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jstewart148
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jyemin
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Add getEmbedded methods for extracting values in embedded documents
JAVA-2532
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‎bson/src/main/org/bson/Document.java‎

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Original file line numberDiff line numberDiff line change
@@ -32,12 +32,14 @@
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import java.io.StringWriter;
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import java.util.Collection;
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import java.util.Date;
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import java.util.Iterator;
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import java.util.LinkedHashMap;
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import java.util.List;
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import java.util.Map;
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import java.util.Set;
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import static java.lang.String.format;
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import static org.bson.assertions.Assertions.isTrue;
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import static org.bson.assertions.Assertions.notNull;
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/**
@@ -160,6 +162,76 @@ public <T> T get(final Object key, final T defaultValue) {
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return value == null ? defaultValue : (T) value;
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}
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/**
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* Gets the value in an embedded document, casting it to the given {@code Class<T>}. The list of keys represents a path to the
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* embedded value, drilling down into an embedded document for each key. This is useful to avoid having casts in
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* client code, though the effect is the same.
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*
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* The generic type of the keys list is {@code ?} to be consistent with the corresponding {@code get} methods, but in practice
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* the actual type of the argument should be {@code List<String>}. So to get the embedded value of a key list that is of type String,
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* you would write {@code String name = doc.getEmbedded(List.of("employee", "manager", "name"), String.class)} instead of
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* {@code String name = (String) doc.get("employee", Document.class).get("manager", Document.class).get("name") }.
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*
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* @param keys the list of keys
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* @param clazz the non-null class to cast the value to
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* @param <T> the type of the class
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* @return the value of the given embedded key, or null if the instance does not contain this embedded key.
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* @throws ClassCastException if the value of the given embedded key is not of type T
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* @since 3.10
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*/
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public <T> T getEmbedded(final List<?> keys, final Class<T> clazz) {
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notNull("keys", keys);
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isTrue("keys", !keys.isEmpty());
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notNull("clazz", clazz);
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return getEmbeddedValue(keys, clazz, null);
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}
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/**
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* Gets the value in an embedded document, casting it to the given {@code Class<T>} or returning the default value if null.
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* The list of keys represents a path to the embedded value, drilling down into an embedded document for each key.
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* This is useful to avoid having casts in client code, though the effect is the same.
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*
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* The generic type of the keys list is {@code ?} to be consistent with the corresponding {@code get} methods, but in practice
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* the actual type of the argument should be {@code List<String>}. So to get the embedded value of a key list that is of type String,
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* you would write {@code String name = doc.getEmbedded(List.of("employee", "manager", "name"), "John Smith")} instead of
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* {@code String name = doc.get("employee", Document.class).get("manager", Document.class).get("name", "John Smith") }.
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*
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* @param keys the list of keys
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* @param defaultValue what to return if the value is null
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* @param <T> the type of the class
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* @return the value of the given key, or null if the instance does not contain this key.
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* @throws ClassCastException if the value of the given key is not of type T
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* @since 3.10
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*/
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public <T> T getEmbedded(final List<?> keys, final T defaultValue) {
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notNull("keys", keys);
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isTrue("keys", !keys.isEmpty());
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notNull("defaultValue", defaultValue);
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return getEmbeddedValue(keys, null, defaultValue);
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}
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// Gets the embedded value of the given list of keys, casting it to {@code Class<T>} or returning the default value if null.
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// Throws ClassCastException if any of the intermediate embedded values is not a Document.
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@SuppressWarnings("unchecked")
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private <T> T getEmbeddedValue(final List<?> keys, final Class<T> clazz, final T defaultValue) {
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Object value = this;
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Iterator<?> keyIterator = keys.iterator();
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while (keyIterator.hasNext()) {
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Object key = keyIterator.next();
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value = ((Document) value).get(key);
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if (!(value instanceof Document)) {
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if (value == null) {
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return defaultValue;
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} else if (keyIterator.hasNext()) {
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throw new ClassCastException(format("At key %s, the value is not a Document (%s)",
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key, value.getClass().getName()));
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}
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}
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}
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return clazz != null ? clazz.cast(value) : (T) value;
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}
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/**
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* Gets the value of the given key as an Integer.
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*

‎bson/src/test/unit/org/bson/types/DocumentSpecification.groovy‎

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Original file line numberDiff line numberDiff line change
@@ -126,6 +126,102 @@ class DocumentSpecification extends Specification {
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thrown(ClassCastException)
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}
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def 'should return null when getting embedded value'() {
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when:
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Document document = Document.parse("{a: 1, b: {x: [2, 3, 4], y: {m: 'one', len: 3}}, 'a.b': 'two'}")
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then:
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document.getEmbedded(List.of('notAKey'), String) == null
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document.getEmbedded(List.of('b', 'y', 'notAKey'), String) == null
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document.getEmbedded(List.of('b', 'b', 'm'), String) == null
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Document.parse('{}').getEmbedded(List.of('a', 'b'), Integer) == null
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Document.parse('{b: 1}').getEmbedded(['a'], Integer) == null
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Document.parse('{b: 1}').getEmbedded(['a', 'b'], Integer) == null
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Document.parse('{a: {c: 1}}').getEmbedded(['a', 'b'], Integer) == null
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Document.parse('{a: {c: 1}}').getEmbedded(['a', 'b', 'c'], Integer) == null
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}
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def 'should return embedded value'() {
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given:
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Date date = new Date();
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ObjectId objectId = new ObjectId();
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when:
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Document document = Document.parse("{a: 1, b: {x: [2, 3, 4], y: {m: 'one', len: 3}}, 'a.b': 'two'}")
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.append('l', new Document('long', 2L))
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.append('d', new Document('double', 3.0 as double))
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.append('t', new Document('boolean', true))
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.append('o', new Document('objectId', objectId))
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.append('n', new Document('date', date))
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then:
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document.getEmbedded(List.of('a'), Integer) == 1
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document.getEmbedded(List.of('b', 'x'), List).get(0) == 2
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document.getEmbedded(List.of('b', 'x'), List).get(1) == 3
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document.getEmbedded(List.of('b', 'x'), List).get(2) == 4
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document.getEmbedded(List.of('b', 'y', 'm'), String) == 'one'
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document.getEmbedded(List.of('b', 'y', 'len'), Integer) == 3
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document.getEmbedded(List.of('a.b'), String) == 'two'
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document.getEmbedded(List.of('b', 'y'), Document).getString('m') == 'one'
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document.getEmbedded(List.of('b', 'y'), Document).getInteger('len') == 3
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document.getEmbedded(Arrays.asList('l', 'long'), Long) == 2L
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document.getEmbedded(Arrays.asList('d', 'double'), Double) == 3.0d
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document.getEmbedded(Arrays.asList('l', 'long'), Number) == 2L
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document.getEmbedded(Arrays.asList('d', 'double'), Number) == 3.0d
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document.getEmbedded(Arrays.asList('t', 'boolean'), Boolean) == true
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document.getEmbedded(Arrays.asList('t', 'x'), false) == false
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document.getEmbedded(Arrays.asList('o', 'objectId'), ObjectId) == objectId
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document.getEmbedded(Arrays.asList('n', 'date'), Date) == date
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}
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def 'should throw an exception getting an embedded value'() {
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given:
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Document document = Document.parse("{a: 1, b: {x: [2, 3, 4], y: {m: 'one', len: 3}}, 'a.b': 'two'}")
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when:
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document.getEmbedded(null, String) == null
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then:
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thrown(IllegalArgumentException)
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when:
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document.getEmbedded(List.of(), String) == null
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then:
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thrown(IllegalStateException)
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when:
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document.getEmbedded(['a', 'b'], Integer)
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then:
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thrown(ClassCastException)
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when:
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document.getEmbedded(List.of('b', 'y', 'm'), Integer)
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then:
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thrown(ClassCastException)
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when:
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document.getEmbedded(List.of('b', 'x'), Document)
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then:
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thrown(ClassCastException)
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when:
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document.getEmbedded(List.of('b', 'x', 'm'), String)
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then:
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thrown(ClassCastException)
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when:
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document.getEmbedded(Arrays.asList('b', 'x', 'm'), 'invalid')
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then:
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thrown(ClassCastException)
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}
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def 'should parse a valid JSON string to a Document'() {
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when:
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Document document = Document.parse("{ 'int' : 1, 'string' : 'abc' }");

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