An introduction to U1db
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U1DB is a platform-agnostic database API designed for synchronizing JSON document databases across devices, facilitating user-specific data storage. It is document-oriented, allowing dynamic creation and retrieval of documents without predefined fields. Developers can implement querying and indexing to efficiently manage and sync data using U1DB within their applications.
![(c) 2013 Canonical
U1Db is document-oriented
> In U1Db databases store JSON documents
> Documents don’t need a predefined list of fields
{ "key": "value" }
{ "firstname": "Jan", "surname": "Molby", "position": "midfield" }
{ "department": "Department of redundancy department",
"managers": [
{ "name": "Mary", "phone_number": "12345" },
{ "name": "Katherine" },
{ "name": "Rob", "phone_number": "54321" } ]
}
U1Db basics](https://image.slidesharecdn.com/anintroductiontou1db-140708161152-phpapp01/85/An-introduction-to-U1db-4-320.jpg)
![(c) 2013 Canonical
Querying: the Index
> An Index defines what fields can be filtered using a Query
> Used to retrieve documents other than by doc ID
> An index is created from ‘’index expressions’‘, which name one
or more fields in the document
import U1db 1.0 as U1db
U1db.Index {
id: by_place
database: aDatabase
expression: ["place"] // Use dot notation for nested fields
}
U1Db for app developers](https://image.slidesharecdn.com/anintroductiontou1db-140708161152-phpapp01/85/An-introduction-to-U1db-9-320.jpg)
![(c) 2013 Canonical
Querying: the Query
> Once an index has been defined, the query is used to retrieve the data
> Can be used directly as a model by other QML elements (e.g. ListView)
> “Starts with” queries with wildcards are also supported
import U1db 1.0 as U1db
U1db.Query {
id: places
index: by_place
query: [ { "*" } ] // Could also be "Barc*" for further filtering
}
U1Db for app developers](https://image.slidesharecdn.com/anintroductiontou1db-140708161152-phpapp01/85/An-introduction-to-U1db-10-320.jpg)
An introduction to U1db
- 1. An introduction to U1Db David Planella @ Ubuntu Online Summit, June 2014
- 3. (c) 2013 Canonical U1Db in a nutshell > U1DB is a database API for synchronised databases of JSON documents > Enables apps to store documents and sync them across devices > Implementations are platform-specific, the API is platform-agnostic > Simple to use > Schemaless - more flexibility and faster development > Intended for user-specific data U1Db basics
- 4. (c) 2013 Canonical U1Db is document-oriented > In U1Db databases store JSON documents > Documents don’t need a predefined list of fields { "key": "value" } { "firstname": "Jan", "surname": "Molby", "position": "midfield" } { "department": "Department of redundancy department", "managers": [ { "name": "Mary", "phone_number": "12345" }, { "name": "Katherine" }, { "name": "Rob", "phone_number": "54321" } ] } U1Db basics
- 5. (c) 2013 Canonical U1Db elements > Document storage and retrieval > Covers the basic creation, retrieval and edition of documents > Database, Document > Querying > Retrieval of a subset of documents based on certain criteria > Index, Query > Sync > Synchronization of data across devices via a U1Db server > Synchronizer U1Db basics
- 6. > U1Db for app developers
- 7. (c) 2013 Canonical Document storage and retrieval: the Database > Provides the permanent storage for the app’s data > Can be used directly as a model by other QML elements (e.g. ListView) import U1db 1.0 as U1db U1db.Database { id: aDatabase path: "aDatabase.u1db" } U1Db for app developers
- 8. (c) 2013 Canonical Document storage and retrieval: the Document > A database will generally contain multiple JSON-oriented documents > Documents can be created dynamically at runtime import U1db 1.0 as U1db U1db.Document { id: aDocument database: aDatabase docId: "lastPlace" create: true defaults: { "place": "Barcelona" } } U1Db for app developers
- 9. (c) 2013 Canonical Querying: the Index > An Index defines what fields can be filtered using a Query > Used to retrieve documents other than by doc ID > An index is created from ‘’index expressions’‘, which name one or more fields in the document import U1db 1.0 as U1db U1db.Index { id: by_place database: aDatabase expression: ["place"] // Use dot notation for nested fields } U1Db for app developers
- 10. (c) 2013 Canonical Querying: the Query > Once an index has been defined, the query is used to retrieve the data > Can be used directly as a model by other QML elements (e.g. ListView) > “Starts with” queries with wildcards are also supported import U1db 1.0 as U1db U1db.Query { id: places index: by_place query: [ { "*" } ] // Could also be "Barc*" for further filtering } U1Db for app developers
- 11. > U1Db demo
- 12. Thank you and stay in touch! > David Planella <david.planella@ubuntu.com> > +DavidPlanella · @dplanella > developer.ubuntu.com > @ubuntuappdev > gplus.to/ubuntuappdev > facebook.com/ubuntuappdev