Transactions

In transactions, requests to ArangoDB server are committed as a single, logical unit of work (ACID compliant).

Example:

from aioarangodb import ArangoClient

# Initialize the ArangoDB client.
client = ArangoClient()

# Connect to "test" database as root user.
db = await client.db('test', username='root', password='passwd')
col = db.collection('students')

# Begin a transaction. Read and write collections must be declared ahead of
# time. This returns an instance of TransactionDatabase, database-level
# API wrapper tailored specifically for executing transactions.
txn_db = await db.begin_transaction(read=col.name, write=col.name)

# The API wrapper is specific to a single transaction with a unique ID.
txn_db.transaction_id

# Child wrappers are also tailored only for the specific transaction.
txn_aql = txn_db.aql
txn_col = txn_db.collection('students')

# API execution context is always set to "transaction".
assert txn_db.context == 'transaction'
assert txn_aql.context == 'transaction'
assert txn_col.context == 'transaction'

assert '_rev' in await txn_col.insert({'_key': 'Abby'})
assert '_rev' in await txn_col.insert({'_key': 'John'})
assert '_rev' in await txn_col.insert({'_key': 'Mary'})

# Check the transaction status.
await txn_db.transaction_status()

# Commit the transaction.
await txn_db.commit_transaction()
assert await col.has('Abby')
assert await col.has('John')
assert await col.has('Mary')
assert await col.count() == 3

# Begin another transaction. Note that the wrappers above are specific to
# the last transaction and cannot be reused. New ones must be created.
txn_db = db.begin_transaction(read=col.name, write=col.name)
txn_col = txn_db.collection('students')
assert '_rev' in await txn_col.insert({'_key': 'Kate'})
assert '_rev' in await txn_col.insert({'_key': 'Mike'})
assert '_rev' in await txn_col.insert({'_key': 'Lily'})
assert await txn_col.count() == 6

# Abort the transaction
await txn_db.abort_transaction()
assert not await col.has('Kate')
assert not await col.has('Mike')
assert not await col.has('Lily')
assert await col.count() == 3  # transaction is aborted so txn_col cannot be used

See TransactionDatabase for API specification.

Alternatively, you can use arango.database.StandardDatabase.execute_transaction() to run raw Javascript code in a transaction.

Example:

from aioarangodb import ArangoClient

# Initialize the ArangoDB client.
client = ArangoClient()

# Connect to "test" database as root user.
db = await client.db('test', username='root', password='passwd')

# Get the API wrapper for "students" collection.
students = db.collection('students')

# Execute transaction in raw Javascript.
result = await db.execute_transaction(
    command='''
    function () {{
        var db = require('internal').db;
        db.students.save(params.student1);
        if (db.students.count() > 1) {
            db.students.save(params.student2);
        } else {
            db.students.save(params.student3);
        }
        return true;
    }}
    ''',
    params={
        'student1': {'_key': 'Lucy'},
        'student2': {'_key': 'Greg'},
        'student3': {'_key': 'Dona'}
    },
    read='students',  # Specify the collections read.
    write='students'  # Specify the collections written.
)
assert result is True
assert await students.has('Lucy')
assert await students.has('Greg')
assert await students.has('Dona')