I'd like to be able to specify a string, let's say
NSString * pathPattern = /api/elements/:id/subelement/:type
and call a simple function
[pathPattern build:#{#":id" => id, #"subelement" => subelement}]
to generate the URL path.
Obviously I can build a simple category to do this, but does something exist that handles such things in a generic way, and maybe has additional useful features for this kind of thing that I haven't thought of at this time?
Yes, RestKit already injects parameters into path patterns. Internally it uses SOCKit to perform this parameterisation.
It actually uses exactly the format you have in the question and where the parameter names match keys on the supplied object for mapping.
The path pattern can also be used during response mapping to take values back out of the request URL.
Related
While designing the API with with the team a suggestion was forwarded in regards to some complex query parameters that we sent which need to be encoded as objects, arrays of objects, etc. Suppose I have a route GET /resource/ and I want to apply a set of filters directly in the query params. The object literal structure of this filter would be something like
filter: {
field1: {
contains: 'value',
notin: ['value2', 'value3']
},
field2: {
greaterThan: 10
}
}
Encoding this in the url, via a query string parser such as the qs node module that express.js uses internally, would be cheap on the backend. However 1) The generated url is very hard to read, if a client wants to connect with the API he would need to use an encoding library and 2) I don't think I ever encountered the use of query params like this, it looks a little bit of overengineered and I'm not sure how used it is and if it is really safe.
The example above would yield query params such as:
GET /resource/?field1%5Bcontains%5D=value&field1%5Bnotin%5D%5B0%5D=value2&field1%5Bnotin%5D%5B1%5D=value3&field2%5BgreaterThan%5D=10
Does this practice of sending url query parameters that happen to be complex objects have some standards or best practices?
We implemented a different solution for filtering, when the list of possible parameters was very long. We ended up doing it in two steps, posting the filter and returning a filter ID. The filter ID could then be used in the GET query.
We had trouble finding any best practices for this.
Inside an Objective-C method, it is possible to get the selector of the method with the keyword _cmd. Does such a thing exist for the names of arguments?
For example, if I have a method declared as such:
- (void)methodWithAnArgument:(id)foo {
...
}
Is there some sort of construct that would allow me to get access to some sort of string-like representation of the variable name? That is, not the value of foo, but something that actually reflects the variable name "foo" in a local variable inside the method.
This information doesn't appear to be stored in NSInvocation or any of its related classes (NSMethodSignature, etc), so I'm not optimistic this can be done using Apple's frameworks or the runtime. I suspect it might be possible with some sort of compile-time macro, but I'm unfamiliar with C macros so I wouldn't know where to begin.
Edit to contain more information about what I'm actually trying to do.
I'm building a tool to help make working with third-party URL schemes easier. There are two sides to how I want my API to look:
As a consumer of a URL scheme, I can call a method like [twitterHandler showUserWithScreenName:#"someTwitterHandle"];
As a creator of an app with a URL scheme, I can define my URLs in a plist dictionary, whose key-value pairs look something like #"showUserWithScreenName": #"twitter://user?screenName={screenName}".
What I'm working on now is finding the best way to glue these together. The current fully-functioning implementation of showUserWithScreenName: looks something like this:
- (void)showUserWithScreenName:(NSString *)screenName {
[self performCommand:NSStringFromSelector(_cmd) withArguments:#{#"screenName": screenName}];
}
Where performCommand:withArguments: is a method that (besides some other logic) looks up the command key in the plist (in this case "showUserWithScreenName:") and evaluates the value as a template using the passed dictionary as the values to bind.
The problem I'm trying to solve: there are dozens of methods like this that look exactly the same, but just swap out the dictionary definition to contain the correct template params. In every case, the desired dictionary key is the name of the parameter. I'm trying to find a way to minimize my boilerplate.
In practice, I assume I'm going to accept that there will be some boilerplate needed, but I can probably make it ever-so-slightly cleaner thanks to NSDictionaryOfVariableBindings (thanks #CodaFi — I wasn't familiar with that macro!). For the sake of argument, I'm curious if it would be possible to completely metaprogram this using something like forwardInvocation:, which as far as I can tell would require some way to access parameter names.
You can use componentsSeparatedByString: with a : after you get the string from NSStringFromSelector(_cmd) and use your #selector's argument names to put the arguments in the correct order.
You can also take a look at this post, which is describing the method naming conventions in Objective C
How to add params to the MKNetworkOperation. When I use a NSDictionary it does not work because I would like to have something like this:
username=blabla&nr=1&nr=3&nr=4
nr is a list.
So I cannot treat nr as a key because it is not unique.
How can I solve this?
According the MKNetworkkit Multivalued parameters should be possible?
It is beyond me why you are not simply using NSURLConnection, so I can only guess what your third party framework is or is not capable of.
If I read the limitation you describe correctly, one solution that comes to mind is to just device your own scheme, e.g. like this:
username=blabla&nr=1,2,3,5,8,13,21
and then parse the number list yourself.
You can always construct the URL manually. If you pass nil in the 'params' argument of the operationWithPath:params:httpMethod:ssl:, the framework will leave the URL alone and not try and append anything at the end. You can start by using the NSDictionary+RequestEncoding.h methods to encode the initial url on an NSMutableString and then append the rest at the end.
I'm currently working on my first major project in clojure and have run into a question regarding coding style and the most "clojure-esque" way of doing something. Basically I have a function I'm writing which takes in a data structure and a template that the function will try to massage the data structure into. The template structure will look something like this:
{
:key1 (:string (:opt :param))
:key2 (:int (:opt :param))
:key3 (:obj (:tpl :template-structure))
:key4 (:list (:tpl :template-structure))
}
Each key is an atom that will be searched for in the given data structure, and it's value will be attempted to be matched to the type given in the template structure. So it would look for :key1 and check that it's a string, for instance. The return value would be a map that has :key1 pointing to the value from the given data structure (the function could potentially change the value depending on the options given).
In the case of :obj it takes in another template structure, and recursively calls itself on that value and the template structure, and places the result from that in the return. However, if there's an error I want that error returned directly.
Similarly for lists I want it to basically do a map of the function again, except in the case of an error which I want returned directly.
My question is what is the best way to handle these errors? Some simple exception handling would be the easiest way, but I feel that it's not the most functional way. I could try and babysit the errors all the way up the chain with tons of if statements, but that also doesn't seem very sporting. Is there something simple I'm missing or is this just an ugly problem?
You might be interested in schematic, which does pretty similar stuff. You can see how it's used in the tests, and the implementation.
Basically I defined an error function, which returns nil for correctly-formatted data, or a string describing the error. Doing it with exceptions instead would make the plumbing easier, but would make it harder to get the detailed error messages like "[person: [first_name: expected string, got integer]]".
Any good CCK API docs out there? I have seen http://api.audean.com/, but can't find what I want there.
Basically, I need a function that takes a field name and returns what node type has that field. I wrote my own, but would rather make an API call.
CCK is an awesome module but has terrible, outdated documentation. :(
Looking through the module files revealed content_fields($field_name) which may provide the functionality you are looking for.
The function takes in the field name and returns an array of all the settings for that field.
The node type is stored in ['type_name'] so you could write something like the following:
$field = content_fields('field_myfield');
$node_type = $field['type_name'];
That should give you the node type for field_myfield.