MongoPatchGenerator

MongoPatchGenerator converts an OPRA patch DTO into a MongoDB update filter ($set, $unset, $push, $pull). It is used internally by MongoEntityService to translate MongoPatchDTO<T> objects, but can be used directly when you need to build a custom update pipeline.

import { MongoPatchGenerator } from '@opra/mongodb';

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Constructor

new MongoPatchGenerator()

No constructor arguments.

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Methods

generatePatch

generatePatch<T extends object>(
  dataType: ComplexType,
  doc: PatchDTO<T>,
  options?: MongoPatchGenerator.Options,
): {
  update: UpdateFilter<T>;
  arrayFilters?: Record<string, any>[];
  initArrayFields?: string[];
}

Generates a MongoDB update filter from an OPRA patch document.

Parameters

Parameter	Type	Description
dataType	ComplexType	The OPRA ComplexType that describes the document schema
doc	PatchDTO<T>	The patch object. Nested fields, array push/pull (_$push, _$pull), and null (unset) values are all supported.
options	MongoPatchGenerator.Options	See Interfaces below

Returns

Property	Type	Description
update	UpdateFilter<T>	The MongoDB update filter ($set, $unset, $push, $pull)
arrayFilters	Record<string, any>[]	Array filters needed for nested entity updates — pass as the arrayFilters option to MongoDB
initArrayFields	string[]	Fields that must be initialized as empty arrays before the update is applied

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Patch object conventions

Value	Behaviour
null for a field	Field is added to $unset
Non-null scalar	Field is added to $set
Nested object for a ComplexType field	Recursively processed — only changed sub-fields are set
_$push: { fieldName: value }	Appends to an array field using $push
_$pull: { fieldName: [values] }	Removes matching items from an array using $pull

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Interfaces

MongoPatchGenerator.Options

Option	Type	Description
currentPath	string	Dot-notation path prefix to prepend to all generated field paths (useful for nested service patches)
scope	string	Schema scope to apply when resolving fields from the data type