will return an array like this :
result => ["max_value", "min_value"];
Let's make it practical, first change the name of the getParamNames function to something easy and small like this :
function __ (func) {
// code here ...
}
second thing, instead of returning an array, just return the first element of the array, change this :
return result;
to this :
return result.shift();
now, you can get the name of your variable like this :
__(function( max_value ){});
Suppose i have 2 records in data base
1) 2007-12-10 10:35:31.000
2) 2008-12-10 10:35:31.000
FirstOrDefault() method will give me the first record match in sequence like 2007-12-10 10:35:31.000 but i need the latest one which is 2008-12-10 10:35:31.000
if ((from value in _names where value != null select value.ExpiryDate < now).Any())
{
return _names.FirstOrDefault();
}
You can use:
return _names.LastOrDefault();
However, your if just sends another unnecessary query (and it is a wrong query too). If you don't have any record, LastOrDefault and FirstOrDefault will return null. You can use something like this to improve the code:
var name = _names.LastOrDefault();
if(name != null)
{
return name;
}
// other code here
If you really want to use FirstOrDefault, you should order descending, like:
var name = _names.Where(n => n.ExpiryDate < now).OrderByDescending(n => n.ExpiryDate).FirstOrDefault();
When I query my database with a function passed in the "$where" clause in nodejs, it always return me all documents in the db.
For example, if I do
var stream = timetables.find({$where: function() { return false; }}).stream();
it return me all the documents.
Instead, if I do
var stream = timetables.find({$where: 'function() { return false; }'}).stream();
the function is really executed, and this code doesn't return any document.
The problem is that if I convert in string my function the context's bindinds are removed, and I need them for more complex query. For example:
var n = 1;
var f = function() { return this.number == n; }
var stream = timetables.find({$where: f.toString()}).stream();
// error: n is not defined
Is this a normal behaviour? How can I solve my problem?
Please excuse me for my poor english!
First off, keep in mind that the $where operator should almost never be used for the reasons explained here (credit goes to #WiredPrairie).
Back to your issue, the approach you'd like to take won't work even in the mongodb shell (which explicitly allows naked js functions with the $where operator). The javascript code provided to the $where operator is executed on the mongo server and won't have access to the enclosing environment (the "context bindings").
> db.test.insert({a: 42})
> db.test.find({a: 42})
{ "_id" : ObjectId("5150433c73f604984a7dff91"), "a" : 42 }
> db.test.find({$where: function() { return this.a == 42 }}) // works
{ "_id" : ObjectId("5150433c73f604984a7dff91"), "a" : 42 }
> var local_var = 42
> db.test.find({$where: function() { return this.a == local_var }})
error: {
"$err" : "error on invocation of $where function:\nJS Error: ReferenceError: local_var is not defined nofile_b:1",
"code" : 10071
}
Moreover it looks like that the node.js native mongo driver behaves differently from the shell in that it doesn't automatically serialize a js function you provide in the query object and instead it likely drops the clause altogether. This will leave you with the equivalent of timetables.find({}) which will return all the documents in the collection.
This one is works for me , Just try to store a query as a string in one variable then concat your variable in query string,
var local_var = 42
var query = "{$where: function() { return this.a == "+local_var+"}}"
db.test.find(query)
Store your query into a varibale and use that variable at your find query. It works..... :D
The context will always be that of the mongo database, since the function is executed there. There is no way to share the context between the two instances. You have to rethink the way you query and come up with a different strategy.
You can use a wrapper to pass basic JSON objects, ie. (pardon coffee-script):
# That's the main wrapper.
wrap = (f, args...) ->
"function() { return (#{f}).apply(this, #{JSON.stringify(args)}) }"
# Example 1
where1 = (flag) ->
#myattr == 'foo' or flag
# Example 2 with different arguments
where2 = (foo, options = {}) ->
if foo == options.bar or #_id % 2 == 0
true
else
false
db.collection('coll1').count $where: wrap(where1, true), (err, count) ->
console.log err, count
db.collection('coll1').count $where: wrap(where2, true, bar: true), (err, count) ->
console.log err, count
Your functions are going to be passed as something like:
function () {
return (function (flag) {
return this.myattr === 'foo' || flag;
}).apply(this, [true])
}
...and example 2:
function () {
return (
function (foo, options) {
if (options == null) {
options = {};
}
if (foo === options.bar || this._id % 2 === 0) {
return true;
} else {
return false;
}
}
).apply(this, [ true, { "bar": true } ])
}
This is how it is supposed to be. The drivers don't translate the client code into the mongo function javascript code.
I'm assuming you are using Mongoose to query your database.
If you take a look at the actual Query object implementation, you'll find that only strings are valid arguments for the where prototype.
When using the where clause, you should use it along with the standard operators such as gt, lt that operates on in the path created by the where function.
Remember that Mongoose querying, as in Mongo, is by example, you may want to reconsider your query specification in a more descriptive fashion.