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rx-java Observables for jdbc
package com.github.davidmoten.rx.jdbc;
import static com.github.davidmoten.rx.jdbc.Conditions.checkNotNull;
import static com.github.davidmoten.rx.jdbc.Queries.bufferedParameters;
import java.util.List;
import rx.Observable;
import rx.Observable.Operator;
import rx.functions.Func1;
/**
* Always emits an Observable of size 1 containing the number of
* affected records.
*/
final public class QueryUpdate implements Query {
private final String sql;
private final Observable parameters;
private final QueryContext context;
private final Observable depends;
/**
* Private constructor.
*
* @param sql
* @param parameters
* @param depends
* @param context
*/
private QueryUpdate(String sql, Observable parameters, Observable depends,
QueryContext context) {
checkNotNull(sql);
checkNotNull(parameters);
checkNotNull(depends);
checkNotNull(context);
this.sql = sql;
this.parameters = parameters;
this.depends = depends;
this.context = context;
}
@Override
public String sql() {
return sql;
}
@Override
public Observable parameters() {
return parameters;
}
@Override
public QueryContext context() {
return context;
}
@Override
public String toString() {
return "QueryUpdate [sql=" + sql + "]";
}
@Override
public Observable depends() {
return depends;
}
/**
* Returns the results of an update query. Should be an {@link Observable}
* of size 1 containing the number of records affected by the update (or
* insert) statement.
*
* @param query
* @return
*/
public Observable count() {
return bufferedParameters(this)
// execute query for each set of parameters
.concatMap(executeOnce());
}
/**
* Returns a {@link Func1} that itself returns the results of pushing
* parameters through an update query.
*
* @param query
* @return
*/
private Func1, Observable> executeOnce() {
return new Func1, Observable>() {
@Override
public Observable call(final List params) {
if (sql.equals(QueryUpdateOperation.BEGIN_TRANSACTION)) {
context.beginTransactionSubscribe();
}
Observable result = executeOnce(params).subscribeOn(context.scheduler());
if (sql.equals(QueryUpdateOperation.COMMIT)
|| sql.equals(QueryUpdateOperation.ROLLBACK))
context.endTransactionSubscribe();
return result;
}
};
}
/**
* Returns the results of an update query. Should return an
* {@link Observable} of size one containing the rows affected count.
*
* @param query
* @param parameters
* @return
*/
private Observable executeOnce(final List parameters) {
return QueryUpdateOperation.execute(this, parameters);
}
/**
* Builds a {@link QueryUpdate}.
*/
final public static class Builder {
/**
* Standard query builder.
*/
private final QueryBuilder builder;
/**
* Constructor.
*
* @param sql
* @param db
*/
public Builder(String sql, Database db) {
this.builder = new QueryBuilder(sql, db);
}
/**
* Appends the given parameters to the parameter list for the query. If
* there are more parameters than required for one execution of the
* query then more than one execution of the query will occur.
*
* @param parameters
* @return this
*/
public Builder parameters(Observable parameters) {
builder.parameters(parameters);
return this;
}
/**
* Appends the given parameter values to the parameter list for the
* query. If there are more parameters than required for one execution
* of the query then more than one execution of the query will occur.
*
* @param objects
* @return this
*/
public Builder parameters(Object... objects) {
builder.parameters(objects);
return this;
}
/**
* Appends a parameter to the parameter list for the query. If there are
* more parameters than required for one execution of the query then
* more than one execution of the query will occur.
*
* @param value
* @return this
*/
public Builder parameter(Object value) {
builder.parameter(value);
return this;
}
/**
* Appends a parameter to the parameter list for the query for a CLOB
* parameter and handles null appropriately. If there are more
* parameters than required for one execution of the query then more
* than one execution of the query will occur.
*
* @param value
* the string to insert in the CLOB column
* @return this
*/
public Builder parameterClob(String value) {
builder.parameter(Database.toSentinelIfNull(value));
return this;
}
/**
* Appends a parameter to the parameter list for the query for a CLOB
* parameter and handles null appropriately. If there are more
* parameters than required for one execution of the query then more
* than one execution of the query will occur.
*
* @param value
* @return this
*/
public Builder parameterBlob(byte[] bytes) {
builder.parameter(Database.toSentinelIfNull(bytes));
return this;
}
/**
* Appends a dependency to the dependencies that have to complete their
* emitting before the query is executed.
*
* @param dependency
* @return this
*/
public Builder dependsOn(Observable dependency) {
builder.dependsOn(dependency);
return this;
}
/**
* Appends a dependency on the result of the last transaction (
* true for commit or false for rollback) to
* the dependencies that have to complete their emitting before the
* query is executed.
*
* @return this
*/
public Builder dependsOnLastTransaction() {
builder.dependsOnLastTransaction();
return this;
}
/**
* Returns an {@link Observable} with the count of rows affected by the
* update statement.
*
* @return
*/
public Observable count() {
return new QueryUpdate(builder.sql(), builder.parameters(), builder.depends(),
builder.context()).count();
}
/**
* Returns an {@link Operator} to allow the query to be pushed
* parameters via the {@link Observable#lift(Operator)} method.
*
* @return operator that acts on parameters
*/
public Operator parameterOperator() {
return new QueryUpdateOperator © 2015 - 2025 Weber Informatics LLC | Privacy Policy