Mongodb Data Practices

MongoDB Data Practices

Application skill for jsoendermann MongoStyleGuide + MongoDB official data-modeling ingest (awesome-guidelines). Application-layer JS/Node: also node-coding-practices / javascript-coding-practices.

Core Principle

Mongo schema quality is self-documenting BSON aligned to read patterns, explicit enum states, consistent null semantics, camelCase keys, and embed/reference choices driven by access patterns not premature scale fantasies.

When to Use / NOT

• Designing new collections, migrations, $jsonSchema validators.
• Reviewing BSON documents, seed data, aggregation inputs.
• Choosing embed vs reference for related entities.

NOT when:

• SQL relational schemas, sql-scripting-practices.
• MongoDB server C++ contributions, upstream server styleguides.
• Generic API JSON without Mongo persistence, json-api-practices.

Workflow

1. Enums/booleans, UPPERCASE strings, prefixes, merge flags (mongo-style-enums-booleans.md).
2. Dates/null/types, Date vs day string, homogeneous columns (mongo-style-dates-null-types.md).
3. Names/IDs, camelCase, collections, string _id (mongo-style-names-ids.md).
4. Modeling, nesting, embed/reference, validation, indexes (mongo-style-modelling-verify.md).
5. Verify, $jsonSchema, index explain, sample doc audit.

Red Flags

• Numeric or boolean enum codes
• null / missing as enum "unknown"
• Title-case enum mixed with UPPERCASE constants
• Mutually exclusive boolean triplets
• ISO date strings persisted instead of BSON Date
• Date type for birthdate-only fields
• Business meaning overloaded onto null/undefined
• null and missing mixed in same field path
• null instead of '' or [] defaults
• Mixed BSON types in one field
• Heterogeneous object shapes in array columns
• 0 or '' as "unknown" sentinel
• Numeric strings for arithmetic fields
• ObjectId _id with app serialization bugs
• snake_case field keys in JS-first apps
• Unbounded embedded arrays without reference split
• Deep nesting without subdocument justification
• Transactions compensating for bad embed choice
• Hot queries without supporting indexes
• Abbreviated field names outside domain DSL

Verification

• $jsonSchema or validator on changed collections
• $type / sample audit on enum and date fields
• Embed/reference checklist vs MongoDB official table
• explain() on primary read paths; index list matches filters/sorts
• Capsule probes cited in review notes

References

• awesome-guidelines/references/mongo-style-learning-note.md
• awesome-guidelines/references/mongo-style-enums-booleans.md
• awesome-guidelines/references/mongo-style-dates-null-types.md
• awesome-guidelines/references/mongo-style-names-ids.md
• awesome-guidelines/references/mongo-style-modelling-verify.md

Related skills

• node-coding-practices, Node app code reading/writing documents
• javascript-coding-practices, app-layer validation and types
• sql-scripting-practices, when data lives in SQL instead