My goal is very simple and I would guess it is a very common goal among web developers.
I am creating a Rails (5.1) application, and I simply want to use AJAX to get the value of a specific cell in a specific row of a specific table in my database (later I am going to use that value to highlight some text on the current page in the user's browser).
I have not been able to find any documentation online explaining how to do this. As I said, it seems like a basic task to ask of jquery and ajax, so I'm confused as to why I'm having so much trouble figuring it out.
For concreteness, say I have a table called 'animals', and I want to get the value of the column 'species' for the animal with 'id' = 99.
How can I construct an AJAX call to query the database for the value of 'species' for the 'animal' with 'id' = 99 .
Though some DBs provide a REST API, what we commonly do is define a route in the app to pull and return data from the DB.
So:
Add a route
Add a controller/action for that route
In that action, fetch the data from the DB and render it in your preferred format
On the client-side, make the AJAX call to that controller/action and do something with the response.
Related
I'm running a local server playing around with an API using Django. I have a model called 'Users' populated with a few objects, and am using DefaultRouter.
I want to know what the URL would be if I were to DELETE a specific object from this model. For example, if I wanted to GET a user with an ID of 1 in this model, the URL would be: "localhost:8000/Users/1/". What would the equivalent be to DELETE this user?
I found an explanation of this on the REST API website (below), however, I don't understand what any of the syntaxes means.
What is {prefix}, {url_path}, {lookup} and [.format]? If anyone could provide an example of what this might be using a localhost that would be really helpful.
Thanks
Let us take an example of an API (URL) to update book data with id (pk) being 10. It would look something like this:
URL: http://www.example.com/api/v1/book/10/
Method: PUT/PATCH
With some data associated.
If you want to delete you just need to change method to DELETE instead of put or patch.
Regarding your second question lets compare the url with the parameters.
prefix: http://www.example.com/api/v1/book
lookup: 10
format: It specifies what type of data do you expect when you hit the API. Generally it is considered to be json.
url_path: In general, every thing after look up except query string is considered to be url_path.
I am doing an HTTP GET request to /maximo/oslc/os/mxsr and using the oslc.select query string parameter to choose:
*,doclinks{*},worklog{*},rel.commlog{*},rel.woactivity{*,rel.woactivity{*}}
This lets me get related data, including related worklogs, but the worklog does not include the 'description_longdescription' field.
The only way I seem to be able to get that field is if I do a separate HTTP GET to query a worklog id directly through /maxrest/rest/mbo/worklog . Then it provides the description_longdescription field.
I understand this field is stored separately through the linked longdescription table, but I was hoping to get the data through the "next gen" oslc api with one http get request.
I've tried putting in 'worklog{*,description_longdescription}', as I read somewhere that longdescription is a "non-persistent" field and must be explicitly named for inclusion, but it had no effect.
I figured out that for the /maximo/oslc/os/mxsr object in the API, I needed to reference the related MODIFYWORKLOG object through the rel.modifyworklog syntax in the oslc.select query string:
oslc.select=*,doclinks{*},rel.modifyworklog{*,description_longdescription},rel.commlog{*},rel.woactivity{*,rel.woactivity{*}}
I also had to explicitly name the non-persistent field description_longdescription for it to be included.
Ref. for the "rel." syntax: https://developer.ibm.com/static/site-id/155/maximodev/restguide/Maximo_Nextgen_REST_API.html#_querying_maximo_asset_management_by_using_the_rest_api
I'm trying to filter my users list by comparing two parameters
query="EmployeeData.EmployeeID=externalId"
EmployeeData.EmployeeID is a custom schema that is populated, with a cron job, with the same value as externalId.
Of course I let the cron do the field copy only if necessary, this is the reason I'm trying to filtering the users list.
In the way i wrote seems that the query trying to looking for a value "externalId" into the EmployeeData.EmployeeID ignoring that "externalId" is a even a field
any suggestion?
The way your code is written, the query sent to Google's servers is as you correctly guessed the following:
EmployeeData.EmployeeID=externalId where your actual externalId is not sent but rather the string "externalId".
To replace this string for the actual value of your variable, you can use what is called "string concatenation" 1. To do it, you just need to modify your code as shown below:
query="EmployeeData.EmployeeID=" + externalId;
This way, the query will be sent as you need to Google's servers.
In my class based view I am handling a post request (which is an AJAX call).I am inserting some data in a database table and returning some json to the frontend.
def post(self,request,*args,**kwargs):
result_data = {}
doc = kwargs['doc']
doc_obj = Document.objects.get_document(doc)
doc_id = doc_obj.doc_id
reference_obj = Reference.objects.save_to_db(request,doc_id)
friendly_name = reference_obj.friendly_name
result_data['friendly_name'] = friendly_name
return HttpResponse(json.dumps(result_data),content_type='application/json')
My question is that is this the right way of handling a post request?My doubt arises here - I am writing some data into database and returning a json of properties of the same data I have written to the database.
Should I do it differently, ie first storing some data in database and returning just id of the row and again making GET request on the same URL?
I would say if it is an API, it is best to minimize the number of queries by returning the whole object the way you did. In case it is to serve a web user interface, it is simpler to return the id and get the rest of the data, if it needs to be displayed, from the client itself.
Either way is fine. The gain is negligible. I have also seen applications give a local positive feedback and then replace with a negative one if the request was unsuccessful. The technique can improve responsiveness, which is always appreciated.
Django-rest-framework returns the json of the inserted object, so i would think it reasonable to copy that behaviour.
i'm working in a symfony project and using sfPropelPager to show a paged list of elements.
The problem is that with a great amount of data to list (i.e. thousands of registers) it makes a query to the database for each page to show!!!! That means about 100 extra queries in my case, and that is unacceptable.
Showing some of my code: the function that returns the pager object
$pager = new sfPropelPager('MyTable',sfConfig::get('sfPropelPagerLines'));
$c = new Criteria();
$c->add('my_table_field',$value);
$c->addDescendingOrderByColumn('date');
$pager->setCriteria($c);
$pager->init();
return $pager;
So, please, if you know a way to get all the results with only one query, it would be a great solution for my problem. Otherwise i must implement that list with an ajax call for every page the user wants to see
Thank you very much for your time.
I'm not sure to get your problem but, anyway, avoid the use of Criteria. Try to make queries with the ModelCriteria API: http://www.propelorm.org/reference/model-criteria.html.
For each paginated page, a query to the database will be done, this is the standard behavior for all pagers I know. If it's related to related objects (assuming you want to display information from relations), you may want to create a query that links those objects before to paginate, that way you'll get one query per page for all your data to display.
Read this doc for instance: http://www.propelorm.org/documentation/03-basic-crud.html#query_termination_methods
At last i did'nt get a solution for the problem, i had to implement the list via AJAX call, calling to a function that returns the requested page, so at the load of the page, no query for this list is slowing the user experience.
Thank you anyway to help me :)