Use an uncovered aggregation stage
A required MongoDB aggregation stage has no corresponding typed pipeline method.
Prisma · Pipe
take
pipe(stage) appends a manually constructed MongoDB pipeline stage when typed pipeline methods do not cover an operation. The existing row type is retained.
How it works
The pipe(stage) helper appends a manually constructed MongoDB stage to a pipeline. It preserves the row type already established by the pipeline, while allowing stages represented by the Mongo*Stage classes to be used directly.
Syntax
pipe(stage)Parameters
| Name | Type | Description |
|---|---|---|
stage | Mongo*Stage | A constructed raw MongoDB pipeline stage, typically one of the exported Mongo*Stage classes. |
Returns
A pipeline with the raw stage appended and the existing row type preserved.
Key points
- Pass a constructed stage to
pipe(stage)to add it to the current pipeline. - Raw pipeline stages use the exported MongoDB stage-class family.
- The execution module provides a separate stage class for each MongoDB stage.
- Import the raw stage classes from the documented execution module.
- Derive a stage class name by wrapping the MongoDB stage name with the
Mongoprefix andStagesuffix. - The
$unwindMongoDB stage is represented byMongoUnwindStage.
Common mistakes
- Use pipe only when the typed pipeline methods do not provide the required MongoDB operation.
- Adding a raw stage does not change the pipeline's existing row type.
Example: Append raw MongoDB stages
import { PrismaClient } from '@prisma/client'
import { MongoMatchStage, MongoCountStage, MongoFieldFilter } from '@prisma/orm-mongo/query-ast/execution'
const prisma = new PrismaClient()
const result = await prisma.user
.aggregate()
.pipe(new MongoMatchStage(new MongoFieldFilter('active', true)))
.pipe(new MongoCountStage('total'))
.run()Adds raw MongoDB pipeline stages when the typed pipeline methods do not cover the required operation.
When to use it
Add a raw match stage
A pipeline needs a manually constructed match stage with a field filter.
Compose MongoDB stage classes
A pipeline needs a count or unwind stage represented by an execution-layer class.
Interview questions
QWhat does the pipe helper do?
pipe(stage) appends a raw MongoDB pipeline stage that you construct yourself. It is intended for operations not covered by the pipeline builder's typed methods.
Follow-up: How are raw stages represented? They are instances of MongoDB stage classes exported from @prisma/orm-mongo/query-ast/execution.
QWhat happens to the row type after calling pipe?
The helper preserves the row type already present in the pipeline. This lets a custom stage extend the pipeline without replacing its established type information.
Follow-up: Why does that matter? Subsequent pipeline operations can continue to use the known result shape for type checking.
QHow do you identify the class for a MongoDB stage?
Stage classes follow a naming convention: Mongo, then the MongoDB stage name without its dollar sign, then Stage. For example, $unwind maps to MongoUnwindStage.
Follow-up: Which supporting helper is documented? MongoFieldFilter builds the filter accepted by a MongoMatchStage.
Related
pipe()Mongo*StageMongoUnwindStageMongoMatchStageMongoCountStageMongoFieldFilter