Data Validation & Quarantine
Validate incoming data with quality scoring and quarantine suspicious records without blocking the pipeline.
When to Use This Skill
- Processing external data sources that are unreliable
- Need quality scoring beyond simple schema validation
- Want to quarantine suspicious data for manual review
- Can't afford to block the pipeline for bad data
Core Concepts
External data sources are unreliable. Schema violations crash pipelines, low-quality data pollutes databases, and you can't manually review every record.
The solution:
- Validate against schema
- Score quality based on domain rules
- Pass high-quality data through
- Quarantine suspicious data for review
- Reject invalid data
┌─────────────┐ ┌───────────────┐ ┌─────────────┐
│ Raw Data │────▶│ Validator │────▶│ Valid │
└─────────────┘ └───────────────┘ └─────────────┘
│
▼
┌─────────────┐
│ Quarantine │
└─────────────┘Implementation
TypeScript
import { z, ZodError } from 'zod';
interface ValidationResult<T> {
success: boolean;
data?: T;
errors?: { path: string; message: string; code: string }[];
qualityScore: number;
warnings: string[];
}
interface BatchResult<T> {
valid: T[];
invalid: { original: unknown; errors: any[] }[];
quarantined: { original: unknown; score: number; warnings: string[] }[];
metrics: {
totalProcessed: number;
validPercent: number;
avgQualityScore: number;
processingTimeMs: number;
};
}
class DataValidator<T> {
constructor(
private schema: z.ZodSchema<T>,
private qualityScorer: (data: T) => { score: number; warnings: string[] },
private quarantineThreshold = 50
) {}
validate(raw: unknown): ValidationResult<T> {
try {
const parsed = this.schema.parse(raw);
const { score, warnings } = this.qualityScorer(parsed);
return { success: true, data: parsed, qualityScore: score, warnings };
} catch (error) {
if (error instanceof ZodError) {
return {
success: false,
errors: error.errors.map(e => ({
path: e.path.join('.'),
message: e.message,
code: e.code,
})),
qualityScore: 0,
warnings: [],
};
}
throw error;
}
}
validateBatch(items: unknown[]): BatchResult<T> {
const start = Date.now();
const valid: T[] = [];
const invalid: any[] = [];
const quarantined: any[] = [];
let totalScore = 0;
for (const item of items) {
const result = this.validate(item);
if (!result.success) {
invalid.push({ original: item, errors: result.errors });
} else if (result.qualityScore < this.quarantineThreshold) {
quarantined.push({
original: item,
score: result.qualityScore,
warnings: result.warnings,
});
} else {
valid.push(result.data!);
totalScore += result.qualityScore;
}
}
return {
valid,
invalid,
quarantined,
metrics: {
totalProcessed: items.length,
validPercent: items.length > 0 ? (valid.length / items.length) * 100 : 0,
avgQualityScore: valid.length > 0 ? totalScore / valid.length : 0,
processingTimeMs: Date.now() - start,
},
};
}
}
// ============================================
// Quality Scorer Example
// ============================================
interface Article {
title: string;
url: string;
domain: string;
publishedAt: string;
}
function scoreArticle(article: Article): { score: number; warnings: string[] } {
let score = 100;
const warnings: string[] = [];
// Title checks
if (article.title.length < 20) {
score -= 10;
warnings.push('Short title');
}
if (/\b(click|subscribe|newsletter)\b/i.test(article.title)) {
score -= 15;
warnings.push('Promotional language');
}
// Source checks
const ugcPlatforms = ['blogspot', 'wordpress', 'medium'];
if (ugcPlatforms.some(p => article.domain.includes(p))) {
score -= 10;
warnings.push('User-generated content platform');
}
// Freshness check
const ageMs = Date.now() - new Date(article.publishedAt).getTime();
if (ageMs > 365 * 24 * 60 * 60 * 1000) {
score -= 20;
warnings.push('Article over 1 year old');
}
return { score: Math.max(0, score), warnings };
}
// ============================================
// Quarantine Store
// ============================================
type QuarantineReason =
| 'low_quality_score'
| 'suspicious_content'
| 'duplicate_detected'
| 'source_blacklisted';
interface QuarantinedItem<T> {
id: string;
data: T;
reason: QuarantineReason;
qualityScore: number;
warnings: string[];
quarantinedAt: string;
reviewStatus: 'pending' | 'approved' | 'rejected';
}
class QuarantineStore<T> {
private items = new Map<string, QuarantinedItem<T>>();
private maxItems = 10000;
private autoRejectDays = 7;
add(
data: T,
reason: QuarantineReason,
score: number,
warnings: string[]
): string {
const id = `q_${Date.now()}_${Math.random().toString(36).slice(2, 8)}`;
this.items.set(id, {
id,
data,
reason,
qualityScore: score,
warnings,
quarantinedAt: new Date().toISOString(),
reviewStatus: 'pending',
});
this.enforceLimit();
return id;
}
approve(id: string): T | null {
const item = this.items.get(id);
if (!item || item.reviewStatus !== 'pending') return null;
item.reviewStatus = 'approved';
return item.data;
}
reject(id: string): boolean {
const item = this.items.get(id);
if (!item) return false;
item.reviewStatus = 'rejected';
return true;
}
getPending(limit = 100): QuarantinedItem<T>[] {
return Array.from(this.items.values())
.filter(i => i.reviewStatus === 'pending')
.slice(0, limit);
}
releaseApproved(): T[] {
const approved: T[] = [];
for (const [id, item] of this.items) {
if (item.reviewStatus === 'approved') {
approved.push(item.data);
this.items.delete(id);
}
}
return approved;
}
autoRejectStale(): number {
const cutoff = Date.now() - this.autoRejectDays * 24 * 60 * 60 * 1000;
let count = 0;
for (const item of this.items.values()) {
if (item.reviewStatus === 'pending' &&
new Date(item.quarantinedAt).getTime() < cutoff) {
item.reviewStatus = 'rejected';
count++;
}
}
return count;
}
private enforceLimit(): void {
if (this.items.size <= this.maxItems) return;
const sorted = Array.from(this.items.entries())
.sort((a, b) => {
if (a[1].reviewStatus === 'rejected' && b[1].reviewStatus !== 'rejected') return -1;
return new Date(a[1].quarantinedAt).getTime() - new Date(b[1].quarantinedAt).getTime();
});
while (sorted.length > this.maxItems) {
const [id] = sorted.shift()!;
this.items.delete(id);
}
}
}Usage Examples
Basic Validation Pipeline
const ArticleSchema = z.object({
title: z.string().min(1),
url: z.string().url(),
domain: z.string(),
publishedAt: z.string().datetime(),
});
type Article = z.infer<typeof ArticleSchema>;
const validator = new DataValidator(ArticleSchema, scoreArticle, 50);
const quarantine = new QuarantineStore<Article>();
// Process batch
const result = validator.validateBatch(rawArticles);
// Handle quarantined items
for (const q of result.quarantined) {
quarantine.add(q.original as Article, 'low_quality_score', q.score, q.warnings);
}
// Use valid data
await saveToDatabase(result.valid);
console.log(`Processed: ${result.metrics.totalProcessed}`);
console.log(`Valid: ${result.valid.length} (${result.metrics.validPercent.toFixed(1)}%)`);
console.log(`Quarantined: ${result.quarantined.length}`);Best Practices
- Never block the pipeline for bad data - quarantine instead
- Quality scores are domain-specific - tune thresholds based on your data
- Auto-reject stale quarantined items - don't let the queue grow forever
- Expose quarantine for manual review via admin UI
- Track metrics to identify data quality trends
Common Mistakes
- Blocking the entire pipeline when validation fails
- Using only schema validation without quality scoring
- Not setting limits on quarantine store size
- Forgetting to auto-reject stale items
- Not exposing quarantine for manual review
Related Patterns
- batch-processing - Process validated items efficiently
- deduplication - Deduplicate before validation
- error-sanitization - Sanitize validation error messages