Allow local caching of API calls

[MarkEdmondson1234]

In now for mock tests, why not be available for all API requests? cache long running API fetches that can restart where a 500 error crops up

[MarkEdmondson1234]

Working on googleAnalyticsR tests https://github.com/MarkEdmondson1234/googleAnalyticsR/issues/76 - now to try the others

[MarkEdmondson1234]

Need to have easy way to turn off cache for API calls that can''t be e.g. task queue checks, something like gar_skip_cache()

[MarkEdmondson1234]

Hmm but task queues do need to be cached when READY. Its going to need an argument and changes to the API function code, perhaps a new flag for gar_api_generator()

Pass a function to check? If req$task$status != "READY" ? Its pre-parsing. Only cache when response meets special condition.

Usually the function is something like

cache_condition <- function(req){
  if(req$status == 200){
     TRUE
 } else {
  FALSE
}
}

but you should have option to pass custom such as:

cache_condition <- function(req){
  if(req$content$task$status == "DONE"){
     TRUE
 } else {
  FALSE
}
}

[MarkEdmondson1234]

Obviously there is already an R package made by hadley for this https://github.com/r-lib/memoise

[MarkEdmondson1234]

I think this works r-lib/memoise#46