Create a model factory function

Usage

base_model(
  fields = list(),
  ...,
  .model_pre_init = NULL,
  .model_post_init = NULL,
  .validators_before = list(),
  .validators_after = list(),
  .strict_args_order = FALSE,
  .allow_na = FALSE,
  .extra = c("ignore", "allow", "forbid")
)

Arguments

fields: A named list of field definitions.
...: Named arguments of field definitions. Normally either fields or ... is supplied.
.model_pre_init: A callback function that is executed before the type checks.
.model_post_init: A callback function that is executed after the type checks.
.validators_before: A named list of field validators that are executed before the type checks.
.validators_after: A named list of field validators that are executed after the type checks.
.strict_args_order: If set to TRUE, the .x parameter of the returned model factory function will be the last function argument. This is useful if you want to pass the arguments unnamed.
.allow_na: Whether to allow NA values for all fields.
.extra: Whether to allow extra fields without type check.

Value

A model factory function.

Examples

# ---
# Models
my_model <- base_model(
  a = is.integer,
  b = is.integer,
  txt = is.character
)

# Succeeds
my_model(a = 1L, b = 2L, txt = "My awesome model")
#> $a
#> [1] 1
#> 
#> $b
#> [1] 2
#> 
#> $txt
#> [1] "My awesome model"
#> 

# Fails
try(my_model(a = 1, b = 2L, txt = "My awesome model"))
#> Error in my_model(a = 1, b = 2L, txt = "My awesome model") : 
#>   Type check(s) failed
#> ---
#> Type check failed for 'a'
#> value:  num 1
#> type: double
#> class: numeric
#> length: 1
#> expected: .Primitive("is.integer")

# ---
# Functions
f <- function(a, b) {
  check_args(a = is.integer, b = is.integer)
  a + b
}

# Succeeds
f(4L, 5L)
#> [1] 9

# Fails
try(f(4, 5))
#> Error in base_model(fields)(.x = func_env) : Type check(s) failed
#> ---
#> Type check failed for 'a'
#> value:  num 4
#> type: double
#> class: numeric
#> length: 1
#> expected: .Primitive("is.integer")
#> ---
#> Type check failed for 'b'
#> value:  num 5
#> type: double
#> class: numeric
#> length: 1
#> expected: .Primitive("is.integer")

# ---
# Data frames
df <- data.frame(
  id = 1:2,
  name = c("Donald", "Lee"),
  surname = c("Byrd", "Morgan")
)

df_model <- base_model(
  id = is.integer,
  name = is.character,
  surname = is.character,
  full_name = is.character,
  .model_pre_init = function(obj) {
    obj$full_name <- paste(obj$name, obj$surname)
    return(obj)
  }
)

# Succeeds
df_model(.x = df)
#>   id   name surname   full_name
#> 1  1 Donald    Byrd Donald Byrd
#> 2  2    Lee  Morgan  Lee Morgan

# Fails
df$id <- NULL
try(df_model(.x = df))
#> Error in df_model(.x = df) : Type check(s) failed
#> ---
#> Type check failed for 'id'
#> value:  NULL
#> type: NULL
#> class: NULL
#> length: 0
#> expected: .Primitive("is.integer")