50 lines
1.7 KiB
JavaScript
50 lines
1.7 KiB
JavaScript
import _ from "lodash";
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/**
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* Topologically order tables so referenced (parent) tables come before the
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* tables that reference them. Declaration order is kept wherever the FK
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* graph allows it.
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*
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* - Self references (e.g. `comments.parent_comment_id`) are ignored.
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* - References to tables outside the schema are ignored.
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* - Cycles do not throw: a table already on the current path is skipped,
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* so every table is still emitted exactly once. Foreign keys are not
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* enforced during the sync, so cycles are safe.
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*/
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export default function orderDBSchema({ db_schema, }) {
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const new_db_schema = _.cloneDeep(db_schema);
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const tables = new_db_schema.tables;
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const tables_by_name = new Map();
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for (const table of tables) {
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if (table)
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tables_by_name.set(table.tableName, table);
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}
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const ordered = [];
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const visited = new Set();
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const visiting = new Set();
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function visit(table) {
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if (visited.has(table.tableName) || visiting.has(table.tableName)) {
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return;
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}
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visiting.add(table.tableName);
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for (const field of table.fields || []) {
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const dst_table_name = field?.foreignKey?.destinationTableName;
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if (!dst_table_name || dst_table_name === table.tableName) {
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continue;
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}
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const fk_table = tables_by_name.get(dst_table_name);
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if (fk_table) {
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visit(fk_table);
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}
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}
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visiting.delete(table.tableName);
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visited.add(table.tableName);
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ordered.push(table);
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}
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for (const table of tables) {
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if (table)
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visit(table);
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}
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new_db_schema.tables = ordered;
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return new_db_schema;
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}
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