rlowdb

rlowdb is a lightweight, JSON-based database for R, inspired by LowDB from JavaScript. It provides a simple and efficient way to store, retrieve, update, and delete structured data without the need for a full database system.

rlowdb relies on the yyjsonr package, which is extremely fast, to read/write your json database.

Features

• Lightweight & File-Based: Uses JSON for persistent storage.
• Easy-to-Use API: Supports CRUD operations (Create, Read, Update, Delete).
• Flexible Queries: Allows filtering with expressive conditions.
• No External Dependencies: No need for SQL or additional database software.

Installation

You can install rlowdb from CRAN with:

install.packages("rlowdb")

You can also install the development version from Github with:

devtools::install_github("feddelegrand7/rlowdb")

Usage

Initializing the Database

To start using `rlowdb``, create a new database instance by specifying a JSON file:

library(rlowdb)
db <- rlowdb$new(file_path = "DB.json")

If the json file is not available, rlowdb will create it automatically when inserting data.

Verbosity

When creating the instance, you can set the the verbose parameter to TRUE, this way you’ll get an informative message each time you operate on your DB. The default is FALSE.

db <- rlowdb$new(file_path = "DB.json", verbose = FALSE)

Auto Commit

By default, when creating a new instance of rlowdb, the auto_commit parameter will be set to TRUE meaning that each time you make a modification to your DB, the underlying json file will be immediately saved and the new state of the file will overwrite the previous one.

On the other hand if you set the auto_commit parameter to FALSE, it is possible to make changes to your DB but only commit (persist the changes) to your underlying file when you decide to. To do that, you can use the commit() method.

db <- rlowdb$new(file_path = "DB.json", auto_commit = FALSE)

Default Values

You can include default values using the default_values parameter which takes a named list of lists specifying default key-value pairs to be included when inserting new records into the database. The structure follows the format:

# this is just an example, do not run

default_values <- list(
  collection_name = list(
    key_name_1 = value_1,
    key_name_2 = value_2,
    key_name_n = value_n
  )
)

db <- rlowdb$new(file_path = "DB.json",  default_values = default_values) 

• collection_name: The name of the collection (or table) where the default values will apply.
• key_name_n: The name of a field within a record.
• value: The default value to assign to the corresponding field when a new record is inserted.

Pretty output

db <- rlowdb$new(file_path = "DB.json", pretty = FALSE)

When initiating your database, you can set the pretty parameter to TRUE, this way, the json output will be pretty formatted. By default, the pretty parameter is set to FALSE to enhance performance.

Schema

Using the set_schema method, you can defines a validation schema for a specific collection. Once a schema is set, all future insert() and update() operations on that collection will be validated against the specified rules before they are committed to the database.

# Define a schema for the 'users' collection
db$set_schema(collection = "users", list(
  id    = "numeric",
  name  = function(x) is.character(x) && nchar(x) > 0,
  age   = function(x) is.numeric(x) && x >= 0,
  email = NULL  # Optional field
))

# Attempt to insert an invalid record (fails validation)
try(db$insert("users", list(id = "1", name = "")))
#> Error in private$.validate_record(collection, record) : 
#>   Schema validation failed for collection 'users':
#> - Key 'id' must be type 'numeric' (got 'character')
#> - Key 'name' failed validation
#> - Missing required field: 'age'

At any time, you can retrieve the defined schema using the get_schema() method. You can also delete the schema by setting it to NULL:

db$set_schema(collection = "users", NULL)

Inserting Data

The insert method takes two parameters, a collection and a record, think of the collection parameter as a table in the SQL world. Think of the record parameter as a list of names, each name/value pair representing a specific column and it’s value.

Add records to a collection:

db$insert(
  collection = "users", 
  record = list(id = 1, name = "Ali", age = 30)
)
db$insert(
  collection = "users", 
  record = list(id = 2, name = "Bob", age = 25)
)

db$insert(
  collection = "users", 
  record = list(id = 3, name = "Alice", age = 30)
)

Transaction

Using the transaction method, you can insert a set of records and if an error occurs in the process, a rollback will be triggered to restore the initial state of the database. Note that the insertion has to be operated using a function:

db$count("users")
#> [1] 3

db$transaction(function() {
    db$insert("users", list(name = "Zlatan", age = 40))
    db$insert("users", list(name = "Neymar", age = 28))
    stop("some errors")
    db$insert("users", list(name = "Ronaldo", age = 30))
})
#> Error in `value[[3L]]()`:
#> ! Transaction failed: some errors

db$count("users")
#> [1] 3

Retrieving Data

Get all stored data:

db$get_data()
#> $users
#> $users[[1]]
#> $users[[1]]$id
#> [1] 1
#> 
#> $users[[1]]$name
#> [1] "Ali"
#> 
#> $users[[1]]$age
#> [1] 30
#> 
#> 
#> $users[[2]]
#> $users[[2]]$id
#> [1] 2
#> 
#> $users[[2]]$name
#> [1] "Bob"
#> 
#> $users[[2]]$age
#> [1] 25
#> 
#> 
#> $users[[3]]
#> $users[[3]]$id
#> [1] 3
#> 
#> $users[[3]]$name
#> [1] "Alice"
#> 
#> $users[[3]]$age
#> [1] 30

Get data from a specific collection:

db$get_data_collection("users")
#> [[1]]
#> [[1]]$id
#> [1] 1
#> 
#> [[1]]$name
#> [1] "Ali"
#> 
#> [[1]]$age
#> [1] 30
#> 
#> 
#> [[2]]
#> [[2]]$id
#> [1] 2
#> 
#> [[2]]$name
#> [1] "Bob"
#> 
#> [[2]]$age
#> [1] 25
#> 
#> 
#> [[3]]
#> [[3]]$id
#> [1] 3
#> 
#> [[3]]$name
#> [1] "Alice"
#> 
#> [[3]]$age
#> [1] 30

Get data from a specific key:

db$get_data_key("users", "name")
#> [1] "Ali"   "Bob"   "Alice"

Find a specific record:

db$find(collection = "users", key = "id", value = 1)
#> [[1]]
#> [[1]]$id
#> [1] 1
#> 
#> [[1]]$name
#> [1] "Ali"
#> 
#> [[1]]$age
#> [1] 30

Updating Records

Modify existing records:

db$update(
  collection = "users", 
  key = "id", 
  value = 1, 
  new_data = list(age = 31)
)

db$get_data()
#> $users
#> $users[[1]]
#> $users[[1]]$id
#> [1] 1
#> 
#> $users[[1]]$name
#> [1] "Ali"
#> 
#> $users[[1]]$age
#> [1] 31
#> 
#> 
#> $users[[2]]
#> $users[[2]]$id
#> [1] 2
#> 
#> $users[[2]]$name
#> [1] "Bob"
#> 
#> $users[[2]]$age
#> [1] 25
#> 
#> 
#> $users[[3]]
#> $users[[3]]$id
#> [1] 3
#> 
#> $users[[3]]$name
#> [1] "Alice"
#> 
#> $users[[3]]$age
#> [1] 30

The upsert methods allows you to update a record if it exists, otherwise, it will be inserted. Note that the collection and the key need to exist:

db$upsert(
  collection = "users", 
  key = "id", 
  value = 1, 
  new_data = list(age = 25)
)

db$get_data()
#> $users
#> $users[[1]]
#> $users[[1]]$id
#> [1] 1
#> 
#> $users[[1]]$name
#> [1] "Ali"
#> 
#> $users[[1]]$age
#> [1] 25
#> 
#> 
#> $users[[2]]
#> $users[[2]]$id
#> [1] 2
#> 
#> $users[[2]]$name
#> [1] "Bob"
#> 
#> $users[[2]]$age
#> [1] 25
#> 
#> 
#> $users[[3]]
#> $users[[3]]$id
#> [1] 3
#> 
#> $users[[3]]$name
#> [1] "Alice"
#> 
#> $users[[3]]$age
#> [1] 30

db$upsert(
  collection = "users", 
  key = "id", 
  value = 100, 
  new_data = list(age = 25)
)

db$get_data()
#> $users
#> $users[[1]]
#> $users[[1]]$id
#> [1] 1
#> 
#> $users[[1]]$name
#> [1] "Ali"
#> 
#> $users[[1]]$age
#> [1] 25
#> 
#> 
#> $users[[2]]
#> $users[[2]]$id
#> [1] 2
#> 
#> $users[[2]]$name
#> [1] "Bob"
#> 
#> $users[[2]]$age
#> [1] 25
#> 
#> 
#> $users[[3]]
#> $users[[3]]$id
#> [1] 3
#> 
#> $users[[3]]$name
#> [1] "Alice"
#> 
#> $users[[3]]$age
#> [1] 30
#> 
#> 
#> $users[[4]]
#> $users[[4]]$id
#> [1] 100
#> 
#> $users[[4]]$age
#> [1] 25

Deleting Records

db$delete(collection = "users", key = "id", value = 100) 

db$get_data()
#> $users
#> $users[[1]]
#> $users[[1]]$id
#> [1] 1
#> 
#> $users[[1]]$name
#> [1] "Ali"
#> 
#> $users[[1]]$age
#> [1] 25
#> 
#> 
#> $users[[2]]
#> $users[[2]]$id
#> [1] 2
#> 
#> $users[[2]]$name
#> [1] "Bob"
#> 
#> $users[[2]]$age
#> [1] 25
#> 
#> 
#> $users[[3]]
#> $users[[3]]$id
#> [1] 3
#> 
#> $users[[3]]$name
#> [1] "Alice"
#> 
#> $users[[3]]$age
#> [1] 30

Bulk Inserting

You can insert many records at once using the buld_insert method:

db$bulk_insert("users", list(
    list(id = 1, name = "Antoine", age = 52),
    list(id = 2, name = "Omar", age = 23),
    list(id = 3, name = "Nabil", age = 41)
))

Querying Data

Find users older than 25:

db$query(collection = "users", condition = "age > 25")
#> [[1]]
#> [[1]]$id
#> [1] 3
#> 
#> [[1]]$name
#> [1] "Alice"
#> 
#> [[1]]$age
#> [1] 30
#> 
#> 
#> [[2]]
#> [[2]]$id
#> [1] 1
#> 
#> [[2]]$name
#> [1] "Antoine"
#> 
#> [[2]]$age
#> [1] 52
#> 
#> 
#> [[3]]
#> [[3]]$id
#> [1] 3
#> 
#> [[3]]$name
#> [1] "Nabil"
#> 
#> [[3]]$age
#> [1] 41

Query with multiple conditions:

db$query(collection = "users", condition = "age > 20 & id > 1")
#> [[1]]
#> [[1]]$id
#> [1] 2
#> 
#> [[1]]$name
#> [1] "Bob"
#> 
#> [[1]]$age
#> [1] 25
#> 
#> 
#> [[2]]
#> [[2]]$id
#> [1] 3
#> 
#> [[2]]$name
#> [1] "Alice"
#> 
#> [[2]]$age
#> [1] 30
#> 
#> 
#> [[3]]
#> [[3]]$id
#> [1] 2
#> 
#> [[3]]$name
#> [1] "Omar"
#> 
#> [[3]]$age
#> [1] 23
#> 
#> 
#> [[4]]
#> [[4]]$id
#> [1] 3
#> 
#> [[4]]$name
#> [1] "Nabil"
#> 
#> [[4]]$age
#> [1] 41

Filter Data

The filter method allows you to apply a predicate function (a function that returns TRUE or FALSE) in order to get a specific set of records:

db$filter("users", function(x) {
  x$age > 30
})
#> [[1]]
#> [[1]]$id
#> [1] 1
#> 
#> [[1]]$name
#> [1] "Antoine"
#> 
#> [[1]]$age
#> [1] 52
#> 
#> 
#> [[2]]
#> [[2]]$id
#> [1] 3
#> 
#> [[2]]$name
#> [1] "Nabil"
#> 
#> [[2]]$age
#> [1] 41

Searching Data

The search method allows you to search within character fields a specific record. You can also use regex:

db$search("users", "name", "^Ali", ignore.case = FALSE)
#> [[1]]
#> [[1]]$id
#> [1] 1
#> 
#> [[1]]$name
#> [1] "Ali"
#> 
#> [[1]]$age
#> [1] 25
#> 
#> 
#> [[2]]
#> [[2]]$id
#> [1] 3
#> 
#> [[2]]$name
#> [1] "Alice"
#> 
#> [[2]]$age
#> [1] 30

db$search("users", "name", "alice", ignore.case = TRUE)
#> [[1]]
#> [[1]]$id
#> [1] 3
#> 
#> [[1]]$name
#> [1] "Alice"
#> 
#> [[1]]$age
#> [1] 30

Listing the collections

The list_collections method returns the names of the collections within your DB:

db$list_collections()
#> [1] "users"

Counting

Using the count method, you can get the number of records a collection has:

db$count(collection = "users") 
#> [1] 6

Check if exists

It possible to verify if a collection, a key or a value exists within your DB:

db$exists_collection(collection = "users")
#> [1] TRUE

db$exists_collection(collection = "nonexistant")
#> [1] FALSE

db$exists_key(collection = "users", key = "name")
#> [1] TRUE

db$exists_value(
  collection = "users",
  key = "name",
  value = "Alice"
)
#> [1] TRUE

db$exists_value(
  collection = "users",
  key = "name",
  value = "nonexistant"
)
#> [1] FALSE

DB status

Using the status method, you can at each time get some valuable information about the state of your DB:

db$status()
#> - database path: DB.json
#> - database exists: TRUE
#> - auto_commit: TRUE
#> - verbose: FALSE
#> - collections: users
#> - schemas: No schema defined

Clear, Drop Data

It is possible to clear a collection. This will remove all the elements belonging to the collection but not drop the collection it self:

db$insert(collection = "countries", record = list(id = 1, country = "Algeria", continent = "Africa"))

db$insert(collection = "countries", record = list(id = 1, country = "Germany", continent = "Europe"))

db$get_data()
#> $users
#> $users[[1]]
#> $users[[1]]$id
#> [1] 1
#> 
#> $users[[1]]$name
#> [1] "Ali"
#> 
#> $users[[1]]$age
#> [1] 25
#> 
#> 
#> $users[[2]]
#> $users[[2]]$id
#> [1] 2
#> 
#> $users[[2]]$name
#> [1] "Bob"
#> 
#> $users[[2]]$age
#> [1] 25
#> 
#> 
#> $users[[3]]
#> $users[[3]]$id
#> [1] 3
#> 
#> $users[[3]]$name
#> [1] "Alice"
#> 
#> $users[[3]]$age
#> [1] 30
#> 
#> 
#> $users[[4]]
#> $users[[4]]$id
#> [1] 1
#> 
#> $users[[4]]$name
#> [1] "Antoine"
#> 
#> $users[[4]]$age
#> [1] 52
#> 
#> 
#> $users[[5]]
#> $users[[5]]$id
#> [1] 2
#> 
#> $users[[5]]$name
#> [1] "Omar"
#> 
#> $users[[5]]$age
#> [1] 23
#> 
#> 
#> $users[[6]]
#> $users[[6]]$id
#> [1] 3
#> 
#> $users[[6]]$name
#> [1] "Nabil"
#> 
#> $users[[6]]$age
#> [1] 41
#> 
#> 
#> 
#> $countries
#> $countries[[1]]
#> $countries[[1]]$id
#> [1] 1
#> 
#> $countries[[1]]$country
#> [1] "Algeria"
#> 
#> $countries[[1]]$continent
#> [1] "Africa"
#> 
#> 
#> $countries[[2]]
#> $countries[[2]]$id
#> [1] 1
#> 
#> $countries[[2]]$country
#> [1] "Germany"
#> 
#> $countries[[2]]$continent
#> [1] "Europe"

Now, look what happened when we use the clear method on the countries collection:

db$clear("countries")

db$get_data()
#> $users
#> $users[[1]]
#> $users[[1]]$id
#> [1] 1
#> 
#> $users[[1]]$name
#> [1] "Ali"
#> 
#> $users[[1]]$age
#> [1] 25
#> 
#> 
#> $users[[2]]
#> $users[[2]]$id
#> [1] 2
#> 
#> $users[[2]]$name
#> [1] "Bob"
#> 
#> $users[[2]]$age
#> [1] 25
#> 
#> 
#> $users[[3]]
#> $users[[3]]$id
#> [1] 3
#> 
#> $users[[3]]$name
#> [1] "Alice"
#> 
#> $users[[3]]$age
#> [1] 30
#> 
#> 
#> $users[[4]]
#> $users[[4]]$id
#> [1] 1
#> 
#> $users[[4]]$name
#> [1] "Antoine"
#> 
#> $users[[4]]$age
#> [1] 52
#> 
#> 
#> $users[[5]]
#> $users[[5]]$id
#> [1] 2
#> 
#> $users[[5]]$name
#> [1] "Omar"
#> 
#> $users[[5]]$age
#> [1] 23
#> 
#> 
#> $users[[6]]
#> $users[[6]]$id
#> [1] 3
#> 
#> $users[[6]]$name
#> [1] "Nabil"
#> 
#> $users[[6]]$age
#> [1] 41
#> 
#> 
#> 
#> $countries
#> list()

Using the drop method, one can drop a whole collection:

db$drop(collection = "countries")
db$get_data()
#> $users
#> $users[[1]]
#> $users[[1]]$id
#> [1] 1
#> 
#> $users[[1]]$name
#> [1] "Ali"
#> 
#> $users[[1]]$age
#> [1] 25
#> 
#> 
#> $users[[2]]
#> $users[[2]]$id
#> [1] 2
#> 
#> $users[[2]]$name
#> [1] "Bob"
#> 
#> $users[[2]]$age
#> [1] 25
#> 
#> 
#> $users[[3]]
#> $users[[3]]$id
#> [1] 3
#> 
#> $users[[3]]$name
#> [1] "Alice"
#> 
#> $users[[3]]$age
#> [1] 30
#> 
#> 
#> $users[[4]]
#> $users[[4]]$id
#> [1] 1
#> 
#> $users[[4]]$name
#> [1] "Antoine"
#> 
#> $users[[4]]$age
#> [1] 52
#> 
#> 
#> $users[[5]]
#> $users[[5]]$id
#> [1] 2
#> 
#> $users[[5]]$name
#> [1] "Omar"
#> 
#> $users[[5]]$age
#> [1] 23
#> 
#> 
#> $users[[6]]
#> $users[[6]]$id
#> [1] 3
#> 
#> $users[[6]]$name
#> [1] "Nabil"
#> 
#> $users[[6]]$age
#> [1] 41

Finally, drop_all will drop all the collections within your DB:

db$drop_all()
db$get_data()
#> named list()

Creating a Backup

You can create at any time a backup for your database using the backup method:

db$backup("DB_backup.json")

Restoring a database

You can restore a backup database or any preexisting DB using the restore method:

db$restore("DB_backup.json")

Error Handling

rlowdb provides error handling for common issues. For example, attempting to update a collection that does not exist will result in an informative error:

db$update(
  collection = "nonexistant", 
  key = "id",
  value = 1, 
  new_data = list(age = 40)
)  
#> Error in `private$.find_index_by_key()` at rlowdb/R/main.R:207:7:
#> ! Error: Collection 'nonexistant' does not exist.

Future Features

• Support for nested data structures.
• More advanced query capabilities.
• Compatibility with alternative file formats (e.g., CSV, SQLite).

Code of Conduct

Please note that the ralger project is released with a Contributor Code of Conduct. By contributing to this project, you agree to abide by its terms.