mirror of https://gitee.com/bigwinds/arangodb
109 lines
4.3 KiB
Markdown
109 lines
4.3 KiB
Markdown
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@brief updates a document
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`collection.update(document, data, overwrite, keepNull, waitForSync)` or
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`collection.update(document, data,
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overwrite: true or false, keepNull: true or false, waitForSync: true or false)`
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Updates an existing *document*. The *document* must be a document in
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the current collection. This document is then patched with the
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*data* given as second argument. The optional *overwrite* parameter can
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be used to control the behavior in case of version conflicts (see below).
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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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The optional *waitForSync* parameter can be used to force
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synchronization of the document update operation to disk even in case
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that the *waitForSync* flag had been disabled for the entire collection.
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Thus, the *waitForSync* parameter can be used to force synchronization
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of just specific operations. To use this, set the *waitForSync* parameter
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to *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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The method returns a document with the attributes *_id*, *_rev* and
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*_oldRev*. The attribute *_id* contains the document handle of the
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updated document, the attribute *_rev* contains the document revision of
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the updated document, the attribute *_oldRev* contains the revision of
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the old (now replaced) document.
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If there is a conflict, i. e. if the revision of the *document* does not
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match the revision in the collection, then an error is thrown.
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`collection.update(document, data, true)`
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As before, but in case of a conflict, the conflict is ignored and the old
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document is overwritten.
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collection.update(document-handle, data)`
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As before. Instead of document a document-handle can be passed as
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first argument.
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*Examples*
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Create and update a document:
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@EXAMPLE_ARANGOSH_OUTPUT{documentsCollectionUpdate}
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~ db._create("example");
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a1 = db.example.insert({"a" : 1});
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a2 = db.example.update(a1, {"b" : 2, "c" : 3});
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a3 = db.example.update(a1, {"d" : 4}); // xpError(ERROR_ARANGO_CONFLICT);
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a4 = db.example.update(a2, {"e" : 5, "f" : 6 });
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db.example.document(a4);
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a5 = db.example.update(a4, {"a" : 1, c : 9, e : 42 });
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db.example.document(a5);
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~ db._drop("example");
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@END_EXAMPLE_ARANGOSH_OUTPUT
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Use a document handle:
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@EXAMPLE_ARANGOSH_OUTPUT{documentsCollectionUpdateHandle}
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~ db._create("example");
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~ var myid = db.example.insert({_key: "18612115"});
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a1 = db.example.insert({"a" : 1});
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a2 = db.example.update("example/18612115", { "x" : 1, "y" : 2 });
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~ db._drop("example");
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@END_EXAMPLE_ARANGOSH_OUTPUT
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Use the keepNull parameter to remove attributes with null values:
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@EXAMPLE_ARANGOSH_OUTPUT{documentsCollectionUpdateHandleKeepNull}
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~ db._create("example");
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~ var myid = db.example.insert({_key: "19988371"});
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db.example.insert({"a" : 1});
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|db.example.update("example/19988371",
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{ "b" : null, "c" : null, "d" : 3 });
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db.example.document("example/19988371");
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db.example.update("example/19988371", { "a" : null }, false, false);
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db.example.document("example/19988371");
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| db.example.update("example/19988371",
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{ "b" : null, "c": null, "d" : null }, false, false);
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db.example.document("example/19988371");
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~ db._drop("example");
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@END_EXAMPLE_ARANGOSH_OUTPUT
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Patching array values:
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@EXAMPLE_ARANGOSH_OUTPUT{documentsCollectionUpdateHandleArray}
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~ db._create("example");
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~ var myid = db.example.insert({_key: "20774803"});
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| db.example.insert({"a" : { "one" : 1, "two" : 2, "three" : 3 },
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"b" : { }});
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| db.example.update("example/20774803", {"a" : { "four" : 4 },
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"b" : { "b1" : 1 }});
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db.example.document("example/20774803");
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| db.example.update("example/20774803", { "a" : { "one" : null },
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| "b" : null },
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false, false);
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db.example.document("example/20774803");
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~ db._drop("example");
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@END_EXAMPLE_ARANGOSH_OUTPUT
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