mirror of https://gitee.com/bigwinds/arangodb
141 lines
3.7 KiB
Plaintext
141 lines
3.7 KiB
Plaintext
!CHAPTER Registering and Unregistering User Functions
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AQL user functions can be registered in the selected database
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using the *aqlfunctions* object as follows:
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```js
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var aqlfunctions = require("@arangodb/aql/functions");
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```
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To register a function, the fully qualified function name plus the
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function code must be specified.
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The [HTTP Interface](../HttpAqlUserFunctions/README.md) also offers User Functions management.
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!SUBSECTION Registering an AQL user function
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`aqlfunctions.register(name, code, isDeterministic)`
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Registers an AQL user function, identified by a fully qualified function
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name. The function code in *code* must be specified as a JavaScript
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function or a string representation of a JavaScript function.
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If the function code in *code* is passed as a string, it is required that
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the string evaluates to a JavaScript function definition.
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If a function identified by *name* already exists, the previous function
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definition will be updated. Please also make sure that the function code
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does not violate the [Conventions](../AqlExtending/Conventions.md) for AQL
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functions.
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The *isDeterministic* attribute can be used to specify whether the
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function results are fully deterministic (i.e. depend solely on the input
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and are the same for repeated calls with the same input values). It is not
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used at the moment but may be used for optimizations later.
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The registered function is stored in the selected database's system
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collection *_aqlfunctions*.
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The function returns *true* when it updates/replaces an existing AQL
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function of the same name, and *false* otherwise. It will throw an exception
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when it detects syntactially invalid function code.
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**Examples**
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```js
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require("@arangodb/aql/functions").register("myfunctions::temperature::celsiustofahrenheit",
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function (celsius) {
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return celsius * 1.8 + 32;
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});
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```
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The function code will not be executed in *strict mode* or *strong mode* by
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default. In order to make a user function being run in strict mode, use
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`use strict` explicitly, e.g.:
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```js
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require("@arangodb/aql/functions").register("myfunctions::temperature::celsiustofahrenheit",
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function (celsius) {
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"use strict";
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return celsius * 1.8 + 32;
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});
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```
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!SUBSECTION Deleting an existing AQL user function
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`aqlfunctions.unregister(name)`
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Unregisters an existing AQL user function, identified by the fully qualified
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function name.
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Trying to unregister a function that does not exist will result in an
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exception.
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**Examples**
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```js
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require("@arangodb/aql/functions").unregister("myfunctions::temperature::celsiustofahrenheit");
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```
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!SUBSECTION Unregister Group
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<!-- js/common/modules/@arangodb/aql/functions.js -->
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delete a group of AQL user functions
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`aqlfunctions.unregisterGroup(prefix)`
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Unregisters a group of AQL user function, identified by a common function
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group prefix.
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This will return the number of functions unregistered.
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**Examples**
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```js
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require("@arangodb/aql/functions").unregisterGroup("myfunctions::temperature");
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require("@arangodb/aql/functions").unregisterGroup("myfunctions");
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```
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!SUBSECTION Listing all AQL user functions
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`aqlfunctions.toArray()`
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Returns all previously registered AQL user functions, with their fully
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qualified names and function code.
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The result may optionally be restricted to a specified group of functions
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by specifying a group prefix:
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`aqlfunctions.toArray(prefix)`
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**Examples**
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To list all available user functions:
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```js
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require("@arangodb/aql/functions").toArray();
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```
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To list all available user functions in the *myfunctions* namespace:
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```js
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require("@arangodb/aql/functions").toArray("myfunctions");
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```
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To list all available user functions in the *myfunctions::temperature* namespace:
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```js
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require("@arangodb/aql/functions").toArray("myfunctions::temperature");
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```
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