I have some problems wo use a key-value-map into Velocity.
Someone has an example of this functionality?
$myMap ={}
$myMap.put("mykey1", "myvalue")
$myMap.delete("mykey1")
$myMap.getValue("mykey1")
As Nathan said, you should use:
#set ($myMap = {})
to create a new map and assign it to a variable.
Now, why is the put call printed.
Anything that is not inside a directive, like #set(not printed) or #if(not printed) or #foreach(again not printed), is printed, including free text, variables, and method calls.
Velocity can't distinguish between the different semantics of $myMap.get('mykey') and $myMap.put('key', 'value') (reader vs. writer), so the result of the put call is printed, just like any other method.
Whenever something can't be properly evaluated, because a variable is not defined or somewhere along the line a method returns null, the code that failed to be evaluated is dumped literally into the output.
As the documentation of the put method states, the function returns the previous value stored for that key, or null if no value was set at all.
Summing it all up, it's normal to get that line printed.
To try this theory out, you can do this:
#set ($myMap = {})
$myMap.put('key', 'first value')
$myMap.put('key', 'second value')
$myMap.get('key')
This will be printed:
$myMap.put('key', 'first value')
first value
second value
There are two things you can do so that the line isn't printed:
Store the outcome of the function in a temporary variable: #set ($discard = $myMap.put('key', 'value')
Use the silent method call: $!myMap.put('key', 'value')
I'd recommend the first one, since the second one will still print something when you're replacing an existing value.
Did you try doing:
#set( $myMap = {} )
Also, make sure you are using a modern version of Velocity. Ancient ones did not have map syntax in VTL.
Just add ! to not print put:
$!myMap.put('key', 'second value')
Related
In Dart/Flutter, suppose you have an instance a of Class Y.
Class Y has a property, property1.
You want to print that property using string interpolation like so:
print('the thing I want to see in the console is: $a.property1');
But you can't even finish typing that in without getting an error.
The only way I can get it to work is by doing this:
var temp = a.property1;
print ('the thing I want to see in the console is: $temp');
I haven't found the answer online... and me thinks there must be a way to just do it directly without having to create a variable first.
You need to enclose the property in curly braces:
print('the thing I want to see in the console is: ${a.property}');
That will then print the value of a.property.
It seems you can also do this, but it doesn't seem to be documented anywhere:
print('..... $a.$property1');
Is there any reason that this syntax shouldn't work in Qlikview load script??
Let v_myNumber = year(today());
Let v_myString = '2017-08';
If left($(v_myString),4) = text($(v_myNumber)) Then
'do something
Else
'do something else
End If;
I've tried both ways where I convert variable string to number and evaluate against the number variable directly and this way. They won't evaluate to equivalence when they should..
Left function is expecting a string as is getting something else as a parameter. As you are currently doing, the function will be called as Left(2017-08, 4) which is unhandle by QlikView.
If you use Left('$(v_myString)',4), it will evaluate as Left('2017-08', 4) as work as expected. Just adding quotes around the variable it should work.
Although QlikView calls them variables, they should really be seen as "stuff to replaced (at sometimes evaluated) at runtime", which is slightly different from a standard "variable" behaviour.
Dollar sign expansion is a big subject, but in short:
if you are setting a variable - no need for $().
if you are using a variable - you can use $(). depends on its context.
if you are using a variable that needs to be evaluated - you have to use $().
for example in a load script: let var1 = 'if(a=1,1,2)' - here later on the script you will probably want to use this variable as $(var1) so it will be evaluated on the fly...
I hope its a little more clear now. variable can be used in many ways at even can take parameters!
for example:
var2 = $1*$2
and then you can use like this: $(var2(2,3)) which will yield 6
For further exploration of this, I would suggest reading this
I have a HashMap in my bean:
HashMap<String, SomeObject> someHashMap;
Then in the velocity template I need to access the HashMap with a value that I have in velocity from other source (in fact I have many keys not only one that's why I need to get the values this way):
$key
How can I access the hashmap with this key? I'm trying:
$someHashMap.get($key)
and
${someHashMap.get($key)}
But those two only write the same thing to the output, meaning that with the first line I literally get:
$someHashMap.get($key)
In the webpage.
Which is the correct way/syntaxis to do this?
Thanks!
Both are correct syntax, and they should work.
Does $key have the right value? Print it.
Does $someHashMap indeed point to the map? Print it. If not, perhaps you forgot to put in the VelocityContext being used.
Is the value stored under that key null? The default behavior of Velocity is to print out the code that was called when the outcome is null. To make it not do that, use the silent notation: $!{someHashMap.get($key)}
I had this exact same problem. In my case I tried to do this:
$map.get($locale)
where $locale is e.g. "fi_FI". I solved it by adding quotes inside the brackets:
$map.get("$locale")
I'm not sure, but I think the rationale goes like this:
$map.get( $locale ) -> $map.get( fi_FI ) -> Velocity gets confused
$map.get("$locale") -> $map.get("fi_FI") -> Velocity retrieves correct value
I tested this query in my database, and it works fine:
select * from variables where value = 'commas-:-)';
I get a result. Now, I stored the value in a variable and use the query class.
$value = 'commas-:-)' <<< this is passed as a parameter
$query = "select * from variables where value = '$value'";
$this->db->query($query);
Now, this query works for every other value except for this one - but what's odd is that if I PRINT out the exact query (print_r of $query) and execute it on the database, it returns the correct result. So I'm left to think that the query class is screwing with my query, which it shouldn't because everything is properly escaped and $value is a string literal.
What is going on?
$sql = "SELECT * FROM variables WHERE value = ?";
$this->db->query($sql, array('commas-:-)'));
More info
$get_data = $this->db->from('variables')
->where('value', $value)
->get();
Hope this will work...!
try to use these things for checking the queries
echo $this->db->last_query();
print_r($this->db->result_array($get_data));
I found the issue - it was the rerouting function that was causing the mishap. More specifically, the segment filtering function within the route folder in the system core.
This is what happened:
I created an anchor with the encoded value (commas:-)) and I configured the route to reroute the uri to a function I had in my controller. Each time I clicked the link, the value gets passed, and (supposedly) rerouted to the function. Which it did, for almost all the values I used. Except this one.
1st assumption: the db query function is escaping the values. But I turned off the escape, as well as checked the query by printing. The value was correct. I then tried other query formats, and still no results. Conclusion: There's nothing wrong with the database query functions.
2nd assumption: the data must be corrupt - although the value is correct (I'm getting commas:-)), it's not returning anything except when I type in the value manually. So I tested this:
I created a seperate value, and set it equals to the one I typed in(the one that works). I then printed the original value(one passed) and the newly created value using VAR_DUMP.
Turns out, the argument value (one that doesn't work) is a string with length 14 whereas my new variable was a string with a length of 10. WTF? Conclusion: Something occured during the rerouting / passing process that changed the variable.
I went back to the config folder, and replace the variable $i in the reroute to the literal string value commas:-). And guess what? It worked perfectly. And just to make sure it wasn't the regex, I wrote my own custom regex and it matched fine, but the value was still being changed. So I decided to get under the hood.
I traced the URI manipulation in the routes class to the _explode_segment() function, which was used to perform the regex and analyse the uri for other variables. It also did this thing ...
_filter_uri($str)
for each part of the uri segment that was matched.
What did it do? It replaces programmable characters like ( and ) with their HTML ENTITY. Now, if you don't know, html entities have long lengths than url encoding. LOL. So what happened was this:
Original segment : commas-%3A-%29 <- very nice!
Filtered segment : commas-%3A-) <- NOOOOOOOOO! (the right paren encoded with ).)
urldecode(")") = string(4)
urldecode("%29") = string(1)
Fail.
or WIN?!
When I´m using MATLAB, sometimes I feel the need to make comments on some variables. I would like to save these comments inside these variables. So when I have to work with many variables in the workspace, and I forget the context of some of these variables I could read the comments I put in every one of them. So I would like to comment variables and keep the comments inside of them.
While I'm of the opinion that the best (and easiest) approach would be to make your variables self-documenting by giving them descriptive names, there is actually a way for you to do what you want using the object-oriented aspects of MATLAB. Specifically, you can create a new class which subclasses a built-in class so that it has an additional property describing the variable.
In fact, there is an example in the documentation that does exactly what you want. It creates a new class ExtendDouble that behaves just like a double except that it has a DataString property attached to it which describes the data in the variable. Using this subclass, you can do things like the following:
N = ExtendDouble(10,'The number of data points')
N =
The number of data points
10
and N could be used in expressions just as any double value would. Using this example subclass as a template, you could create "commented" versions of other built-in numeric classes, with the exception of those you are not allowed to subclass (char, cell, struct, and function_handle).
Of course, it should be noted that instead of using the ExtendDouble class like I did in the above example, I could instead define my variable like so:
nDataPoints = 10;
which makes the variable self-documenting, albeit with a little more typing needed. ;)
How about declaring another variable for your comments?
example:
\>> num = 5;
\>> numc = 'This is a number that contains 5';
\>> whos
...
This is my first post in StackOverflow. Thanks.
A convenient way to solve this is to have a function that does the storing and displaying of comments for you, i.e. something like the function below that will pop open a dialog box if you call it with comments('myVar') to allow you to enter new (or read/update previous) comments to variable (or function, or co-worker) labeled myVar.
Note that the comments will not be available in your next Matlab session. To make this happen, you have to add save/load functionality to comments (i.e. every time you change anything, you write to a file, and any time you start the function and database is empty, you load the file if possible).
function comments(name)
%COMMENTS stores comments for a matlab session
%
% comments(name) adds or updates a comment stored with the label "name"
%
% comments prints all the current comments
%# database is a n-by-2 cell array with {label, comment}
persistent database
%# check input and decide what to do
if nargin < 1 || isempty(name)
printDatabase;
else
updateDatabase;
end
function printDatabase
%# prints the database
if isempty(database)
fprintf('no comments stored yet\n')
else
for i=1:size(database,1)
fprintf('%20s : %s\n',database{i,1},database{i,2});
end
end
end
function updateDatabase
%# updates the database
%# check whether there is already a comment
if size(database,1) > 0 && any(strcmp(name,database(:,1)))
idx = strcmp(name,database(:,1));
comment = database(idx,2);
else
idx = size(database,1)+1;
comment = {''};
end
%# ask for new/updated comment
comment = inputdlg(sprintf('please enter comment for %s',name),'add comment',...
5,comment);
if ~isempty(comment)
database{idx,1} = name;
database(idx,2) = comment;
end
end
end
Always always always keep the Matlab editor open with a script documenting what you do. That is, variable assignments and calculations.
Only exceptions are very short sessions where you want to experiment. Once you have something -- add it to the file (It's also easier to cut and paste when you can see your entire history).
This way you can always start over. Just clear all and rerun the script. You never have random temporaries floating around in your workspace.
Eventually, when you are finished, you will also have something that is close to 'deliverable'.
Have you thought of using structures (or cells, although structures would require extra memory use)?
'>> dataset1.numerical=5;
'>> dataset1.comment='This is the dataset that contains 5';
dataset1 =
numerical: 5
comment: 'This is the dataset that contains 5'