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Simfinity.js can generate a GraphQL API and PostgreSQL storage descriptions from GraphQL.js object types and relation metadata. The workflow is: define and register types, build the schema, initialize the PostgreSQL adapter, then serve the schema. The adapter does not replace your database operations, migration plan, authentication, or application-specific access rules.
What Simfinity.js generates from GraphQL types
A GraphQLObjectType is the starting point for both the API and generated storage. After you register the types and call createSchema(), Simfinity prepares the generated inputs, queries, mutations, resolvers, and storage descriptions. Which types receive root CRUD operations depends on how you register them. Simfinity.js schema definition
The generated GraphQL operation names and input shapes are intended to be shared across database adapters for the same type registrations and relation metadata. The underlying persistence is not shared: PostgreSQL uses SQL tables and constraints, while the MongoDB adapter uses Mongoose and MongoDB storage. Simfinity.js database comparison
How to define and register your types
1. Define the domain object types
Use GraphQL.js types to describe the public fields: scalars, enums, lists, and related object types. Descriptions document the API; extension metadata can describe relations or behavior used by Simfinity. The relationship metadata matters because it informs both generated resolvers and PostgreSQL storage. Schema definition guide
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2. Register endpoint and supporting types
Call connect() for a type that should have its own root operations. Register supporting types with addNoEndpointType() when they are needed by other types but should not receive their own CRUD endpoints. Register every type before calling createSchema(). Schema definition guide
3. Build the executable schema
Call createSchema() after registration. Simfinity prepares the generated API surface, including inputs, list and detail operations, mutations, and relation resolvers. Decide which generated operations are appropriate to expose; generation does not decide your product’s authorization policy. Schema definition guide Choosing Simfinity.js
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How to initialize PostgreSQL and serve the API
The PostgreSQL quick start uses a supplied database pool and a named schema. Initialize storage asynchronously before accepting GraphQL requests. The SQL plugin form is createSQL({ plugin: postgresPlugin({ pool, schema }) }); the createPostgres({ pool, schema }) convenience facade remains supported. The application owns the pool lifecycle, including closing it. PostgreSQL quick start SQL core and plugins
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- Provide PostgreSQL connectivity. Create or obtain a pool using your deployment’s connection configuration, then pass it and the chosen schema to the PostgreSQL storage setup.
- Initialize storage. Await the documented database initialization in the create or validation mode appropriate to your environment before the server handles operations.
- Attach the schema to an HTTP GraphQL server. For example, the guide demonstrates serving the resulting schema with Yoga. Your application remains responsible for the HTTP server lifecycle, credentials, deployment environment, and pool shutdown. PostgreSQL quick start Introduction
The exact compatibility guidance in the official PostgreSQL quick start identifies Node.js >=18.18.0, GraphQL 16, and PostgreSQL 15, 16, and 18; its starter example calls for Node.js 22 or newer. The npm listing describes PostgreSQL 15 or later and Node.js 18.18 or later. These requirements can change, so check the current PostgreSQL guide and package listing when installing, and align versions across Simfinity packages. The official documentation search results identify version 3.4.1 in 2026. PostgreSQL quick start
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How relation metadata maps to PostgreSQL
Relations are not merely GraphQL resolver conveniences: the PostgreSQL adapter maps them to relational storage. Model the relationship explicitly so the generated schema can preserve the intended ownership and integrity. PostgreSQL quick start
- Single reference: A field such as a season’s reference to a series becomes a UUID column at the configured connection field, or at the GraphQL field name when configured that way. The adapter adds a referencing index and a real foreign key to the target identity.
- Inverse collection: A collection on the parent does not become an array column there. Its resolver finds child records through the child’s reference field.
- Many-to-many: Represent the association with an explicit link entity, which gets its own table and foreign keys. Add uniqueness metadata if a particular pair must not occur more than once.
- Embedded objects and lists of references: These use owned tables and owner foreign keys. Distinguish owned data, where cascades may apply, from references to separate entities.
Relationship modeling limits
The guide documents several constraints that affect schema design: reciprocal lists that imply an unmodeled many-to-many relationship are rejected; whole embedded objects cannot be sorted or grouped; and arbitrary MongoDB aggregation pipelines or Mongoose-native methods have no direct PostgreSQL equivalent. PostgreSQL quick start
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What changes between PostgreSQL and MongoDB
| Concern | PostgreSQL adapter | MongoDB adapter |
|---|---|---|
| Physical storage | Generated SQL schemas and tables, UUID identities, indexes, and constraints. PostgreSQL guide | Mongoose models and MongoDB collections. Database comparison |
| Referential integrity | Native foreign keys and database constraints. PostgreSQL guide | MongoDB/Mongoose persistence semantics. Database comparison |
| Transactions | PostgreSQL transaction/session API; the guide describes repeatable-read transactions. PostgreSQL guide | Transactions through the Mongoose-backed adapter. Database comparison |
| Package and runtime | @simtlix/simfinity-postgres; the SQL core/plugin architecture is also available. SQL plugins |
@simtlix/simfinity-js facade with MongoDB-specific dependencies. Database comparison |
| Changing backends | Does not automatically migrate MongoDB data. Database comparison | Does not make a populated PostgreSQL application switch adapters at runtime. Database comparison |
Choosing an adapter is a deployment and data-model decision, not a runtime database switch or a populated-data migration. Moving an existing application between backends requires a separate migration and application-level work. Database comparison
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Generated storage does not make the application self-operating. Simfinity’s introduction assigns the application responsibility for the database connection, HTTP server, authentication mechanism, and deployment environment. Introduction
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- Database operations: Provide credentials and connection configuration, initialize storage, manage the pool, and plan backups and deployment-specific database administration.
- API exposure: Choose which generated operations to serve and enforce authentication and application-specific access rules in the surrounding application.
- Workload tuning: Review query patterns and create any indexes needed for your workload; generated relation indexes do not establish that every application query is optimized.
- Domain rules: Implement business rules that cannot be inferred from GraphQL field and relation definitions. Generated CRUD operations are not a replacement for those rules.
The documentation describes what Simfinity generates; it does not establish independent performance benchmarks or guarantee correctness for an application’s security policy. Treat the generated schema and storage as framework output that still needs review against your requirements. Choosing Simfinity.js
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