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Add Datastore retrieving query samples. #204

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Apr 27, 2016
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Add Datastore retrieving query samples. #204

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82 changes: 82 additions & 0 deletions appengine/datastore/src/test/java/com/example/appengine/QueriesTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -17,13 +17,15 @@
package com.example.appengine;

import static com.google.common.truth.Truth.assertThat;
import static org.junit.Assert.fail;

import com.google.appengine.api.datastore.DatastoreService;
import com.google.appengine.api.datastore.DatastoreServiceFactory;
import com.google.appengine.api.datastore.Entity;
import com.google.appengine.api.datastore.FetchOptions;
import com.google.appengine.api.datastore.Key;
import com.google.appengine.api.datastore.PreparedQuery;
import com.google.appengine.api.datastore.PreparedQuery.TooManyResultsException;
import com.google.appengine.api.datastore.Query;
import com.google.appengine.api.datastore.Query.CompositeFilter;
import com.google.appengine.api.datastore.Query.CompositeFilterOperator;
Expand Down Expand Up @@ -781,6 +783,86 @@ public void queryRestrictions_surprisingMultipleValuesTwoNotEquals_returnsMatche
// Datastore.
}

private Entity retrievePersonWithLastName(String targetLastName) {
// [START single_retrieval_example]
Query q =
new Query("Person")
.setFilter(new FilterPredicate("lastName", FilterOperator.EQUAL, targetLastName));

PreparedQuery pq = datastore.prepare(q);
Entity result = pq.asSingleEntity();
// [END single_retrieval_example]
return result;
}

@Test
public void singleRetrievalExample_singleEntity_returnsEntity() throws Exception {
Entity a = new Entity("Person", "a");
a.setProperty("lastName", "Johnson");
Entity b = new Entity("Person", "b");
b.setProperty("lastName", "Smith");
datastore.put(ImmutableList.<Entity>of(a, b));

Entity result = retrievePersonWithLastName("Johnson");

assertThat(result.getKey()).named("result key").isEqualTo(a.getKey());
}

@Test
public void singleRetrievalExample_multitpleEntities_throwsException() throws Exception {
Entity a = new Entity("Person", "a");
a.setProperty("lastName", "Johnson");
Entity b = new Entity("Person", "b");
b.setProperty("lastName", "Johnson");
datastore.put(ImmutableList.<Entity>of(a, b));

try {
Entity result = retrievePersonWithLastName("Johnson");
fail("Expected TooManyResultsException");
} catch (TooManyResultsException expected) {
// TooManyResultsException does not provide addition details.
}
}

// [START query_limit_example]
private List<Entity> getTallestPeople() {
DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();

Query q = new Query("Person").addSort("height", SortDirection.DESCENDING);

PreparedQuery pq = datastore.prepare(q);
return pq.asList(FetchOptions.Builder.withLimit(5));
}
// [END query_limit_example]

@Test
public void queryLimitExample_returnsLimitedEntities() throws Exception {
Entity a = new Entity("Person", "a");
a.setProperty("height", 200);
Entity b = new Entity("Person", "b");
b.setProperty("height", 199);
Entity c = new Entity("Person", "c");
c.setProperty("height", 201);
Entity d = new Entity("Person", "d");
d.setProperty("height", 198);
Entity e = new Entity("Person", "e");
e.setProperty("height", 202);
Entity f = new Entity("Person", "f");
f.setProperty("height", 197);
Entity g = new Entity("Person", "g");
g.setProperty("height", 203);
Entity h = new Entity("Person", "h");
h.setProperty("height", 196);
datastore.put(ImmutableList.<Entity>of(a, b, c, d, e, f, g, h));

List<Entity> results = getTallestPeople();

assertThat(getKeys(results))
.named("result keys")
.containsExactly(g.getKey(), e.getKey(), c.getKey(), a.getKey(), b.getKey())
.inOrder();
}

private ImmutableList<Key> getKeys(List<Entity> entities) {
ImmutableList.Builder<Key> keys = ImmutableList.builder();
for (Entity entity : entities) {
Expand Down