snapshot

Migration Snapshot

Handles schema snapshots for migration diffing. Snapshots capture the current state of table schemas and are stored as JSON between migration runs to detect changes.

Types

ColumnSnapshot

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Snapshot of a single column’s properties including name, type, nullability, and whether it has a default value.

pub type ColumnSnapshot {
  ColumnSnapshot(
    name: String,
    column_type: String,
    nullable: Bool,
    has_default: Bool,
  )
}

Constructors

ColumnSnapshot(
  name: String,
  column_type: String,
  nullable: Bool,
  has_default: Bool,
)

Snapshot

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Snapshot of all table schemas, stored as JSON between runs. Used to detect what has changed since the last migration by comparing against the current schema definitions.

pub type Snapshot {
  Snapshot(tables: dict.Dict(String, TableSnapshot))
}

Constructors

Snapshot(tables: dict.Dict(String, TableSnapshot))

TableSnapshot

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Snapshot of a single table’s column definitions. Contains the list of columns in their definition order for accurate migration diffing.

pub type TableSnapshot {
  TableSnapshot(columns: List(ColumnSnapshot))
}

Constructors

TableSnapshot(columns: List(ColumnSnapshot))

Values

build

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pub fn build(tables: List(schema_parser.Table)) -> Snapshot

Build a new snapshot from a list of parsed Table schemas. Converts each table’s columns to ColumnSnapshot format for JSON serialization.

column_type_to_string

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pub fn column_type_to_string(
  col_type: schema_parser.ColumnType,
) -> String

Convert a ColumnType to its string representation for snapshots. Maps each variant to a consistent string format used in the JSON snapshot files.

load

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pub fn load(path: String) -> Snapshot

Load the schema snapshot from a JSON file. Returns an empty snapshot if the file doesn’t exist or can’t be parsed, allowing first-run migration generation.

merge

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pub fn merge(old: Snapshot, new: Snapshot) -> Snapshot

Merge new snapshot into old snapshot (used when filtering by model). Tables in the new snapshot will overwrite those in the old snapshot, but tables only in the old snapshot are preserved.

save

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pub fn save(path: String, snapshot: Snapshot) -> Result(Nil, Nil)

Save a snapshot to a JSON file. Serializes the snapshot to formatted JSON for readability and writes to the specified path.