119 lines
4.4 KiB
JavaScript
119 lines
4.4 KiB
JavaScript
import { sparqlEscapeUri, sparqlEscapeString, sparqlEscapeDateTime, sparqlEscapeDate } from '../db.js';
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// Subject selection. One paged query per page; stops at ROW_LIMIT.
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const ROW_LIMIT = Number(process.env.ROW_LIMIT || 200000);
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const PAGE_SIZE = Number(process.env.SEED_PAGE_SIZE || 5000);
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export async function seed(sessionQuery, spec) {
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const subjects = [];
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let offset = 0;
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for (;;) {
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const query = seedPageQuery(spec, PAGE_SIZE, offset);
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const result = await sessionQuery(query);
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const rows = result.results.bindings.map(b => b.s.value);
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subjects.push(...rows);
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if (subjects.length > ROW_LIMIT) {
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throw new Error(`the question matches more than ${ROW_LIMIT} subjects. Add a filter, for example a date range or a bestuurseenheid.`);
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}
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if (rows.length < PAGE_SIZE) break;
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offset += PAGE_SIZE;
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}
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return subjects;
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}
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export function seedPageQuery(spec, limit, offset) {
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const parts = [];
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parts.push(`?s a ${sparqlEscapeUri(spec.targetClass)} .`);
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spec.filters.forEach((filter, fi) => {
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parts.push(hopsPattern(filter.path, `f${fi}`, '?s'));
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parts.push(constraintsPattern(filter.constraints, `f${fi}`));
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});
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return `SELECT DISTINCT ?s WHERE {
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${parts.join('\n ')}
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}
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LIMIT ${limit} OFFSET ${offset}`;
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}
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// Writes out every hop as its own triple pattern.
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// Forward: ?s <p1> ?f0_1 . ?f0_1 <p2> ?f0_v
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// Inverse: ?s ^<p1> → ?f0_1 <p1> ?s
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export function hopsPattern(hops, varPrefix, startVar) {
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let prev = startVar;
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const patterns = [];
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for (let i = 0; i < hops.length; i++) {
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const hop = hops[i];
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const isLast = i === hops.length - 1;
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const v = isLast ? `?${varPrefix}_v` : `?${varPrefix}_${i + 1}`;
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if (hop.inverse) {
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patterns.push(`${v} ${sparqlEscapeUri(hop.predicate)} ${prev} .`);
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} else {
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patterns.push(`${prev} ${sparqlEscapeUri(hop.predicate)} ${v} .`);
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}
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prev = v;
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}
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return patterns.join('\n ');
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}
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export function constraintsPattern(c, varPrefix) {
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const parts = [];
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const v = `?${varPrefix}_v`;
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if (c.hasValue) parts.push(`FILTER(${v} = ${escapeTerm(c.hasValue)})`);
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if (c.in) parts.push(`FILTER(${v} IN (${c.in.map(escapeTerm).join(', ')}))`);
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if (c.minInclusive) parts.push(`FILTER(${v} >= ${escapeTerm(c.minInclusive)})`);
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if (c.maxInclusive) parts.push(`FILTER(${v} <= ${escapeTerm(c.maxInclusive)})`);
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if (c.minExclusive) parts.push(`FILTER(${v} > ${escapeTerm(c.minExclusive)})`);
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if (c.maxExclusive) parts.push(`FILTER(${v} < ${escapeTerm(c.maxExclusive)})`);
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if (c.pattern) {
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const flags = c.flags ? `, ${sparqlEscapeString(c.flags)}` : '';
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parts.push(`FILTER(REGEX(str(${v}), ${sparqlEscapeString(c.pattern)}${flags}))`);
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}
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if (c.anyOf) {
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const alternation = c.anyOf.map(t => escapeRegexTerm(t.value)).join('|');
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const flags = c.flags ? `, ${sparqlEscapeString(c.flags)}` : ', "i"';
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parts.push(`FILTER(REGEX(str(${v}), ${sparqlEscapeString(alternation)}${flags}))`);
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}
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if (c.minCount === 2) {
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// two distinct leaf values on the same path
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const w = `?${varPrefix}_w`;
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parts.push(hopsPattern2(c, varPrefix, w));
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parts.push(`FILTER(${v} != ${w})`);
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}
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if (c.maxCount === 0) {
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parts.push(`FILTER NOT EXISTS { ${hopsPattern(c.path, varPrefix + '_nex', '?s')} }`);
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}
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return parts.join('\n ');
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}
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function hopsPattern2(filter, varPrefix, wVar) {
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// repeat the path to a second leaf variable
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const hops = filter.path.map(h => ({ ...h }));
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let prev = '?s';
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const patterns = [];
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for (let i = 0; i < hops.length; i++) {
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const hop = hops[i];
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const isLast = i === hops.length - 1;
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const v = isLast ? wVar : `?${varPrefix}_2_${i + 1}`;
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if (hop.inverse) patterns.push(`${v} ${sparqlEscapeUri(hop.predicate)} ${prev} .`);
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else patterns.push(`${prev} ${sparqlEscapeUri(hop.predicate)} ${v} .`);
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prev = v;
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}
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return patterns.join('\n ');
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}
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function escapeTerm(t) {
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if (t.type === 'uri') return sparqlEscapeUri(t.value);
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if (t.datatype === 'http://www.w3.org/2001/XMLSchema#dateTime')
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return sparqlEscapeDateTime(new Date(t.value));
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if (t.datatype === 'http://www.w3.org/2001/XMLSchema#date')
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return sparqlEscapeDate(new Date(t.value));
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if (t.datatype === 'http://www.w3.org/2001/XMLSchema#integer')
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return Number(t.value);
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if (t.datatype === 'http://www.w3.org/2001/XMLSchema#boolean')
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return t.value === 'true';
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return sparqlEscapeString(t.value);
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}
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function escapeRegexTerm(s) {
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return s.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
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} |