Module is.codion.framework.model

Package is.codion.framework.model

Interface EntityQueryModel

All Superinterfaces:

Supplier<List<Entity>>

public interface EntityQueryModel
extends Supplier<List<Entity>>

Provides entities fetched from a database. The default query mechanism can be overridden by using query().

 
 Function<EntityQueryModel, List<Entity>> query = queryModel -> {
     EntityConnection connection = queryModel.connectionProvider().connection();
     try {
         return connection.select(Employee.NAME.equalTo("John"));
     }
     catch (DatabaseException e) {
         throw new RuntimeException(e);
     }
 };

 tableModel.queryModel().query().set(query);
 
 

See Also:

• entityQueryModel(EntityConditionModel)

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static interface	EntityQueryModel.AdditionalCondition	Specifies an additional condition supplier.

Method Summary

Modifier and Type	Method	Description
ValueSet<Attribute<?>>	attributes()	Returns the ValueSet controlling which attributes are included when querying entities.
StateObserver	conditionChanged()	When using the default query mechanism, the conditionChanged() state is reset after each successful query.
Value<StateObserver>	conditionEnabled()	It can be necessary to prevent the user from selecting too much data, when working with a large dataset.
State	conditionRequired()	Returns a State controlling whether this query model should query all underlying entities when no query condition has been set.
EntityConditionModel	conditions()
EntityConnectionProvider	connectionProvider()
static EntityQueryModel	entityQueryModel(EntityConditionModel entityConditionModel)
EntityType	entityType()
List<Entity>	get()	Performs a query and returns the result.
EntityQueryModel.AdditionalCondition	having()	Controls the additional HAVING condition, which can be used in conjunction with conditions().
Value<Integer>	limit()	Returns the Value controlling the maximum number of rows to fetch, a null value means all rows should be fetched
Value<OrderBy>	orderBy()	Controls the order by clause to use when selecting the data for this model.
Value<Function<EntityQueryModel,List<Entity>>>	query()	A Value controlling the override query.
void	resetConditionChanged()	Resets the conditionChanged() state, using the current condition.
EntityQueryModel.AdditionalCondition	where()	Controls the additional WHERE condition, which can be used in conjunction with conditions().

Method Details

entityType

EntityType entityType()

Returns:

the type of the entity this query model is based on

connectionProvider

EntityConnectionProvider connectionProvider()

Returns:

the connection provider

get

List<Entity> get()

Performs a query and returns the result. Note that if a query condition is required (conditionRequired()) and the condition is not enabled (conditionEnabled()) an empty list is returned.

Specified by:

get in interface Supplier<List<Entity>>

Returns:

entities selected from the database according to the query condition.

conditions

EntityConditionModel conditions()

Returns:

the EntityConditionModel instance used by this query model

where

EntityQueryModel.AdditionalCondition where()

Controls the additional WHERE condition, which can be used in conjunction with conditions(). The condition supplier may return null in case of no condition. Note that in order for the conditionChanged() StateObserver to indicate a changed condition, the additional condition must be set via Mutable.set(Object), changing the return value of the underlying Supplier instance does not trigger a changed condition.

Returns:

the EntityQueryModel.AdditionalCondition instance controlling the additional WHERE condition

having

EntityQueryModel.AdditionalCondition having()

Controls the additional HAVING condition, which can be used in conjunction with conditions(). The condition supplier may return null in case of no condition. Note that in order for the conditionChanged() StateObserver to indicate a changed condition, the additional condition must be set via Mutable.set(Object), changing the return value of the underlying Supplier instance does not trigger a changed condition.

Returns:

the EntityQueryModel.AdditionalCondition instance controlling the additional HAVING condition

conditionRequired

State conditionRequired()

Returns a State controlling whether this query model should query all underlying entities when no query condition has been set. Setting this value to 'true' prevents all rows from being fetched by accident, when no condition has been set, which is recommended for queries with a large underlying dataset.

Returns:

a State controlling whether this query model requires a query condition

See Also:

• conditionEnabled()

conditionChanged

StateObserver conditionChanged()

When using the default query mechanism, the conditionChanged() state is reset after each successful query.

Returns:

a StateObserver indicating if the search condition has changed since last reset

See Also:

• resetConditionChanged()

resetConditionChanged

void resetConditionChanged()

Resets the conditionChanged() state, using the current condition.

attributes

ValueSet<Attribute<?>> attributes()

Returns the ValueSet controlling which attributes are included when querying entities. Note that an empty ValueSet indicates that the default select attributes should be used.

Returns:

the ValueSet controlling the selected attributes

limit

Value<Integer> limit()

Returns the Value controlling the maximum number of rows to fetch, a null value means all rows should be fetched

Returns:

the Value controlling the query limit

orderBy

Value<OrderBy> orderBy()

Controls the order by clause to use when selecting the data for this model. Setting this value to null reverts back to the default order by for the underlying entity, if one has been specified

Returns:

the Value controlling the order by clause

See Also:

• EntityDefinition.orderBy()

conditionEnabled

Value<StateObserver> conditionEnabled()

It can be necessary to prevent the user from selecting too much data, when working with a large dataset. This can be done by enabling the conditionRequired() State, which prevents a refresh as long as the StateObserver controlled via this method is disabled. The default StateObserver is simply TableConditionModel.enabled(). Override for a more fine grained control, such as requiring a specific column condition to be enabled.

Returns:

the Value controlling the StateObserver specifying if enough conditions are enabled for a safe refresh

See Also:

• conditionRequired()

query

Value<Function<EntityQueryModel,List<Entity>>> query()

A Value controlling the override query. Use this to replace the default query.

Returns:

the Value controlling the query override

entityQueryModel

static EntityQueryModel entityQueryModel(EntityConditionModel entityConditionModel)

Parameters:

entityConditionModel - the EntityConditionModel

Returns:

a new EntityQueryModel instance based on the given EntityConditionModel