arangodb/Documentation/DocuBlocks/documentsCollectionUpdateByExample.md

@brief partially updates documents matching an example collection.updateByExample(example, newValue)

Partially updates all documents matching an example with a new document body. Specific attributes in the document body of each document matching the example will be updated with the values from newValue. The document meta-attributes such as _id, _key, _from, _to cannot be updated.

Partial update could also be used to append new fields, if there were no old field with same name.

collection.updateByExample(document, newValue, keepNull, waitForSync)

The optional keepNull parameter can be used to modify the behavior when handling null values. Normally, null values are stored in the database. By setting the keepNull parameter to false, this behavior can be changed so that all attributes in data with null values will be removed from the target document.

The optional waitForSync parameter can be used to force synchronization of the document replacement operation to disk even in case that the waitForSync flag had been disabled for the entire collection. Thus, the waitForSync parameter can be used to force synchronization of just specific operations. To use this, set the waitForSync parameter to true. If the waitForSync parameter is not specified or set to false, then the collection's default waitForSync behavior is applied. The waitForSync parameter cannot be used to disable synchronization for collections that have a default waitForSync value of true.

collection.updateByExample(document, newValue, keepNull, waitForSync, limit)

The optional limit parameter can be used to restrict the number of updates to the specified value. If limit is specified but less than the number of documents in the collection, it is undefined which documents are updated.

collection.updateByExample(document, newValue, options)

Using this variant, the options for the operation can be passed using an object with the following sub-attributes:

• keepNull
• waitForSync
• limit
• mergeObjects

@EXAMPLES

@EXAMPLE_ARANGOSH_OUTPUT{012_documentsCollectionUpdateByExample} ~ db._create("example"); db.example.save({ Hello : "world", foo : "bar" }); db.example.updateByExample({ Hello: "world" }, { Hello: "foo", World: "bar" }, false); db.example.byExample({ Hello: "foo" }).toArray() ~ db._drop("example"); @END_EXAMPLE_ARANGOSH_OUTPUT