103 lines
1.9 KiB
JavaScript
103 lines
1.9 KiB
JavaScript
const TOKEN_MAP = {
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EQUALS: "===",
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LT: "<",
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LTE: "<=",
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MT: ">",
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MTE: ">=",
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CONTAINS: "includes",
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AND: "&&",
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OR: "||",
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}
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const SCHEMA_MAP = {
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stats: {
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group: {
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type: "string"
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},
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sum: {
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type: "number"
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},
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min: {
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type: "number"
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},
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max: {
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type: "number"
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},
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count: {
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type: "number"
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},
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sumsqr: {
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type: "number"
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},
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avg: {
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type: "number"
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}
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}
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}
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/**
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* Iterates through the array of filters to create a JS
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* expression that gets used in a CouchDB view.
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* @param {Array} filters - an array of filter objects
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* @returns {String} JS Expression
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*/
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function parseFilterExpression(filters) {
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const expression = []
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for (let filter of filters) {
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if (filter.conjunction) expression.push(TOKEN_MAP[filter.conjunction]);
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if (filter.condition === "CONTAINS") {
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expression.push(
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`doc["${filter.key}"].${TOKEN_MAP[filter.condition]}("${
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filter.value
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}")`)
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return
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}
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expression.push(`doc["${filter.key}"] ${TOKEN_MAP[filter.condition]} "${
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filter.value
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}"`)
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}
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return expression.join(" ")
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}
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function parseEmitExpression(field, groupBy) {
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if (field) return `emit(doc["${groupBy || "_id"}"], doc["${field}"]);`
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return `emit(doc._id);`
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}
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function viewTemplate({
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field,
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modelId,
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groupBy,
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filters = [],
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calculation
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}) {
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const parsedFilters = parseFilterExpression(filters)
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const filterExpression = parsedFilters ? `&& ${parsedFilters}` : ""
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const emitExpression = parseEmitExpression(field, groupBy)
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const reduction = field ? { reduce: "_stats" } : {}
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return {
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meta: {
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field,
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modelId,
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groupBy,
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filters,
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schema: SCHEMA_MAP[calculation],
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calculation
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},
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map: `function (doc) {
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if (doc.modelId === "${modelId}" ${filterExpression}) {
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${emitExpression}
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}
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}`,
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...reduction
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}
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}
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module.exports = viewTemplate
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