rlowdb (version 0.2.0)

rlowdb: rlowdb: A Simple JSON-Based Database in R

Description

The `rlowdb` class provides a lightweight, JSON-based database solution for storing and managing structured data in R. It supports CRUD operations (Create, Read, Update, Delete) and enables querying with custom functions.

Methods

Public methods

• rlowdb$new()

• rlowdb$commit()

• rlowdb$get_data()

• rlowdb$get_data_collection()

• rlowdb$get_data_key()

• rlowdb$insert()

• rlowdb$find()

• rlowdb$update()

• rlowdb$upsert()

• rlowdb$delete()

• rlowdb$query()

• rlowdb$filter()

• rlowdb$drop()

• rlowdb$drop_all()

• rlowdb$clear()

• rlowdb$count()

• rlowdb$list_collections()

• rlowdb$exists_collection()

• rlowdb$exists_key()

• rlowdb$exists_value()

• rlowdb$transaction()

• rlowdb$restore()

• rlowdb$backup()

• rlowdb$search()

• rlowdb$bulk_insert()

• rlowdb$status()

• rlowdb$set_auto_commit()

• rlowdb$set_verbose()

• rlowdb$rename_collection()

• rlowdb$list_keys()

• rlowdb$count_values()

• rlowdb$insert_default_values()

• rlowdb$clone_collection()

• rlowdb$sample_records()

• rlowdb$set_schema()

• rlowdb$get_schema()

• rlowdb$clone()

---

Method new()

Initialize the database, loading data from a JSON file. If the file does not exist, an empty database is created.

Usage

rlowdb$new(
  file_path,
  default_values = list(),
  auto_commit = TRUE,
  verbose = FALSE,
  pretty = FALSE
)

Arguments

file_path

The path to the JSON file that stores the database.

default_values

A list of named list with the format: list(collection_name = list(key_name_1 = value, key_name_2 = value, ..., key_name_n = value)) containing the default values that will be inserted each time the `insert` method is called. Note that the default_values will not override the existing records. Default is an empty list (`list()`).

auto_commit

whether to update the DB automatically each time there's an insertion, an update or a deletion. Defaults to TRUE.s Note that you can use the `commit` method to update the DB manually.

verbose

If TRUE, will print informative messages to the console. Defaults to FALSE

pretty

Use pretty = FALSE for compact JSON, which is more efficient for data transmission and storage. TRUE for a human readable format. Defaults to FALSE.

---

Method commit()

Update the DB with the operated changes.

Usage

rlowdb$commit()

---

Method get_data()

Retrieve all stored data.

Usage

rlowdb$get_data()

Returns

A list containing all database records.

Examples

db <- rlowdb$new("database.json")
db$insert("users", list(id = 1, name = "Alice"))
db$get_data()
unlink("database.json")

---

Method get_data_collection()

Retrieve data from a specific collection.

Usage

rlowdb$get_data_collection(collection)

Arguments

collection

The name of the collection

Returns

A list containing a specific collection's records.

Examples

db <- rlowdb$new("database.json")
db$insert("users", list(id = 1, name = "Alice"))
db$get_data_collection("users")
unlink("database.json")

---

Method get_data_key()

Retrieve the records of a specific key within a collection

Usage

rlowdb$get_data_key(collection, key)

Arguments

collection

The name of the collection

key

The key name

Returns

A vector/list containing a specific key's records.

Examples

db <- rlowdb$new("database.json")
db$insert("users", list(id = 1, name = "Alice"))
db$insert("users", list(id = 2, name = "Omar"))
db$get_data_key("users", "name")
unlink("database.json")

---

Method insert()

Insert a new record into a specified collection.

Usage

rlowdb$insert(collection, record)

Arguments

collection

The collection name (a string).

record

A named list representing the record to insert.

Examples

db <- rlowdb$new("database.json", default_values = list(
  "users" = list("active" = TRUE)
 )
)
db$insert("users", list(id = 1, name = "Alice"))
unlink("database.json")

---

Method find()

Find records in a collection that match a given key-value pair.

Usage

rlowdb$find(collection, key, value)

Arguments

collection

The collection name (a string).

key

The field name to search for.

value

The value to match.

Returns

A list of matching records. Returns an empty list if no match is found.

Examples

db <- rlowdb$new("database.json")
db$insert("users", list(id = 1, name = "Alice"))
db$find("users", "id", 1)
unlink("database.json")

---

Method update()

Update existing records in a collection.

Usage

rlowdb$update(collection, key, value, new_data)

Arguments

collection

The collection name.

key

The field name to search for.

value

The value to match.

new_data

A named list containing the updated data.

Examples

db <- rlowdb$new("database.json")
db$insert("users", list(id = 1, name = "Alice"))
db$update("users", "id", 1, list(name = "Alice Updated"))
unlink("database.json")

---

Method upsert()

If a record exists, update it; otherwise, insert a new record. Note that in order to use the method, the 'collection' has to exist

Usage

rlowdb$upsert(collection, key, value, new_data)

Arguments

collection

The collection name.

key

The field name to search for.

value

The value to match.

new_data

A named list containing the updated data.

Examples

db <- rlowdb$new("database.json")
db$insert("users", list(id = 100, name = "Coconut"))
db$upsert("users", "id", 1, list(name = "Alice Updated"))
unlink("database.json")

---

Method delete()

Delete records from a collection that match a given key-value pair.

Usage

rlowdb$delete(collection, key, value)

Arguments

collection

The collection name.

key

The field name to search for.

value

The value to match.

Examples

db <- rlowdb$new("database.json")
db$insert("users", list(id = 1, name = "Alice"))
db$delete("users", "id", 1)
db$get_data()
unlink("database.json")

---

Method query()

Query a collection using a condition string. This function allows filtering records from a collection using a condition string that is evaluated dynamically. The condition supports multiple logical expressions using standard R operators (e.g., `>`, `<`, `==`, `&`, `|`).

Usage

rlowdb$query(collection, condition = NULL)

Arguments

collection

The collection name (a string).

condition

A string representing a logical condition for filtering records. - Supports comparisons (`>`, `<`, `>=`, `<=`, `==`, `!=`). - Allows logical operators (`&` for AND, `|` for OR). - Example: `"views > 200 & id > 2"`. - If `NULL` or an empty string (`""`), returns all records.

Returns

A list of records that satisfy the condition. If no records match, returns an empty list.

Examples

db <- rlowdb$new("database.json")
db$insert("posts", list(id = 1, title = "LowDB in R", views = 100))
db$insert("posts", list(id = 2, title = "Data Management", views = 250))
db$insert("posts", list(id = 3, title = "Advanced R", views = 300))
# Query posts with views > 200 AND id > 2
db$query("posts", "views > 200 & id > 2")
# Query posts with views > 100 OR id == 1
db$query("posts", "views > 100 | id == 1")
# Query all posts (no condition)
db$query("posts", "")
unlink("database.json")

---

Method filter()

Filter Records Using a Custom Function This method applies a user-defined function to filter records in a specified collection. The function should take a record as input and return `TRUE` for records that should be included in the result and `FALSE` for records that should be excluded.

Usage

rlowdb$filter(collection, filter_fn)

Arguments

collection

A character string specifying the name of the collection.

filter_fn

A function that takes a record (a list) as input and returns `TRUE` or `FALSE`.

Returns

A list of records that satisfy the filtering condition.

Examples

db <- rlowdb$new("database.json")
db$insert("users", list(name = "Delta", age = 25))
db$insert("users", list(name = "Gamma", age = 36))
# Find users older than 30
db$filter("users", function(record) record$age > 30)
unlink("database.json")

---

Method drop()

Just like DROP TABLE in SQL, drops a complete collection.

Usage

rlowdb$drop(collection)

Arguments

collection

The collection name.

Examples

db <- rlowdb$new("database.json")
db$insert("users", list(name = "Delta", age = 25))
db$drop("users")
db$get_data()
unlink("database.json")

---

Method drop_all()

Drop all the collections available in your JSON file DB

Usage

rlowdb$drop_all()

Examples

db <- rlowdb$new("database.json")
db$insert("users", list(name = "Delta", age = 25))
db$insert("consumers", list(name = "Teta", age = 22))
db$drop_all()
db$get_data()
unlink("database.json")

---

Method clear()

Removes all records from a collection without deleting the collection itself

Usage

rlowdb$clear(collection)

Arguments

collection

the collection name

Examples

db <- rlowdb$new("database.json")
db$insert("users", list(name = "Delta", age = 25))
db$insert("consumers", list(name = "Teta", age = 22))
db$clear("users")
db$get_data()
unlink("database.json")

---

Method count()

Count the number of records in a collection

Usage

rlowdb$count(collection)

Arguments

collection

the collection name

Returns

numeric

Examples

db <- rlowdb$new("database.json")
db$insert("users", list(name = "Delta", age = 25))
db$insert("users", list(name = "Gamma", age = 36))
db$count("users")
unlink("database.json")

---

Method list_collections()

List the available collections

Usage

rlowdb$list_collections()

Returns

character

Examples

db <- rlowdb$new("database.json")
db$insert("users", list(name = "Delta", age = 25))
db$insert("consumers", list(name = "Teta", age = 22))
db$list_collections()
unlink("database.json")

---

Method exists_collection()

Check if a collection exists.

Usage

rlowdb$exists_collection(collection)

Arguments

collection

The collection name

Returns

TRUE if the collection exists, FALSE otherwise

Examples

db <- rlowdb$new("database.json")
db$insert("users", list(name = "Delta", age = 25))
db$insert("consumers", list(name = "Teta", age = 22))
db$exists_collection("users")
unlink("database.json")

---

Method exists_key()

Check if a key exists within a specific collection.

Usage

rlowdb$exists_key(collection, key)

Arguments

collection

The collection name

key

The key name

Returns

TRUE if the key exists, FALSE otherwise

Examples

db <- rlowdb$new("database.json")
db$insert("users", list(name = "Delta", age = 25))
db$insert("consumers", list(name = "Teta", age = 22))
db$exists_key("users", "name")
unlink("database.json")

---

Method exists_value()

Check if a value exists within a specific collection/key combination.

Usage

rlowdb$exists_value(collection, key, value)

Arguments

collection

The collection name

key

The key name

value

The value to look for

Returns

TRUE if the value exists, FALSE otherwise

Examples

db <- rlowdb$new("database.json")
db$insert("users", list(name = "Delta", age = 25))
db$insert("consumers", list(name = "Teta", age = 22))
db$exists_value("users", "name", "Delta")
unlink("database.json")

---

Method transaction()

Perform a Transaction with Rollback on Failure

This method executes a sequence of operations as a transaction. If any operation fails, it rolls back all changes to maintain data integrity.

Usage

rlowdb$transaction(transaction_fn)

Arguments

transaction_fn

A function that performs operations on `self`. It should not return a value.

Examples

db <- rlowdb$new("database.json")
db$insert("users", list(name = "Delta", age = 25))
db$count("users")
db$transaction(function() {
  db$insert("users", list(name = "Zlatan", age = 40))
  db$insert("users", list(name = "Neymar", age = 28))
  # if an error is raised, a rollback will happen and
  # the records won't be inserted
})
db$count("users")
unlink("database.json")

---

Method restore()

Load a JSON backup and replace the current database.

Usage

rlowdb$restore(backup_path)

Arguments

backup_path

The path of the backup JSON file. Allow users to quickly backup their database.

---

Method backup()

Usage

rlowdb$backup(backup_path)

Arguments

backup_path

The path of the backup JSON file

---

Method search()

Search Records in a Collection

This method searches for records in a collection where a specified key's value contains a given search term.

Usage

rlowdb$search(collection, key, term, ignore.case = FALSE)

Arguments

collection

A character string specifying the name of the collection.

key

A character string specifying the field to search within.

term

A character string specifying the term to search for.

ignore.case

A logical value indicating whether the search should be case-insensitive (default: `FALSE`).

Returns

A list of matching records. Returns an empty list if no matches are found.

Examples

db <- rlowdb$new("database.json")
db$insert("users", list(id = 1, name = "Alice"))
db$insert("users", list(id = 2, name = "Bob"))
db$insert("users", list(id = 3, name = "alice"))
# Case-sensitive search
db$search("users", "name", "Alice", ignore.case = FALSE)
# Case-insensitive search
db$search("users", "name", "alice", ignore.case = TRUE)
unlink("database.json")

---

Method bulk_insert()

Insert Multiple Records into a Collection

This method inserts multiple records into a specified collection at once. Each record should be a named list representing an entry in the collection.

Usage

rlowdb$bulk_insert(collection, records)

Arguments

collection

A character string specifying the name of the collection.

records

A list of named lists, where each named list represents a record to insert.

Examples

db <- rlowdb$new("database.json")
db$bulk_insert("users", list(
  list(id = 1, name = "Alice", age = 25),
  list(id = 2, name = "Bob", age = 32),
  list(id = 3, name = "Charlie", age = 40)
))
db$count("users")
unlink("database.json")

---

Method status()

Provides some useful information about the database

Usage

rlowdb$status()

---

Method set_auto_commit()

Set the auto_commit value

Usage

rlowdb$set_auto_commit(auto_commit)

Arguments

auto_commit

TRUE will update automatically the JSON by each insertion/update/delete. If FALSE, you'll need to use the commit method whenever you want to commit your changes to the JSON DB.

---

Method set_verbose()

Set the verbose value.

Usage

rlowdb$set_verbose(verbose)

Arguments

verbose

If TRUE, informative messages will be printed to the console.

---

Method rename_collection()

Allows you to rename an existing collection in the database. It checks if the specified collection exists before attempting to rename it.

Usage

rlowdb$rename_collection(collection_name, new_collection_name)

Arguments

collection_name

A character string representing the current name of the collection to be renamed.

new_collection_name

A character string representing the new name for the collection.

Examples

db <- rlowdb$new("database.json")
db$bulk_insert("users", list(
  list(id = 1, name = "Alice", age = 25),
  list(id = 2, name = "Bob", age = 32),
  list(id = 3, name = "Charlie", age = 40)
))
db$list_collections()
db$rename_collection("users", "customers")
db$list_collections()
unlink("database.json")

---

Method list_keys()

Retrieves the names (keys) of all keys within a given collection.

Usage

rlowdb$list_keys(collection)

Arguments

collection

The collection name

Returns

A character vector containing the unique keys (field names) present across all records in the collection.

Examples

db <- rlowdb$new("database.json")
db$bulk_insert("users", list(
  list(id = 1, name = "Alice", age = 25),
  list(id = 2, name = "Bob", age = 32),
  list(id = 3, name = "Charlie")
))
db$list_keys("users")
unlink("database.json")

---

Method count_values()

Count Occurrences of a Key's Values in a Collection

Usage

rlowdb$count_values(collection, key)

Arguments

collection

The collection name

key

The key name

Returns

A table (a frequency count) of the values associated with the specified key, showing the number of occurrences of each unique value. If the key does not exist, an error is thrown.

Examples

db <- rlowdb$new("database.json")
db$bulk_insert("users", list(
  list(id = 1, name = "Alice", age = 25),
  list(id = 2, name = "Bob", age = 32),
  list(id = 3, name = NA),
  list(id = 4, name = NA)
))
db$count_values("users", "name")
unlink("database.json")

---

Method insert_default_values()

Add Default Values to Records in a Collection

Ensures that all records in a collection have specific default values for certain keys. If a key is missing, the default value is added. Optionally, existing values can be replaced with defaults.

Usage

rlowdb$insert_default_values(collection, defaults, replace_existing = FALSE)

Arguments

collection

The collection name.

defaults

A named list of default values to add.

replace_existing

Logical; if `TRUE`, replaces existing values with defaults. If `FALSE`, only adds missing keys. Defaults to `FALSE`.

Returns

Updates the collection in place, ensuring consistency of data.

Examples

db <- rlowdb$new("database.json")
db$bulk_insert("users", list(
  list(name = "Alice", age = 30),
  list(name = "Bob"),
  list(name = "Charlie", age = 25, role = "admin")
))
# Add defaults without replacing existing values
db$insert_default_values("users", list(role = "guest", active = TRUE))
# Add defaults and replace existing values
db$insert_default_values("users", list(role = "guest", active = TRUE), replace_existing = TRUE)
unlink("database.json")

---

Method clone_collection()

Clone an existing collection to a new collection with a different name. This creates an exact copy of the original collection's records under the new name.

Usage

rlowdb$clone_collection(from, to)

Arguments

from

The name of the source collection to clone.

to

The name of the new collection.

overwrite

If FALSE (default), will abort if target collection exists. If TRUE, will overwrite existing target collection.

Examples

db <- rlowdb$new("database.json")
db$insert("users", list(id = 1, name = "Alice"))
db$clone_collection("users", "users_backup")
db$list_collections()
unlink("database.json")

---

Method sample_records()

Randomly sample records from a collection

Usage

rlowdb$sample_records(collection, n = 1, replace = FALSE, seed = NULL)

Arguments

collection

The name of the collection to sample from

n

Number of records to sample. If n > collection size, returns all records with a warning.

replace

Should sampling be with replacement? Default FALSE

seed

Optional random seed for reproducible sampling

Returns

A list of sampled records

Examples

db <- rlowdb$new("database.json")
db$insert("users", list(id = 1, name = "Alice"))
db$insert("users", list(id = 2, name = "Bob"))
db$insert("users", list(id = 3, name = "Charlie"))
# Sample 2 records without replacement
db$sample_records("users", n = 2)
# Sample with replacement
db$sample_records("users", n = 5, replace = TRUE)
# Reproducible sampling with seed
db$sample_records("users", n = 2, seed = 123)
unlink("database.json")

---

Method set_schema()

Set schema for a collection to validate future inserts/updates

Usage

rlowdb$set_schema(collection, schema)

Arguments

collection

The collection name

schema

A named list where: - Names are field names - Values can be: * A type string ("character", "numeric", etc.) * A function that returns TRUE/FALSE * A vector of allowed values * NULL to make the field optional

Examples

db <- rlowdb$new("database.json")
# Define schema before inserting
db$set_schema("users", list(
  id = "numeric",
  name = function(x) is.character(x) && nchar(x) > 0,
  age = function(x) is.numeric(x) && x >= 0,
  email = NULL  # Optional
))
# This will fail validation:
try(db$insert("users", list(id = "1", name = "")))

---

Method get_schema()

Retrieve the schema for a specific collection

Usage

rlowdb$get_schema(collection)

Arguments

collection

The collection name

Returns

list

---

Method clone()

The objects of this class are cloneable with this method.

Usage

rlowdb$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

Examples

## ------------------------------------------------
## Method `rlowdb$get_data`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$insert("users", list(id = 1, name = "Alice"))
db$get_data()
unlink("database.json")

## ------------------------------------------------
## Method `rlowdb$get_data_collection`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$insert("users", list(id = 1, name = "Alice"))
db$get_data_collection("users")
unlink("database.json")

## ------------------------------------------------
## Method `rlowdb$get_data_key`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$insert("users", list(id = 1, name = "Alice"))
db$insert("users", list(id = 2, name = "Omar"))
db$get_data_key("users", "name")
unlink("database.json")

## ------------------------------------------------
## Method `rlowdb$insert`
## ------------------------------------------------

db <- rlowdb$new("database.json", default_values = list(
  "users" = list("active" = TRUE)
 )
)
db$insert("users", list(id = 1, name = "Alice"))
unlink("database.json")


## ------------------------------------------------
## Method `rlowdb$find`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$insert("users", list(id = 1, name = "Alice"))
db$find("users", "id", 1)
unlink("database.json")


## ------------------------------------------------
## Method `rlowdb$update`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$insert("users", list(id = 1, name = "Alice"))
db$update("users", "id", 1, list(name = "Alice Updated"))
unlink("database.json")


## ------------------------------------------------
## Method `rlowdb$upsert`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$insert("users", list(id = 100, name = "Coconut"))
db$upsert("users", "id", 1, list(name = "Alice Updated"))
unlink("database.json")


## ------------------------------------------------
## Method `rlowdb$delete`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$insert("users", list(id = 1, name = "Alice"))
db$delete("users", "id", 1)
db$get_data()
unlink("database.json")


## ------------------------------------------------
## Method `rlowdb$query`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$insert("posts", list(id = 1, title = "LowDB in R", views = 100))
db$insert("posts", list(id = 2, title = "Data Management", views = 250))
db$insert("posts", list(id = 3, title = "Advanced R", views = 300))

# Query posts with views > 200 AND id > 2
db$query("posts", "views > 200 & id > 2")

# Query posts with views > 100 OR id == 1
db$query("posts", "views > 100 | id == 1")

# Query all posts (no condition)
db$query("posts", "")

unlink("database.json")

## ------------------------------------------------
## Method `rlowdb$filter`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$insert("users", list(name = "Delta", age = 25))
db$insert("users", list(name = "Gamma", age = 36))
# Find users older than 30
db$filter("users", function(record) record$age > 30)
unlink("database.json")

## ------------------------------------------------
## Method `rlowdb$drop`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$insert("users", list(name = "Delta", age = 25))
db$drop("users")
db$get_data()
unlink("database.json")

## ------------------------------------------------
## Method `rlowdb$drop_all`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$insert("users", list(name = "Delta", age = 25))
db$insert("consumers", list(name = "Teta", age = 22))
db$drop_all()
db$get_data()
unlink("database.json")

## ------------------------------------------------
## Method `rlowdb$clear`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$insert("users", list(name = "Delta", age = 25))
db$insert("consumers", list(name = "Teta", age = 22))
db$clear("users")
db$get_data()
unlink("database.json")

## ------------------------------------------------
## Method `rlowdb$count`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$insert("users", list(name = "Delta", age = 25))
db$insert("users", list(name = "Gamma", age = 36))
db$count("users")
unlink("database.json")

## ------------------------------------------------
## Method `rlowdb$list_collections`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$insert("users", list(name = "Delta", age = 25))
db$insert("consumers", list(name = "Teta", age = 22))
db$list_collections()
unlink("database.json")

## ------------------------------------------------
## Method `rlowdb$exists_collection`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$insert("users", list(name = "Delta", age = 25))
db$insert("consumers", list(name = "Teta", age = 22))
db$exists_collection("users")
unlink("database.json")

## ------------------------------------------------
## Method `rlowdb$exists_key`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$insert("users", list(name = "Delta", age = 25))
db$insert("consumers", list(name = "Teta", age = 22))
db$exists_key("users", "name")
unlink("database.json")

## ------------------------------------------------
## Method `rlowdb$exists_value`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$insert("users", list(name = "Delta", age = 25))
db$insert("consumers", list(name = "Teta", age = 22))
db$exists_value("users", "name", "Delta")
unlink("database.json")

## ------------------------------------------------
## Method `rlowdb$transaction`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$insert("users", list(name = "Delta", age = 25))
db$count("users")
db$transaction(function() {
  db$insert("users", list(name = "Zlatan", age = 40))
  db$insert("users", list(name = "Neymar", age = 28))
  # if an error is raised, a rollback will happen and
  # the records won't be inserted
})
db$count("users")
unlink("database.json")

## ------------------------------------------------
## Method `rlowdb$search`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$insert("users", list(id = 1, name = "Alice"))
db$insert("users", list(id = 2, name = "Bob"))
db$insert("users", list(id = 3, name = "alice"))

# Case-sensitive search
db$search("users", "name", "Alice", ignore.case = FALSE)

# Case-insensitive search
db$search("users", "name", "alice", ignore.case = TRUE)
unlink("database.json")

## ------------------------------------------------
## Method `rlowdb$bulk_insert`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$bulk_insert("users", list(
  list(id = 1, name = "Alice", age = 25),
  list(id = 2, name = "Bob", age = 32),
  list(id = 3, name = "Charlie", age = 40)
))
db$count("users")
unlink("database.json")

## ------------------------------------------------
## Method `rlowdb$rename_collection`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$bulk_insert("users", list(
  list(id = 1, name = "Alice", age = 25),
  list(id = 2, name = "Bob", age = 32),
  list(id = 3, name = "Charlie", age = 40)
))
db$list_collections()
db$rename_collection("users", "customers")
db$list_collections()
unlink("database.json")


## ------------------------------------------------
## Method `rlowdb$list_keys`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$bulk_insert("users", list(
  list(id = 1, name = "Alice", age = 25),
  list(id = 2, name = "Bob", age = 32),
  list(id = 3, name = "Charlie")
))
db$list_keys("users")
unlink("database.json")


## ------------------------------------------------
## Method `rlowdb$count_values`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$bulk_insert("users", list(
  list(id = 1, name = "Alice", age = 25),
  list(id = 2, name = "Bob", age = 32),
  list(id = 3, name = NA),
  list(id = 4, name = NA)
))
db$count_values("users", "name")
unlink("database.json")

## ------------------------------------------------
## Method `rlowdb$insert_default_values`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$bulk_insert("users", list(
  list(name = "Alice", age = 30),
  list(name = "Bob"),
  list(name = "Charlie", age = 25, role = "admin")
))

# Add defaults without replacing existing values
db$insert_default_values("users", list(role = "guest", active = TRUE))

# Add defaults and replace existing values
db$insert_default_values("users", list(role = "guest", active = TRUE), replace_existing = TRUE)

unlink("database.json")

## ------------------------------------------------
## Method `rlowdb$clone_collection`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$insert("users", list(id = 1, name = "Alice"))
db$clone_collection("users", "users_backup")
db$list_collections()
unlink("database.json")

## ------------------------------------------------
## Method `rlowdb$sample_records`
## ------------------------------------------------

db <- rlowdb$new("database.json")
db$insert("users", list(id = 1, name = "Alice"))
db$insert("users", list(id = 2, name = "Bob"))
db$insert("users", list(id = 3, name = "Charlie"))

# Sample 2 records without replacement
db$sample_records("users", n = 2)

# Sample with replacement
db$sample_records("users", n = 5, replace = TRUE)

# Reproducible sampling with seed
db$sample_records("users", n = 2, seed = 123)
unlink("database.json")

## ------------------------------------------------
## Method `rlowdb$set_schema`
## ------------------------------------------------

db <- rlowdb$new("database.json")

# Define schema before inserting
db$set_schema("users", list(
  id = "numeric",
  name = function(x) is.character(x) && nchar(x) > 0,
  age = function(x) is.numeric(x) && x >= 0,
  email = NULL  # Optional
))

# This will fail validation:
try(db$insert("users", list(id = "1", name = "")))