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Codion Application Framework
/*
* This file is part of Codion.
*
* Codion is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Codion is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Codion. If not, see
* {@code
* Function> 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 #entityQueryModel(EntityConditionModel)
*/
public interface EntityQueryModel extends Supplier> {
/**
* @return the type of the entity this query model is based on
*/
EntityType entityType();
/**
* @return the connection provider
*/
EntityConnectionProvider connectionProvider();
/**
* Performs a query and returns the result.
* Note that if a query condition is required ({@link #conditionRequired()})
* and the condition is not enabled ({@link #conditionEnabled()}) an empty list is returned.
* @return entities selected from the database according to the query condition.
*/
@Override
List get();
/**
* @return the {@link EntityConditionModel} instance used by this query model
*/
EntityConditionModel conditions();
/**
* Controls the additional WHERE condition, which can be used in conjunction with {@link #conditions()}.
* The condition supplier may return null in case of no condition.
* Note that in order for the {@link #conditionChanged()} {@link StateObserver} to indicate
* a changed condition, the additional condition must be set via {@link AdditionalCondition#set(Object)},
* changing the return value of the underlying {@link Supplier} instance does not trigger a changed condition.
* @return the {@link AdditionalCondition} instance controlling the additional WHERE condition
*/
AdditionalCondition where();
/**
* Controls the additional HAVING condition, which can be used in conjunction with {@link #conditions()}.
* The condition supplier may return null in case of no condition.
* Note that in order for the {@link #conditionChanged()} {@link StateObserver} to indicate
* a changed condition, the additional condition must be set via {@link AdditionalCondition#set(Object)},
* changing the return value of the underlying {@link Supplier} instance does not trigger a changed condition.
* @return the {@link AdditionalCondition} instance controlling the additional HAVING condition
*/
AdditionalCondition having();
/**
* Returns a {@link 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.
* @return a {@link State} controlling whether this query model requires a query condition
* @see #conditionEnabled()
*/
State conditionRequired();
/**
* When using the default query mechanism, the {@link #conditionChanged()} state is reset after each successful query.
* @return a {@link StateObserver} indicating if the search condition has changed since last reset
* @see #resetConditionChanged()
*/
StateObserver conditionChanged();
/**
* Resets the {@link #conditionChanged()} state, using the current condition.
*/
void resetConditionChanged();
/**
* Returns the {@link ValueSet} controlling which attributes are included when querying entities.
* Note that an empty {@link ValueSet} indicates that the default select attributes should be used.
* @return the {@link ValueSet} controlling the selected attributes
*/
ValueSet> attributes();
/**
* Returns the {@link Value} controlling the maximum number of rows to fetch, a null value means all rows should be fetched
* @return the {@link Value} controlling the query limit
*/
Value limit();
/**
* 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
* @return the {@link Value} controlling the order by clause
* @see EntityDefinition#orderBy()
*/
Value orderBy();
/**
* 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 {@link EntityQueryModel#conditionRequired()} {@link State}, which prevents a refresh as long as the
* {@link StateObserver} controlled via this method is disabled. The default {@link StateObserver} is simply {@link EntityConditionModel#enabled()}.
* Override for a more fine grained control, such as requiring a specific column condition to be enabled.
* @return the {@link Value} controlling the {@link StateObserver} specifying if enough conditions are enabled for a safe refresh
* @see #conditionRequired()
*/
Value conditionEnabled();
/**
* A {@link Value} controlling the override query. Use this to replace the default query.
* @return the {@link Value} controlling the query override
*/
Value>> query();
/**
* @param entityConditionModel the {@link EntityConditionModel}
* @return a new {@link EntityQueryModel} instance based on the given {@link EntityConditionModel}
*/
static EntityQueryModel entityQueryModel(EntityConditionModel entityConditionModel) {
return new DefaultEntityQueryModel(entityConditionModel);
}
/**
* Specifies an additional condition supplier.
*/
interface AdditionalCondition extends Mutable> {
/**
* Default {@link Conjunction#AND}.
* @return the {@link Mutable} controlling the {@link Conjunction} to use when adding the additional condition
*/
Mutable conjunction();
}
}
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