dizzbase_client 0.0.6

Flutter client for the dizzbase node.js realtime database backend.

example/example.md

Examples

Full flutter API demo app

Download a full flutter demo app for dizzbase at: https://github.com/dizzweb-GmbH/dizzbase_flutter_demo

The demo app illustrates all examples from below. It also contains SQL scripts to setup a demo database on PostgreSQL. Refer to the README.md file of the demo app for instructions.

Initialization

Initialize the dizzbase client in main():

void main() {
runApp(const MyApp());
DizzbaseConnection.configureConnection("http://localhost:3000", "my-security-token");
}

For each widget the requires streamed updates, create/dispose a DizzbaseConnection:

@override
void initState() {
    dizzbaseClient = DizzbaseConnection();
    super.initState();
}

@override
void dispose() {
    // IMPORTANT!
    dizzbaseClient.dispose();
    super.dispose();
}

Retrieve data with real-time updates for use with StreamBuilder:

Create a DizzbaseConnection (here: myDizzbaseConnection) object in the initState() override of the widget. Use it as follows to retrieve data that is being updated real-time:

StreamBuilder<List<Map<String, dynamic>>>(
stream: myDizzbaseConnection.streamFromQuery(DizzbaseQuery(table: MainTable("employee", pkey: 3))),
builder: ((context, snapshot) {
    if (snapshot.hasData)
    {
    return Text ("Employee \"${snapshot.data![0]['employee_name']}\" uses the email address \"${snapshot.data![0]['employee_email']}\".");
    }
    return Text ("Waiting for inforation on employee number 3...");
})),



// Demo of how a list of orders is automatically updated when a new order is added.
stream: myDizzbaseConnection.streamFromQuery(DizzbaseQuery(
    table: MainTable("order"), 
    joinedTables: [JoinedTable('employee', joinToTableOrAlias: 'order', foreignKey:  'sales_rep_id' )],
    filters: [Filter('employee', 'employee_id', 2)])
    //...

// Search with a LIKE statement.
stream: myDizzbaseConnection.streamFromQuery(DizzbaseQuery(table: MainTable("employee"), filters: [Filter('employee', 'employee_email', '%hotmail%', comparison: 'LIKE')])
// ...

// Complex query      
stream: myDizzbaseConnection.streamFromQuery(DizzbaseQuery(
    table:
    MainTable('order'),
    joinedTables:
    [
    // Automatic JOIN: This will include all columns, and the JOIN to the MainTable will be added automatically using the constraint information in the database
    JoinedTable('customer'), 
    // Join the same table two time, so we need to add aliases. 
    // Observe that the columns for tables with aliases are named differently in the output table - "seller_employee_name" instead of just "employee_name"
    JoinedTable('employee', joinToTableOrAlias: 'order', foreignKey: 'sales_rep_id', columns: ['employee_name', 'employee_email'], alias: 'seller'),
    JoinedTable('employee', joinToTableOrAlias: 'order', foreignKey: 'services_rep_id', columns: ['employee_name'], alias: 'consultant'),
    ],
    sortFields: 
    [
    // Note the the alias is used for sorting, rather than the table name (as the table is part of two joins)
    SortField('seller', 'employee_name', ascending: false), 
    SortField('order', 'order_id', ascending: false), 
    ],
    filters: 
    [
    Filter ('order', 'order_revenue', 50, comparison: ">="),
    ]
)
//...

UPDATE/DELETE/INSERT Transactions

Use the DizzbaseUpdate, DizzbaseInsert, DizzbaseDelete classes with the DizzbaseConnection().updateTransaction, DizzbaseConnection().insertTransaction, DizzbaseConnection().deleteTransaction methods like so:

DizzbaseConnection().updateTransaction(
    DizzbaseUpdate(table: "employee", fields: ["employee_name", "employee_email"], 
    values: [_controllerName.text, _controllerEmail.text], filters: [Filter('employee', 'employee_id', 2)]))
    // ERROR HANDLING and show how many rows were updated:
    .then((result) {
    if (result["error"]!= "") { throw Exception(result["error"]); }
    setState(() => rowsAffected = result["rowCount"]);
    });

Use DizzbaseConnection.directSQLTransaction() to send any custom SQL statement and receive the result as a future.