Im planning to use Leaflet Draw as part of a special wiki with an embedded map. Users should be able to draw geo-objects that are related to one or more pages in the wiki. As the wiki-pages the objects are saved in a database and can be modified by every user.
Problems:
How can i limit the number of editable objects to only one at a time?
How to keep the database consistent if two users are editing the same object at the same time?
How can i generte multi-objects/combine several objects (e.g. polygons) to a super-object (multi-polygon)?
Does anybody know some similiar approches to my idea?
Thanks.
You will have a single FeatureGroup for leaflet.draw's objects that can be edited. Simply figure out which objects will be edited and which won't be and add them to seperate FeatureGroups.
This can be handled in a few ways, maybe have a look around at general database consistency for this.
I'm not sure what you mean, maybe have a look at Well Known Text it might help you with storage here.
Related
I'm currently working on a notes app because I really dislike any notes app that I could find on the app store because the lists you can create are either:
only text
only checkboxes
lines of text followed by checkboxes or vice versa
But by now I found no app (except for Samsung's proprietary Samsung Notes app which only works on Samsung smartphones as it seems) that allows alternating use of lines text and checkboxes.
When thinking about how to implement this properly I had some issues coming up with a proper way of identifying when there is a checkbox and when there should be a line of text. For obvious reasons, just storing text and specifying an identifier like <chkbox> (or something along those lines) is not a good solution because checkboxes should only be placeable by clicking the respective icon. The user should neither be restricted to use the term <chkbox> (because for whatever reason he might want to use it) nor should injections like this be possible.
The best thing that came to my mind up until now was to store each line individually (identified by \n) in a list with dynamic datatype and for each line either store it as text object or string or as checkbox item. Finally, I could simply store the list as one single object in the database. However, I'm unsure whether that's good practice as I could imagine that it makes changes to the list quite cumbersome (e.g. for changing the ticked-value of one single checkbox we would need to store the entire datastructure again instead of just changing one boolean in the database)?
I'm working in Flutter and use Firebase Firestore as my backend/database. Although I'm mostly looking for a general approach/solution to this, with the chosen technologies in mind, is there any solution that would work better than what my recent thoughts are, or is there any serious flaws or drawbacks that I overlooked? Thanks in advance for any constructive input.
We have a need for "Blending of hits from different sources", as per your documentation it is recommended to write a custom-searcher in JAVA. Is there a demo of this written somewhere on Github ? I wouldn't even know where to start :( I understand I can create search "chains" , preferably Asynchronous, and then blend results in JAVA before returning them...but then how would I handle paginations, limits...etc ? This all seems very complicated, for someone who doesn't even know JAVA that much. So, I am hoping someone has already written a demo for this ? Please ? Anyone ?
Thank you so much
EDIT to make my quesion clearer:
We are writing a search engine that fetches data from various websites. Some websites have 10mil indexable items, other websites only 100,000. When we present the results to end user, we want to include results from all our sources ( when match applies ). Let's say 10 results from each of the websites we crawl, so that they all get equal amount of attention on page. If we don't do custom blending, what happens is that the largest website with most items wins all our traffic.
I understand that we can send 10 separate queries to VESPA, and blend the results in our front end, but that seems very inefficient. Thus, the quesion of "Custome Searcher". Thank you so much !
That documentation covers some very advanced use cases which you do not have. Are your sources different Vespa schemas or content clusters? If so Vespa will by default blend the hits returned from each according to their relevance scores so there's nothing you need to do.
The two other most common use-cases are:
Some (or all) the data sources are external, so you need to write a Searcher component to fetch the external data and turn it into a Result.
You want the data to be blended in some custom way (rather than by relevance score). If so you need to exclude the default blending Searcher (com.yahoo.prelude.searcher.BlendingSearcher) and write your own.
If you provide some more information about your use cases I can give you some code examples.
EDIT: Use grouping to solve the need explained under "EDIT" in the question:
Create a "siteid" field when feeding (e.g in document processing).
Use the grouping expression all(group(siteid) each(max(10) output(summary())))
See http://docs.vespa.ai/documentation/grouping.html
We have multiple projects with multiple portlets and need to send an array of objects between them.
Our situation:
One of the porlets is like a "Master-portlet", it will be responsible for all the REST-calls and consume json-data and parse it to Java-Objects.
All the other portlets will receive an array of objects and show them to the user.
Our thoughts and solution:
We wanted to implement this by sending arrays of objects trough events. One of the "smaller" portlets will send an event to the "Master-portlet" and the "Master-portlet" will then answer with a new event and send the right array of objects back.
Our problem:
We dont know how to send arrays of objects trough events. Is this even possible?
Also we are not sure if this is the right way to solve this. Are events ment to send a bigger amount of data?
Is there a better solution for our case? Maybe it would be better to implement a database and all the portlets get the information from there?
Consider portlet events (and portlets) the UI layer of your application. Based on this, judge if the amount of data that you send back and forth makes sense or not. Also, if you closely couple the portlets, you're just hiding the fact that they can only function together - at least a questionable idea. You rather want them to react to common circumstances (events), but not rely on a specific source of events (master portlet) being available.
That being said: The more complex the data is that you send as payload of a JSR-286 event, the easier you run into classloading problems in cases where your portlets are in different webapplications. If you restrict yourself to Java native types (e.g. String, Map, etc) you will omit problems with the classloader.
Typically you want to communicate changes to the current context (e.g. new "current customer" selected - and an identifier) but not all of the particular data (e.g. the new customer's name and order history). The rest of the data typically comes through the business layer anyway.
That's not to say that you absolutely must not couple your portlets - just that my preference is to rather have them very loosely coupled, so that I can add individual small portlets that replace those that I thought of yesterday.
If you have some time, I've covered a bit of this in a webinar last year, I hope that this adds some clarification where I was too vague in this quick answer.
I was wondering if someone could point me in the right direction.
Here is my problem: I have a large form/checklist that I would like to make digital for ease of use.
Thoughts: I would like to use existing tools that would be easy to integrate. My first option is Access 2010.
My question: I would like to enter the questions into a database and then use those entries to auto generate a form that can be used to allow the user to input the actual data into the database. An example would be I have 11 Sections of questions and under each section I have sub-sections that can contain anywhere from 1-... how many every questions we need.
Is it possible to use data stored in an Access database to generate a form with Checkboxes that can be used to input data?
Please point me in the right direction. Obviously there is the option of just creating multiple forms or one big form, but I would like this form to easily be changed etc... Less work more automation.
Thanks,
Alex
Depending on the requirements of your project, this may be quite possible. If you want to use Access as both the back-end and front-end, then you'll need to work within a few limitations:
Because Access combines the user interface and design interface into the same screen, it requires a certain amount of trust that the user can't or won't try to get too creative with changing the data, seeing everyone else's data, changing the design of your form because they are bored, etc. There are ways around these problems, but they can get complicated.
Will all your users be using Window's machines with Access 2010 installed and with the original default settings? If so, good. If not, there may be ways that this could still work.
(There's more, but that's all I can think of right now)
To get started, here's a broad outline:
Make a table for your questions. This table would just have the questions.
Make a form using that question table as the source. Leave the checkboxes and other answer fields unbounded. Include a 'submit' button at the bottom.
The submit button will create a sql query to insert the user's answers into a 2nd table.
If you have any specific questions, we here at SO will be glad to answer them.
In order to dynamically and easily change the number of questions in the sections, what I would do is:
In the main Questions table, add a field called Section to allocate the questions into diffferent ones, and another one Yes/No field to select those that are included (you may also exclude them by leaving the section field empty, as you wish). This will solve the problem of changing the design easily. you probaly will need an admin form in order to do this changes, to avoid touching the tables directly, but this is your decision.
Secondly, in order to allow the users to efectively answer the generated form, you have to ask yourself if you want to accumulate the answer sets, and if you are going to control who answers
I've run into reoccuring problem for which I haven't found any good examples or patterns.
I have one core service that performs all heavy datasbase operations and that sends results to different front ends (html, silverlight/flash, web services etc).
One of the service operation is "GetDocuments", which provides a list of documents based on different filter criterias. If I only had one front-end, I would like to package the result in a list of Document DTOs (Data transfer objects) that just contains the data. However, different front-ends needs different amounts of "metadata". The simples client just needs the document headline and a link reference. Other clients wants a short text snippet of the document, another one also wants a thumbnail and a third wants the name of the author. Its basically all up to the implementation of the GUI what needs to be displayed.
Whats the best way to model this:
As a lot of different DTOs (Document, DocumentWithThumbnail, DocumentWithTextSnippet)
tends to become a lot of classes
As one DTO containing all the data, where the client choose what to display
Lots of unnecessary data sent
As one DTO where certain fields are populated based on what the client requested
Tends to become a very large class that needs to be extended over time
One DTO but with some kind of generic "Metadata" field containing requested metadata.
Or are there other options?
Since I want a high performance service, I need to think about both network load and caching strategies.
Does anyone have any good patterns or practices that might help me?
What I would do is give the front end the ability to request the presence of the wanted metadata ( say getDocument( WITH_THUMBNAILS | WITH_TEXT_SNIPPET ) )
Then this DTO is built with only this requested information.
Adding all the possible metadata is as you said, unacceptable.
I will surely stay with one class defining all the possible methods (getTitle(), getThumbnail()) and if possible it will return a placeholder when the thumbnail was not requested. Something like "Image not available".
If you want to model this like a pattern, take a look at the factory patterns.
Hope this helps you.
Is there any noticable cost to creating a DTO that has all the data any of your views could need and using it everywhere? I would do that, especially since it insulates you from a requirement change down the line to have one of the views incorporate data one of the other views uses
ex. Maybe your silverlight/flash view doesn't show the title itself b/c it's in the thumb now, but they decide they want to sort by it later.
To clarify, I do not necesarily think you need to pass down all of the data every time, but I think your DTO class should define all of them. Just don't fall into the pits of premature optimization or analysis paralysis. Do the simplest thing first, then justify added complexity. Throw it all in and profile it. If the perf is unacceptable, optimize and try again.