doubledb

doubledb

An on disk database that indexes everything for fast querying.

Installation

npm install --save doubledb

Usage

import createDoubledb from 'doubledb';
const doubledb = await createDoubledb('./data');

doubledb.insert({
  id: undefined, // defaults to uuid, must be unique
  firstName: 'Joe',
  lastName: 'Bloggs',
  stats: {
    wins: 10,
    loses: 5
  },
  skills: ['cooking', 'running']
});

doubledb.get(record.id);
doubledb.find('firstName', 'Joe');
doubledb.find('stats.wins', 10);
doubledb.find('skills', 'cooking');
doubledb.find('firstName', v => v.startsWith('J'), { skip: 20, gt: 'J', lt: 'K' });
doubledb.filter('firstName', 'Joe');
doubledb.filter('firstName', v => v.startsWith('J'));
doubledb.filter('firstName', v => v.startsWith('J'), { limit: 10, skip: 20, gt: 'J', lt: 'K' });
doubledb.replace(record.id, { firstName: 'Joe', lastName: 'Bloggs' });
doubledb.patch(record.id, { firstName: 'Bob' });
doubledb.remove(record.id);

.get(id)

Get a single record by it's .id property.

If a record is found, the whole record will be returned. If no record is found, undefined will be returned.

.find(field, value, { skip })

Quickly find a single record by any field (use.dot.notation.for.nested.properties) and it's exact value.

If multiple records exist, a skip option can be provided to ignore the first number of finds.

If a record is found, the whole record will be returned. If no record is found, undefined will be returned.

.find(field, matcherFunction: (value: string) => boolean), { limit, skip, gt, lt, gte, lte })

Slow find a single record by any field and test against a matcherFunction.

If multiple records exist:

• a skip option can be provided to ignore the first number of finds.
• a limit option can be provided to stop after number of finds.

Find using a matcherFunction will work without a gt and lt, but the indexing will be pretty useless, as it will need to scan every single record.

You should provide a gt and/or lt to let the indexer know where to begin/end.

For example, the query below will scan every first name from A all the way to Z

doubledb.find('firstName', v => v.startsWith('Jo'))

Let's tell it to start from Jo.

doubledb.find('firstName', v => v.startsWith('Jo'), { gt: 'Jo' })

This will skip all indexes lower than Jo. However if it can't find any records, it will keep checking, even if the firstName is Zelda

So we should help the indexer by giving it a lt.

doubledb.find('firstName', v => v.startsWith('Jo'), { gt: 'Jo', lt: 'K' })

Let's look at some more examples:

doubledb.find('favouriteNumber', v => v > 5 && v < 10, { gt: 5, lt: 10 })
doubledb.find('firstName', v => ['Dave', 'Peter'].includes(v), { gt: 'Dave', lte: 'Peter' })

If a record is found, the whole record will be returned. If no record is found, undefined will be returned.

.filter(field, matcherFunction: (value: string) => boolean), { limit, skip, gt, lt, gte, lte })

This works the exact same as .find but will return an array.

If records are found, an array will be returned containing every complete found record. If no records are found, an empty array will be returned.

.replace(key, object)

Completely replace a key with a new object, losing all previous fields in the record.

.patch(key, object)

Merge the new object in with the existing record.

For example, if the following record exists:

{
  "id": "1",
  "firstName": "Joe",
  "lastName": "Bloggs"
}

And you run the following .patch.

doubledb.patch('1', { fullName: 'Joe Bloggs' })

The final record will be:

{
  "id": "1",
  "firstName": "Joe",
  "lastName": "Bloggs",
  "fullName": "Joe Bloggs"
}

.remove(key)

Query the database using a complex query object. This method allows for advanced querying using a combination of fields and operators.

.query(queryObject)

Query the database using a complex query object. This method allows for advanced querying using a combination of fields and operators.

Example:

const records = await doubledb.query({
  location: 'London',
  category: 'b',
  $or: [
    { firstName: { $eq: 'Joe' } },
    { firstName: { $eq: 'joe' } }
  ]
});

The queryObject can contain various fields and operators to filter the records. The following operators are supported:

Operators:

• $eq: Equal to a value.
• $ne: Not equal to a value.
• $gt: Greater than a value.
• $gte: Greater than or equal to a value.
• $lt: Less than a value.
• $lte: Less than or equal to a value.
• $in: Value is in the provided array.
• $nin: Value is not in the provided array.
• $all: Array contains all the provided values.
• $exists: Field exists or does not exist.
• $not: Negates the condition.

Example Usage of Operators:

const records = await doubledb.query({
  age: { $gte: 18, $lt: 30 },
  status: { $in: ['active', 'pending'] },
  $or: [
    { role: { $eq: 'admin' } },
    { role: { $eq: 'user' } }
  ],
  preferences: { $exists: true }
});

How Operators Work:

• $eq: Matches documents where the field is equal to the specified value.
• $ne: Matches documents where the field is not equal to the specified value.
• $gt / $gte: Matches documents where the field is greater than (or greater than or equal to) the specified value.
• $lt / $lte: Matches documents where the field is less than (or less than or equal to) the specified value.
• $in: Matches documents where the field value is in the specified array.
• $nin: Matches documents where the field value is not in the specified array.
• $all: Matches documents where the array field contains all the specified values.
• $exists: Matches documents where the field exists (or does not exist if set to false).
• $not: Matches documents that do not match the specified condition.

This query method is powerful and allows combining multiple conditions and operators to fetch the desired records from the database.