Prisma Filtering & where Design Translate only approved public filters into Prisma query objects
Phase 15 - Filtering, Search, Sorting & Pagination Volume 04 - Professional Backend
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Phase 15 turns an unbounded collection endpoint into a validated, queryable, stable, paginated API contract.
Build Prisma where from validated filters After validation, each optional filter can be translated into a Prisma TaskWhereInput. The service should build this intentionally instead of forwarding the entire query object to Prisma.
private buildWhere(query: TaskListQueryDto): Prisma.TaskWhereInput { return { ...(query.projectId ? { projectId: query.projectId } : {}), ...(query.assigneeId ? { assigneeId: query.assigneeId } : {}), ...(query.status ? { status: query.status } : {}), ...(query.priority ? { priority: query.priority } : {}), }; }
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buildWhere()
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The transport contract is translated into persistence-specific query input inside the service layer.
AND is the natural default The example means projectId + status + priority filters all apply together. That is usually what users expect when they add several table filters: narrow the result set by all selected criteria.
Relation filters remain possible Prisma supports relation filters, but do not expose every relational capability as a public query parameter. Add only filters the product genuinely needs, document them, validate them, then index the resulting workload if measurements justify it.
TaskListQueryDto is our public HTTP contract. Prisma.TaskWhereInput is an internal persistence shape. Keeping the translation explicit prevents clients from gaining accidental access to arbitrary database query capability.
Authentication answers who the request represents. Treating decoded or client-supplied identity as trusted is a security boundary failure.
Restate the goal of “Prisma Filtering and Where Design” as one observable behavior. Write the success signal before touching code.
Trace the boundary map: credentials/session → token → verification → trusted identity → protected operation. Mark the one boundary this lesson changes.
Inspect the current repository state and record the exact files, route, table, or runtime involved. Avoid creating an abstraction before you can name the existing owner.
Implement the smallest vertical slice. Add one coherent change, run the narrowest verification command, and read the output before continuing.
Connect the slice to TaskFlow’s phase artifact: Task list API with filter/search/sort/page contract plus metadata and indexes justified by measured query patterns.. Verify behavior from the outside as a user or API client would.
Create one controlled failure that is safe to reproduce. Predict the symptom first, capture evidence, locate the earliest broken boundary, then fix only that cause.
Close the reference and rebuild or explain the core change from memory. Record what you would monitor or test before trusting the same change in production.
const token = readBearerToken(request);
const claims = await verifier.verify(token);
request.user = {
id: claims.sub,
email: claims.email,
};Do not copy this as a finished answer. Predict what each boundary does, type the smallest useful slice, run it, then compare the result with your prediction.
Inspect whether a token exists, whether it is expired, which issuer/audience signed it, and what the API verifier expects.
Trust only verified server claims; never repair identity by accepting a client-sent user id.
Without copying the final source, create a second small scenario that applies “Prisma Filtering and Where Design” to a different TaskFlow resource or input. Write the acceptance criteria first, implement it, and provide the evidence that each criterion is satisfied.
Implement filters and text search with clearly defined case/field semantics.
Use the smallest change that demonstrates this lesson. Stop after it works and capture evidence.Client sends database column names unchecked
Predict the symptom before causing the failure. Then locate the earliest boundary where reality diverges from expectation.Why does this responsibility live here, what input does it trust, what output proves success, and what would go wrong if another layer owned it?
If your explanation is vague, repeat the boundary trace before moving on.Close the reference. Reproduce the core idea from memory or explain the exact request/data flow aloud. Then check your diff or notes for accidental shortcuts that bypass validation, authorization, error handling, or verification earned in earlier phases.