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Resource Validation System for Connector Objects

Source: R/connector_check_ressource.R
resource-validation.Rd

This module provides a flexible validation system to verify that resources required by connector objects exist and are accessible. The validation is performed through S3 method dispatch, allowing each connector class to define its own validation logic while providing a consistent interface.

Usage

validate_resource(x)

check_resource(self)

# S3 method for class 'Connector'
check_resource(self)

# S3 method for class 'ConnectorFS'
check_resource(self)

Arguments

x

Connector object to validate.

self

Connector object for method dispatch.

Architecture

The system is built around two main components:

  • validate_resource(): A dispatcher function that finds and executes the appropriate S3 method based on the connector's class

  • check_resource(): A generic S3 method that defines the validation interface for all connector types

Method Resolution

The validation process follows this hierarchy:

  1. Attempt to find a class-specific method (e.g., check_resource.ConnectorFS)

  2. If no specific method exists, fall back to the default check_resource.Connector

  3. Execute the resolved method with appropriate error handling

Available S3 Methods

check_resource.Connector

Default method that performs no validation. Serves as a safe fallback for connector classes without specific validation needs.

check_resource.ConnectorFS

Validates file system resources by checking directory existence using fs::dir_exists(). Throws informative errors for missing directories.

Implementation Guidelines

When implementing new connector classes with resource validation:

  • Define a method following the pattern check_resource.<YourClass>

  • Return NULL on successful validation

  • Use cli::cli_abort() for validation failures to provide consistent error formatting

  • Include call = rlang::caller_env() in error calls for proper error context

Error Handling

The validation system provides robust error handling:

  • Method resolution failures are handled gracefully with fallback to default

  • Validation errors include contextual information about the failing resource

  • Error messages use cli formatting for consistency across the package

Examples

# Basic validation for a file system connector

fs_connector <- try(ConnectorFS$new(path = "doesn_t_exists"), silent = TRUE)
fs_connector
#> [1] "Error in validate_resource(self) : \n  \033[1m\033[22mInvalid file system connector: \033[34mdoesn_t_exists\033[39m does not exist.\n"
#> attr(,"class")
#> [1] "try-error"
#> attr(,"condition")
#> <error/rlang_error>
#> Error in `validate_resource()`:
#> ! Invalid file system connector: doesn_t_exists does not exist.
#> ---
#> Backtrace:
#>      ▆
#>   1. └─pkgdown::build_site_github_pages(new_process = FALSE, install = FALSE)
#>   2.   └─pkgdown::build_site(...)
#>   3.     └─pkgdown:::build_site_local(...)
#>   4.       └─pkgdown::build_reference(...)
#>   5.         ├─pkgdown:::unwrap_purrr_error(...)
#>   6.         │ └─base::withCallingHandlers(...)
#>   7.         └─purrr::map(...)
#>   8.           └─purrr:::map_("list", .x, .f, ..., .progress = .progress)
#>   9.             ├─purrr:::with_indexed_errors(...)
#>  10.             │ └─base::withCallingHandlers(...)
#>  11.             ├─purrr:::call_with_cleanup(...)
#>  12.             └─pkgdown (local) .f(.x[[i]], ...)
#>  13.               ├─base::withCallingHandlers(...)
#>  14.               └─pkgdown:::data_reference_topic(...)
#>  15.                 └─pkgdown:::run_examples(...)
#>  16.                   └─pkgdown:::highlight_examples(code, topic, env = env)
#>  17.                     └─downlit::evaluate_and_highlight(...)
#>  18.                       └─evaluate::evaluate(code, child_env(env), new_device = TRUE, output_handler = output_handler)
#>  19.                         ├─base::withRestarts(...)
#>  20.                         │ └─base (local) withRestartList(expr, restarts)
#>  21.                         │   ├─base (local) withOneRestart(withRestartList(expr, restarts[-nr]), restarts[[nr]])
#>  22.                         │   │ └─base (local) doWithOneRestart(return(expr), restart)
#>  23.                         │   └─base (local) withRestartList(expr, restarts[-nr])
#>  24.                         │     └─base (local) withOneRestart(expr, restarts[[1L]])
#>  25.                         │       └─base (local) doWithOneRestart(return(expr), restart)
#>  26.                         ├─evaluate:::with_handlers(...)
#>  27.                         │ ├─base::eval(call)
#>  28.                         │ │ └─base::eval(call)
#>  29.                         │ └─base::withCallingHandlers(...)
#>  30.                         ├─base::withVisible(eval(expr, envir))
#>  31.                         └─base::eval(expr, envir)
#>  32.                           └─base::eval(expr, envir)
#>  33.                             ├─base::try(ConnectorFS$new(path = "doesn_t_exists"), silent = TRUE)
#>  34.                             │ └─base::tryCatch(...)
#>  35.                             │   └─base (local) tryCatchList(expr, classes, parentenv, handlers)
#>  36.                             │     └─base (local) tryCatchOne(expr, names, parentenv, handlers[[1L]])
#>  37.                             │       └─base (local) doTryCatch(return(expr), name, parentenv, handler)
#>  38.                             └─ConnectorFS$new(path = "doesn_t_exists")
#>  39.                               └─connector (local) initialize(...)
#>  40.                                 └─super$initialize(extra_class = extra_class)
#>  41.                                   └─connector::validate_resource(self)