Database communication

Serverpod makes it easy to communicate with your database using strictly typed objects without a single SQL line. But, if you need to do more complex tasks, you can always do direct SQL calls. You define your database mappings right in the protocol yaml files.

Database mappings

It's possible to map serializable classes straight to tables in your database. To do this, add the table key to your yaml file:

class: Company
table: company
fields:
  name: String
  foundedDate: DateTime?
  employees: List<Employee>

When running serverpod generate, the database schema will be saved in the generated/tables.pgsql file. You can use this to create the corresponding database tables.

In some cases, you want to save a field to the database, but it should never be sent to the server. You can exclude it from the protocol by adding the database flag to the type.

class: UserData
fields:
  name: String
  password: String?, database

Likewise, if you only want a field to be accessible in the protocol but not stored in the server, you can add the api flag. By default, a field is accessible to both the API and the database.

info

If you use the database or api options the field must be nullable.

Database indexes

For performance reasons, you may want to add indexes to your database tables. You add these in the yaml-files defining the serializable objects.

class: Company
table: company
fields:
  name: String
  foundedDate: DateTime?
  employees: List<Employee>
indexes:
  company_name_idx:
    fields: name

The fields key holds a comma-separated list of column names. In addition, it's possible to add a type key (default is btree), and a unique key (default is false).

Making queries

For the communication to work, you need to have generated serializable classes with the table key set, and the corresponding table must have been created in the database.

Inserting a table row

Insert a new row in the database by calling the insert method of the db field in your Session object.

var myRow = Company(name: 'Serverpod corp.', employees: []);
await Company.insert(session, myRow);

After the object has been inserted, it's id field is set from its row in the database.

Finding a single row

You can find a single row, either by its id or using an expression. You need to pass a reference to the a session in the call. Tables are accessible through generated serializable classes.

var myCompany = await Company.findById(session, companyId);

If no matching row is found, null is returned. You can also search for rows using expressions with the where parameter. The where parameter is a typed expression builder. The builder's parameter, t, contains a description of the table which gives access to the table's columns.

var myCompany = await Company.findSingleRow(
  session,
  where: (t) => t.name.equals('My Company'),
);

Finding multiple rows

To find multiple rows, use the same principle as for finding a single row. Returned will be a List of TableRows.

var companies = await Company.find(
  tCompany,
  where: (t) => t.id < 100,
  limit: 50,
);

Updating a row

To update a row, use the update method. The object that you update must have its id set to a non null value.

var myCompany = await session.db.findById(tCompany, companyId) as Company?;
myCompany.name = 'New name';
await session.db.update(myCompany);

Deleting rows

Deleting a single row works similarly to the update method, but you can also delete rows using the where parameter.

// Delete a single row
await Company.deleteRow(session, myCompany);

// Delete all rows where the company name ends with 'Ltd'
await Company.delete(
  where: (t) => t.name.like('%Ltd'),
);

Creating expressions

To find or delete specific rows, most often, expressions are needed. Serverpod makes it easy to build expressions that are statically type-checked. Columns are referenced using the global table descriptor objects. The table descriptors, t are passed to the expression builder function. The >, >=, <, <=, &, and | operators are overridden to make it easier to work with column values. When using the operators, it's a good practice to place them within a set of parentheses as the precedence rules are not always what would be expected. These are some examples of expressions.

// The name column of the Company table equals 'My company')
t.name.equals('My company')

// Companies founded at or after 2020
t.foundedDate >= DateTime.utc(2020)

// Companies with number of employees between 10 and 100
(t.numEmployees > 10) & (t.numEmployees <= 100)

// Companies that has the founded date set
t.foundedDate.notEquals(null)

Transactions

Docs coming.

Executing raw queries

Sometimes more advanced tasks need to be performed on the database. For those occasions, it's possible to run raw SQL queries on the database. Use the query method. A List<List<dynamic>> will be returned with rows and columns.

var result = await session.db.query('SELECT * FROM mytable WHERE ...');