I need to find a way to generate a random number each time the REST call is executed.
I have the following GET call:
exec(http("Random execution")
.get("/randomApi")
.queryParam("id", getRandomId()))
}
Obviously it doesn't work as the random number is only generated once and I end up with the same
number whenever this call is executed. I cant use the feeder option as my feeder is already huge and is generated by a 3rd party for each test.
.queryParam takes Expressions as its arguments, and since Expression is an alias for a session function, you can just do...
.queryParam("id", session => getRandomId())
You could also define a second feeder that uses a function to generate the values - no need to update your existing feeder or add another csv file. This would be useful if you had more complicated logic for getting / generating an Id
val idFeeder = Iterator.continually(Map("id" -> Random.nextInt(999999)))
//in your scenario...
.feed(idFeeder)
.exec(http("Random execution")
.get("/randomApi")
.queryParam("id", "${id}")
)
In the spirit of having options, another option you have is to store an object in the session that support toString, which generates whatever you need. It's a nifty trick that you can use for all kinds of things.
object RANDOM_ID {
toString() { return RandomId().toString() }
}
...
exec( _.set( "RANDOM_ID", RANDOM_ID ) )
...
.exec(
http("Random execution")
.get("/randomApi")
.queryParam( "id", "${RANDOM_ID}" )
)
You can apply the same principle to generating random names, addresses, telephone numbers, you name it.
So, which is the better solution? The feeder, or the object in session?
Most of the time, it'll be the feeder, because you control when it is updated. The object in session will be different every time, whereas the feeder solution, you control when the value updates, and then you can reference it multiple times before you change it.
But there may be instances where the stored object solution results in easier to read code, provided you are good with the value changing every time it is accessed. So it's good to know that it is an option.
Related
It seems to be a simple question but I have a hard time to find an answer to it. I already have a project with several parameters (project and database parameters). I would like to obtain the LCA results for several scenarios with my parameters having different values each time. I was thinking of the following simple procedure:
change the parameters' value,
update the exchanges in my project,
calculate the LCA results.
I know that the answer should be in the documentation somewhere, but I have a hard time to understand how I should apply it to my ProjectParameters, DatabaseParameters and ActivityParameters.
Thanks in advance!
EDIT: Thanks to #Nabla, I was able to come up with this:
For ProjectParameter
for pjparam in ProjectParameter.select():
if pjparam.name=='my_param_name':
break
pjparam.amount = 3
pjparam.save()
bw.parameters.recalculate()
For DatabaseParameter
for dbparam in DatabaseParameter.select():
if dbparam.name=='my_param_name':
break
dbparam.amount = 3
dbparam.save()
bw.parameters.recalculate()
For ActivityParameter
for param in ActivityParameter.select():
if param.name=='my_param_name':
break
param.amount = 3
param.save()
param.recalculate_exchanges(param.group)
You could import DatabaseParameter and ActivityParameter iterate until you find the parameter you want to change, update the value, save it and recalculate the exchanges. I think you need to do it in tiers. First you update the project parameters (if any) then the database parameters that may depend on project parameters and then the activity parameters that depend on them.
A simplified case without project parameters:
from bw2data.parameters import ActivityParameter,DatabaseParameter
# find the database parameter to be updated
for dbparam in DatabaseParameter.select():
if (dbparam.database == uncertain_db.name) and (dbparam.name=='foo'):
break
dbparam.amount = 3
dbparam.save()
#there is also this method if foruma depend on something else
#dbparam.recalculate(uncertain_db.name)
# here updating the exchanges of a particular activity (act)
for param in ActivityParameter.select():
if param.group == ":".join(act.key):
param.recalculate_exchanges(param.group)
you may want to update all the activities in the project instead of a single one like in the example. you just need to change the condition when looping through the activity parameters.
I have created cache in my spark application, to refresh few values after every 6 hours.
The code looks as below.
val cachedList: Cache[String, String] = CacheBuilder.newBuilder()
.maximumSize(10)
.expireAfterWrite(refreshTimeInSeconds.toLong, TimeUnit.SECONDS)
.build()
This method gets the items and caches for me.
def prepareUnfilteredAccountList(): Array[String] = {
logger.info("Refreshing the UNFILTERED Accounts List from API")
val unfilteredAccounts = apiService.getElementsToCache().get.map(_.accountNumber).toArray
logger.trace("cached list has been refreshed New List is " +
unfilteredAccounts
}
This method is used to get the cached values into list.
def getUnfilteredList(): Array[String] = {
unfilteredAccounts.get("cached_list", new Callable[String]() {
override def call(): String = {
prepareUnfilteredAccountList().mkString(",")
}
}).split(",")
}
However, i observed that the cache is getting refreshed for every call, instead of getting refreshed after specified time period.
First off, if you want to store a list or an array in a Cache you can do so, there's no need to convert it into a string and then split it back into an array.
Second, maximumSize() configures how many entries are in your cache - by the looks of it your cache only ever has one entry (your list), so specifying a maximum size is meaningless.
Third, if you're only trying to cache one value you might prefer the Suppliers.memoizeWithExperiation() API, which is simpler and less expensive than a Cache.
Fourth, in prepareUnfilteredAccountList() unfilteredAccounts appears to be an array, but in getUnfilteredList() the same variable appears to be a cache. At best this is going to be confusing for you to work with. Use distinct variable names for distinct purposes. It's possible this is the cause of your problems.
All that said calling Cache.get(K, Runnable) should work as you expect - it will invoke the Runnable only if the given key does not already exist in the the cache and has not expired. If that isn't the behavior you're seeing the bug is likely elsewhere in your code. Perhaps your refreshTimeInSeconds is not what you expect, or you're not actually reading the value you're caching, or the cache is actually working as intended and you're misdiagnosing its behavior as erroneous.
For several years I have been using the CGridCellCombo class. It is designed to be used with the CGridCtrl.
Several years ago I did make a request in the comments section for an enhancement but I got no replies.
The basic concept of the CGridCellCombo is that it works with the text value of the cell. Thus, when you present the drop list it will have that value selected. Under normal circumstances this is fine.
But I have places where I am using the combo as a droplist. In some situations it is perfectly fine to continue to use the text value as the go-between.
But is some situations it would have been ideal to know the actual selected index of the combo. When I have a droplist and it is translated into 30 languages, and I need to know the index, I have no choice but to load the possible options for that translation and then examine the cell value and based on the value found in the array I know the index.
It works, but is not very elegant. I did spend a bit of time trying to keep track of the selected index by adding a variable to CInPlaceList and setting it but. I then added a wrapper method to the CGridCellCombo to return that value. But it didn't work.
I wondered if anyone here has a good understanding of the CGridCellCombo class and might be able to advise me in exposing the CComboCell::GetCurSel value.
I know that the CGridCtrl is very old but I am not away of another flexible grid control that is designed for MFC.
The value that is transfered back to the CGridCtrl is choosen in CInPlaceList::EndEdit. The internal message GVN_ENDLABELEDIT is used, and this message always use a text to set it into the grid.
The value is taken here via GetWindowText from the control. Feel free to overwrite this behaviour.
The handler CGridCtrl::OnEndInPlaceEdit again calls OnEndEditCell. All take a string send from GVN_ENDLABELEDIT.
When you want to make a difference between the internal value and the selected value you have to manage this via rewriting the Drawing and selecting. The value in the grid is the GetCurSel value and you have to show something different... There isn't much handling about this in the current code to change.
More information
The key is CInPlaceList::EndEdit(). There is a call to GetWindowText (CInPlaceList is derived from CComboBox), just get the index here. Also in CGridCellCombo::EndEdit you have access to the m_pEditWnd, that is the CInPlaceList object and derived from CComboBox, so you have access here too.
I have found this to be the simplest solution:
int CGridCellCombo::GetSelectedIndex()
{
int iSelectedIndex = CB_ERR;
CString strText = GetText();
for (int iOption = 0; iOption < m_Strings.GetSize(); iOption++)
{
if (strText.CollateNoCase(m_Strings[iOption]) == 0) // Match
{
iSelectedIndex = iOption;
break;
}
}
return iSelectedIndex;
}
I'm writing a REST api in node js that will execute a sql query and send the results;
in the request I need to send the WHERE conditions; ex:
GET 127.0.0.1:5007/users //gets the list of users
GET 127.0.0.1:5007/users
id = 1 //gets the user with id 1
Right now the conditions are passed from the client to the rest api in the request's headers.
In the API I'm using sequelize, an ORM that needs to receive WHERE conditions in a particular form (an object); ex: having the condition:
(x=1 AND (y=2 OR z=3)) OR (x=3 AND y=1)
this needs to be formatted as a nested object:
-- x=1
-- AND -| -- y=2
| -- OR ----|
| -- z=3
-- OR -|
|
| -- x=3
-- AND -|
-- y=1
so the object would be:
Sequelize.or (
Sequelize.and (
{x=1},
Sequelize.or(
{y=2},
{z=3}
)
),
Sequelize.and (
{x=3},
{y=1}
)
)
Now I'm trying to pass a simple string (like "(x=1 AND (y=2 OR z=3)) OR (x=3 AND y=1)"), but then I will need a function on the server that can convert the string in the needed object (this method in my opinion has the advantage that the developer writing the client, can pass the where conditions in a simple way, like using sql, and this method is also indipendent from the used ORM, with no need to change the client if we need to change the server or use a different ORM);
The function to read and convert the conditions' string into an object is giving me headache (I'm trying to write one without success, so if you have some examples about how to do something like this...)
What I would like to get is a route capable of executing almost any kind of sql query and give the results:
now I have a different route for everything:
127.0.0.1:5007/users //to get all users
127.0.0.1:5007/users/1 //to get a single user
127.0.0.1:5007/lastusers //to get user registered in the last month
and so on for the other tables i need to query (one route for every kind of request I need in the client);
instead I would like to have only one route, something like:
127.0.0.1:5007/request
(when calling this route I will pass the table name and the conditions' string)
Do you think this solution would be a good solution or you generally use other ways to handle this kind of things?
Do you have any idea on how to write a function to convert the conditions' string into the desired object?
Any suggestion would be appreciated ;)
I would strongly advise you not to expose any part of your database model to your clients. Doing so means you can't change anything you expose without the risk of breaking the clients. One suggestion as far as what you've supplied is that you can and should use query parameters to cut down on the number of endpoints you've got.
GET /users //to get all users
GET /users?registeredInPastDays=30 //to get user registered in the last month
GET /users/1 //to get a single user
Obviously "registeredInPastDays" should be renamed to something less clumsy .. it's just an example.
As far as the conditions string, there ought to be plenty of parsers available online. The grammar looks very straightforward.
IMHO the main disadvantage of your solution is that you are creating just another API for quering data. Why create sthm from scratch if it is already created? You should use existing mature query API and focus on your business logic rather then inventing sthm new.
For example, you can take query syntax from Odata. Many people have been developing that standard for a long time. They have already considered different use cases and obstacles for query API.
Resources are located with a URI. You can use or mix three ways to address them:
Hierarchically with a sequence of path segments:
/users/john/posts/4711
Non hierarchically with query parameters:
/users/john/posts?minVotes=10&minViews=1000&tags=java
With matrix parameters which affect only one path segment:
/users;country=ukraine/posts
This is normally sufficient enough but it has limitations like the maximum length. In your case a problem is that you can't easily describe and and or conjunctions with query parameters. But you can use a custom or standard query syntax. For instance if you want to find all cars or vehicles from Ford except the Capri with a price between $10000 and $20000 Google uses the search parameter
q=cars+OR+vehicles+%22ford%22+-capri+%2410000..%2420000
(the %22 is a escaped ", the %24 a escaped $).
If this does not work for your case and you want to pass data outside of the URI the format is just a matter of your taste. Adding a custom header like X-Filter may be a valid approach. I would tend to use a POST. Although you just want to query data this is still RESTful if you treat your request as the creation of a search result resource:
POST /search HTTP/1.1
your query-data
Your server should return the newly created resource in the Location header:
HTTP/1.1 201 Created
Location: /search/3
The result can still be cached and you can bookmark it or send the link. The downside is that you need an additional POST.
I am scraping an 90K record database using JSON-RPC and I am trying to put in some basic error checking. I want to start by scraping the database twice using two different settings and adding a prefix to the second scrape. This way I can check to ensure that the two settings are not producing different records (due to dropped updates, etc). I wanted to implement the comparison using a view which compares each document from the first scrape with it's twin produced by the second scrape and then emit the names of records with a difference between them.
However, I cannot quite figure out how to pull in another doc in the view, everything I have read only discusses external docs using the emit() function, which is too late to permit me to compare it. In the example below, the lookup() function would grab the referenced document.
Is this just not possible?
function(doc) {
if(doc._id.slice(0,1)!=='$' && doc._id.slice(0,1)!== "_"){
var otherDoc = lookup('$test" + doc._id);
if(otherDoc){
var keys = doc.value.keys();
var same = true;
keys.forEach(function(key) {
if ((key.slice(0,1) !== '_') && (key.slice(0,1) !=='$') && (key!=='expires')) {
if (!Object.equal(otherDoc[key], doc[key])) {
same = false;
}
}
});
if(!same){
emit(doc._id, 1);
}
}
}
}
Context
You are correct that this is not possible in CouchDB. The whole point of the map function is that it must be idempotent, otherwise you lose all the other nice benefits of a pre-calculated index.
This is why you cannot access external resources in the map function, whether they be other records or the clock. Any time you run a map you must always get the same result if you put the same record into it. Since there are no relationships between records in CouchDB, you cannot promise that this is possible.
Solution
However, you can still achieve your end goal, just be different means. Some possibilities...
Assuming there is some meaningful numeric value in each doc, you could use a view to take the sum of all those values and group them by which import you did ({key: <batch id>, value: <meaningful number>}). Then compare the two numbers in your client or the browser to see if they match.
A brute force approach would be to use a view to pair the docs that should match. Each doc is on a different row, but they're grouped by a common field. Then iterate through the entire index comparing the pairs. This would certainly be the quickest to code and doesn't depend on your application or data.
Implement a validation function to enforce a schema on your data. Just be warned that this will reduce your write throughput since each written record will be piped out of Erlang and into the JS engine. Also, this is only applicable if you're worried about properly formed records instead of their precise content, which might not be the case.
Instead of your different batch jobs creating different docs, have them place them into the same doc. The structure might look like this: { "_id": "something meaningful", "batch_one": { ..data.. }, "batch_two": { ..data.. } } Then your validation function could compare them or you could create a view that indexes all the docs that don't match. All depends on where in your pipeline you want to do the error checking and correction.
Personally I like the last option better, but only if you don't plan to use the database as is in production. Ie., you wouldn't want to carry around all that extra data in each record.
Hope that helps.
Cheers.