initial part-tested edition

2022-10-18 22:04:00 +01:00
parent 361fc2f7f4
commit e9586859bd
9 changed files with 577 additions and 5 deletions
@@ -0,0 +1,305 @@
+import { Document } from 'arangojs/documents'
+import { DocumentCollection } from 'arangojs/collection'
+import { GeneratedAqlQuery } from 'arangojs/aql'
+import { Database, aql } from 'arangojs'
+
+/**
+ * A `CountFn` function returns the number of documents in a single collection matching search `terms` given.
+ *
+ * `count()` provides the standard implementation.
+ */
+export type CountFn<T extends Searchable, S extends Searchable = T> = (
+  terms?: Terms<Document<DeepNonNullable<S>>>
+) => Promise<number>
+
+/**
+ * Recursively renders all of a complex object's properties required, non-null, and non-undefined.
+ *
+ * Note: this type recurses through objects only, not arrays.
+ */
+export type DeepNonNullable<T> = NonNullable<T> extends object ? { [P in keyof T]-?: DeepNonNullable<T[P]> } : T
+
+/** Query sort direction. */
+export type Direction = 'ASC' | 'DESC'
+
+/**
+ * Simple search filter type in which any number of conditions can be specified for a presumed parameter.
+ *
+ * Multiple operators can be used in combination.
+ * By default they will be combined into an `AND` filter.
+ * Specify `mode: "OR"` to switch to an `OR` filter.
+ *
+ * Note: `LIKE`, `NOT LIKE`, and regular expression operators are only available if `T` extends `string`.
+ */
+export type Filter<T> = {
+  mode?: 'AND' | 'OR'
+  eq?: T | null
+  gt?: T
+  gte?: T
+  in?: T[]
+  like?: T & string
+  lt?: T
+  lte?: T
+  neq?: T | null
+  nin?: T[]
+  nlike?: T & string
+  nreg?: T & string
+  reg?: T & string
+}
+
+/**
+ * A `FindFn` function returns the first document in a single collection matching search `terms` given.
+ * A `sort` can be specified to control the result.
+ *
+ * `find()` provides the standard implementation.
+ */
+export type FindFn<T extends Searchable, S extends Searchable = T> = (
+  terms?: Terms<Document<DeepNonNullable<S>>>,
+  sort?: Sort<Document<T>>[] | Sort<Document<T>>
+) => Promise<Document<T> | undefined>
+
+/**
+ * Query limit.
+ * Always a tuple, but the second value can be omitted.
+ */
+export type Limit = [number, number?]
+
+/**
+ * Searchable data type.
+ * Essentially, any object is valid.
+ */
+export type Searchable = Record<string, unknown>
+
+/**
+ * Formulate search terms based on a complex data type.
+ * Nested object types are preserved, while scalar properties are converted to `Filter` representations.
+ */
+export type Terms<T> = {
+  [P in keyof T]?: NonNullable<NonNullable<T[P]> extends object ? Terms<T[P]> : Filter<T[P]>>
+}
+
+/**
+ * A `SearchFn` function matches documents in a single collection and returns a `SearchResult` based on the given
+ * `terms`, `limit`, and `sort`.
+ */
+export type SearchFn<T extends Searchable, S extends Searchable = T> = (
+  terms?: Terms<Document<DeepNonNullable<S>>>,
+  limit?: Limit,
+  sort?: Sort<Document<T>>[] | Sort<Document<T>>
+) => Promise<SearchResult<T>>
+
+/**
+ * Search results are a tuple of three values:
+ *   1. The **total** number of matching documents in the searched collection, ignoring limit
+ *   2. The documents matched within the searched collection, respecting limit
+ *   3. The AQL query object for the latter (for debugging purposes)
+ */
+export type SearchResult<T extends Searchable> = [number, Document<T>[], GeneratedAqlQuery]
+
+/** Query sort order. */
+export type Sort<T> = [keyof T, Direction]
+
+/** Format scalar or scalar array data for use in AQL. */
+export const formatData = <T>(data: T | T[]): string =>
+  data instanceof Array ? `[${data.map(formatValue).join(',')}]` : formatValue(data)
+
+/** Format scalar data for use in AQL. */
+export const formatValue = <T>(data: T): string => {
+  if (typeof data === 'string') return `"${data}"`
+  if (data === null) return 'null'
+  return `${data}`
+}
+
+/** Map of search operator properties to AQL equivalents. */
+export const operatorMap: Record<keyof Omit<Filter<unknown>, 'mode'>, string> = {
+  eq: '==',
+  gt: '>',
+  gte: '>=',
+  in: 'IN',
+  like: 'LIKE',
+  lt: '<',
+  lte: '<=',
+  neq: '!=',
+  nin: 'NOT IN',
+  nlike: 'NOT LIKE',
+  nreg: '!~',
+  reg: '=~'
+}
+
+/** Search operators. */
+export const operators = Object.keys(operatorMap)
+
+/**
+ * Parse a search limit to a string AQL limit.
+ *
+ * Note: `LIMIT` is not prepended.
+ */
+export const parseLimit = (l: Limit) => l.length > 1 ? `${l[0]}, ${l[1]}` : l[0]
+
+/**
+ * Parse a search filter to a string of AQL filters.
+ *
+ * Note: `FILTER` is not prepended.
+ */
+export const parseFilter = <T>(param: string, search: Filter<T>) => parseFilterOps(search)
+  .map(([op, data]) => `${param} ${op} ${formatData(data)}`)
+  .join(` ${search.mode || 'AND'} `)
+
+/** Parse search parameter object to FILTER statement(s). */
+const parseFilterOps = <T>(search: Filter<T>) =>
+  (Object.keys(search) as (keyof typeof search)[]).map(key => {
+    if (key === 'mode' || search[key] === undefined) return undefined
+    if (operatorMap[key] === undefined) throw new Error('unrecognised search operator')
+    return [operatorMap[key], search[key]]
+  }).filter(Boolean) as [string, T | T[] | null][]
+
+/**
+ * Parse query sort(s) to an array of string AQL sorts.
+ *
+ * Note: `SORT` is not prepended.
+ */
+export const parseSort = <T>(s: Sort<T>[] | Sort<T>, parent: string): string[] => {
+  if (s[0] instanceof Array) return (s as Sort<T>[]).map(ss => `${parent}.${String(ss[0])} ${ss[1]}`)
+  return [`${parent}.${String(s[0])} ${s[1]}`]
+}
+
+/**
+ * Parse search terms to a flat array of search filters.
+ * The `parent` argument refers to the current document, and is prefixed to each filter.
+ */
+export const parseTerms = <T>(s: Terms<T>, parent: string) => (Object.keys(s) as (keyof T)[])
+  .reduce((filters, param) => {
+    const f = s[param]
+    if (!f) return filters
+    if (Object.keys(f).find(k => k !== 'mode' && !operators.includes(k))) {
+      // object is nested
+      filters.push(...parseTerms(f as Terms<typeof f>, `${parent}.${String(param)}`))
+    }
+    else {
+      // object resembles a search parameter
+      filters.push(parseFilter(`${parent}.${String(param)}`, f))
+    }
+    return filters
+  }, <string[]>[])
+
+/**
+ * Build and execute a count query that matches documents in a single collection.
+ * Returns the total number of matches.
+ *
+ * This example resembles the generated AQL query:
+ *
+ * ```aql
+ * FOR {i} IN {c} {FILTER ...} COLLECT WITH COUNT INTO {n} RETURN {n}
+ * ```
+ */
+export const count = <T extends Searchable, S extends Searchable = T>(
+  db: Database,
+  c: DocumentCollection<T>,
+  i = 'i',
+  n = 'n'
+): CountFn<T, S> => async (terms) => {
+    const filters = terms && parseTerms(terms, i)
+    const filterStr = aql.literal(filters ? filters.map(f => `FILTER ${f}`).join(' ') : '')
+    const l = { i: aql.literal(i), n: aql.literal(n) }
+
+    const countQuery = aql`
+      FOR ${l.i} IN ${c}
+        ${filterStr}
+        COLLECT WITH COUNT INTO ${l.n}
+        RETURN ${l.n}
+    `
+
+    return await (await db.query(countQuery)).next()
+  }
+
+/**
+ * Build and execute a find query that returns the first matching document in a single collection.
+ *
+ * This example resembles the generated AQL query:
+ *
+ * ```aql
+ * FOR {i} IN {collection} {FILTER ...} {SORT ...} LIMIT 1 RETURN {i}
+ * ```
+ */
+export const find = <T extends Searchable, S extends Searchable = T>(
+  db: Database,
+  c: DocumentCollection<T>,
+  i = 'i'
+): FindFn<T, S> => async (terms, sort = ['_key', 'ASC']) => {
+    const filters = terms && parseTerms(terms, 'i')
+    const filterStr = aql.literal(filters ? filters.map(f => `FILTER ${f}`).join(' ') : '')
+    const sortStr = aql.literal(sort ? `SORT ${parseSort(sort, 'i').join(', ')}` : '')
+    const l = { i: aql.literal(i) }
+
+    const query = aql`
+      FOR ${l.i} IN ${c}
+        ${filterStr}
+        ${sortStr}
+        LIMIT 1
+        RETURN ${l.i}
+    `
+
+    const data = await (await db.query(query)).next()
+    return data
+  }
+
+/**
+ * Build and execute a search query across a single collection.
+ * Returns a `SearchResult` tuple containing the total number of matches (ignoring limit), all matching documents
+ * (respecting limit), and the AQL query.
+ *
+ * This example resembles the generated AQL query:
+ *
+ * ```aql
+ * FOR {i} IN {collection} {FILTER ...} {SORT ...} {LIMIT ...} RETURN {i}
+ * ```
+ */
+export const search = <T extends Searchable, S extends Searchable = T>(
+  db: Database,
+  c: DocumentCollection<T>,
+  i = 'i',
+  n = 'n'
+): SearchFn<T, S> => async (terms, limit, sort = ['_rev', 'ASC']) => {
+    const filters = terms && parseTerms(terms, 'i')
+    const filterStr = aql.literal(filters ? filters.map(f => `FILTER ${f}`).join(' ') : '')
+    const limitStr = aql.literal(limit ? `LIMIT ${parseLimit(limit)}` : '')
+    const sortStr = aql.literal(sort ? `SORT ${parseSort(sort, 'i').join(', ')}` : '')
+    const l = { i: aql.literal(i), n: aql.literal(n) }
+
+    let count = 0
+    if (limit) {
+      const countQuery = aql`
+        FOR ${l.i} IN ${c}
+          ${filterStr}
+          COLLECT WITH COUNT INTO ${l.n}
+          RETURN ${l.n}
+      `
+      count = await (await db.query(countQuery)).next()
+    }
+
+    const query = aql`
+      FOR ${l.i} IN ${c}
+        ${filterStr}
+        ${sortStr}
+        ${limitStr}
+        RETURN ${l.i}
+    `
+
+    const data = await (await db.query(query)).all()
+    if (data.length > count) count = data.length
+    return [count, data, query]
+  }
+
+export default {
+  count,
+  find,
+  formatData,
+  formatValue,
+  operatorMap,
+  operators,
+  parseFilter,
+  parseLimit,
+  parseSort,
+  parseTerms,
+  search
+}