mirror of https://gitee.com/bigwinds/arangodb
60 lines
2.8 KiB
Markdown
60 lines
2.8 KiB
Markdown
////////////////////////////////////////////////////////////////////////////////
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/// @startDocuBlock documentsCollectionUpdateByExample
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/// @brief partially updates documents matching an example
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/// `collection.updateByExample(example, newValue)`
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///
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/// Partially updates all documents matching an example with a new document body.
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/// Specific attributes in the document body of each document matching the
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/// *example* will be updated with the values from *newValue*.
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/// The document meta-attributes such as *_id*, *_key*, *_from*,
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/// *_to* cannot be updated.
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///
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/// Partial update could also be used to append new fields,
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/// if there were no old field with same name.
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///
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/// `collection.updateByExample(document, newValue, keepNull, waitForSync)`
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///
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/// The optional *keepNull* parameter can be used to modify the behavior when
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/// handling *null* values. Normally, *null* values are stored in the
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/// database. By setting the *keepNull* parameter to *false*, this behavior
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/// can be changed so that all attributes in *data* with *null* values will
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/// be removed from the target document.
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///
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/// The optional *waitForSync* parameter can be used to force synchronization
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/// of the document replacement operation to disk even in case that the
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/// *waitForSync* flag had been disabled for the entire collection. Thus,
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/// the *waitForSync* parameter can be used to force synchronization of just
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/// specific operations. To use this, set the *waitForSync* parameter to
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/// *true*. If the *waitForSync* parameter is not specified or set to
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/// *false*, then the collection's default *waitForSync* behavior is
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/// applied. The *waitForSync* parameter cannot be used to disable
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/// synchronization for collections that have a default *waitForSync* value
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/// of *true*.
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///
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/// `collection.updateByExample(document, newValue, keepNull, waitForSync, limit)`
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///
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/// The optional *limit* parameter can be used to restrict the number of
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/// updates to the specified value. If *limit* is specified but less than
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/// the number of documents in the collection, it is undefined which documents are
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/// updated.
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///
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/// `collection.updateByExample(document, newValue, options)`
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///
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/// Using this variant, the options for the operation can be passed using
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/// an object with the following sub-attributes:
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/// - *keepNull*
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/// - *waitForSync*
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/// - *limit*
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/// - *mergeObjects*
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///
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/// @EXAMPLES
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///
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/// @EXAMPLE_ARANGOSH_OUTPUT{012_documentsCollectionUpdateByExample}
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/// ~ db._create("example");
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/// db.example.save({ Hello : "world", foo : "bar" });
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/// db.example.updateByExample({ Hello: "world" }, { Hello: "foo", World: "bar" }, false);
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/// db.example.byExample({ Hello: "foo" }).toArray()
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/// ~ db._drop("example");
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/// @END_EXAMPLE_ARANGOSH_OUTPUT
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/// @endDocuBlock
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//////////////////////////////////////////////////////////////////////////////// |