xml2js-xpath
Version:
Search xml2js JSON documents with XPath query strings.
359 lines (271 loc) • 8.73 kB
JavaScript
;
let _ = require("lodash");
const ATTRKEY = '$';
const CHARKEY = '_'; // Definition of an XML name tag: https://www.w3.org/TR/xml/#NT-Name
const NAME_START_CHAR = 'A-Za-z:_\xC0-\xD6\xD8-\xF6\xF8-\u02FF\u0370-\u037D' + '\u037F-\u1FFF\u200C-\u200D\u2070-\u218F\u2C00-\u2FEF\u3001-\uD7FF' + '\uF900-\uFDCF\uFDF0-\uFFFD';
const NAME_CHAR = `${NAME_START_CHAR}.0-9·\u0300-\u036F\u203F-\u2040-`;
const TAG_NAME = `[${NAME_START_CHAR}][${NAME_CHAR}]*`;
const TAG_AND_PROP = `(${TAG_NAME})\\[@([\\w:]+)='([^']+)'\\]`;
const TAG_AND_CHILD = `(${TAG_NAME})\\[([\\w:]+)='([^']+)'\\]`;
const TAG_AND_POSITION = `(${TAG_NAME})\\[([\\d]+)\\]`; // Given a JSON document returned by xml2js (with _ and $ keys), return the
// combined text value of the tags.
let jsonText = function (json) {
if (_.isString(json)) {
return json;
}
let result = json[CHARKEY] || '';
_.forEach(_.keys(json), function (key) {
if (key === ATTRKEY || key === CHARKEY) {
return;
}
let value = json[key];
if (_.isArray(value)) {
_.forEach(value, function (entry) {
result += jsonText(entry);
});
} else {
result += jsonText(value);
}
});
return result;
};
let findAllKeys = function (json, key, matches) {
if (_.isString(json)) {
return matches;
}
_.forEach(_.keys(json), function (jsonKey) {
if (jsonKey === ATTRKEY || jsonKey === CHARKEY) {
return;
}
if (key === jsonKey && key in json) {
if (!_.isArray(json[jsonKey])) {
matches.push(json[jsonKey]);
} else {
_.forEach(json[jsonKey], function (val) {
matches.push(val);
});
}
} else {
findAllKeys(json[jsonKey], key, matches);
}
});
return matches;
};
let findAllProperties = function (json, property, matches) {
let foundMatch = false;
_.forEach(_.keys(json.$), function (jsonProperty) {
if (property === jsonProperty && property in json.$) {
matches.push(json);
foundMatch = true;
}
});
if (!foundMatch) {
_.forEach(_.keys(json), function (jsonKey) {
if (jsonKey === ATTRKEY || jsonKey === CHARKEY) {
return;
}
findAllProperties(json[jsonKey], property, matches);
});
}
return matches;
}; // Perform simple search of a xml2js document with XPath.
//
// This function supports simple XPath queries like:
// * //Element/SubElement
// * /Element/Subelement/SubSubElement
// * //Element[@id='4']/SubElement
// * //Element[@id='4']/@property
//
// Returns an array of matches.
let find = function (json, path) {
if (path === "") {
if (!_.isArray(json)) {
return [json];
}
return json;
}
if (path.length > 0 && path[0] === ".") {
path = path.substring(1);
} // match /Element[@key='value']
let match = path.match(`^\\/${TAG_AND_PROP}`);
if (match) {
let node = match[1];
let key = match[2];
let value = match[3];
let newPath = path.replace(`/${node}[@${key}='${value}']`, "");
if (node in json) {
if (ATTRKEY in json[node]) {
if (key in json[node][ATTRKEY] && json[node][ATTRKEY][key] === value) {
return find(json[node], newPath);
}
} else if (_.isArray(json[node])) {
let results = [];
_.forEach(json[node], function (item) {
if (ATTRKEY in item && key in item[ATTRKEY] && item[ATTRKEY][key] === value) {
let hits = find(item, newPath);
results = results.concat(hits);
}
});
return results;
}
}
} // match //Element[@key='value']
match = path.match(`^\\/\\/${TAG_AND_PROP}`);
if (match) {
// see if the current dictionary has a match, for all that do not match, see
// if their values have matches, etc...
let node = match[1];
let key = match[2];
let value = match[3];
let newPath = path.replace(`//${node}[@${key}='${value}']`, "");
let foundKeys = findAllKeys(json, node, []);
let matches = _.filter(foundKeys, function (val) {
if (ATTRKEY in val) {
return key in val[ATTRKEY] && val[ATTRKEY][key] === value;
}
return false;
});
let results = [];
_.forEach(matches, function (item) {
let hits = find(item, newPath);
results = results.concat(hits);
});
return results;
} // match /Element[SubElement1='value']
match = path.match(`^\\/${TAG_AND_CHILD}`);
if (match) {
let node = match[1];
let key = match[2];
let value = match[3];
let newPath = path.replace(`/${node}[${key}='${value}']`, "");
if (node in json) {
if (key in json[node]) {
if (json[node][key] === value) {
return find(json[node], newPath);
}
} else if (_.isArray(json[node])) {
let results = [];
_.forEach(json[node], function (item) {
if (jsonText(item[key]) === value) {
let hits = find(item, newPath);
results = results.concat(hits);
}
});
return results;
}
}
} // match //Element
match = extractAllKeys(json, path, new RegExp(`^//(${TAG_NAME})`));
if (match) {
return match;
} // match intermediate /Element/
match = path.match(`^\\/(${TAG_NAME})\\/`);
if (match) {
const node = match[1];
if (_.isArray(json[node])) {
let results = [];
json[node].forEach(sub => results = results.concat(find(sub, path.replace(`/${node}/`, "/"))));
return results;
} else {
return find(json[node], path.replace(`/${node}/`, "/"));
}
} // match /Element[\d+] (with numeric positional predicate)
match = path.match(`^\\/${TAG_AND_POSITION}`);
if (match) {
const node = match[1];
const position = +match[2]; // xpath is one-based indexed, js-array is zero-based!
let newPath = path.replace(`/${node}[${position}]`, "");
if (_.has(json, node)) {
if (_.isArray(json[node])) {
return json[node][position - 1] ? find(json[node][position - 1], newPath) : [];
}
}
} // match leaf /Element
match = path.match(`^\\/(${TAG_NAME})$`);
if (match) {
const node = match[1];
if (_.has(json, node)) {
if (_.isArray(json[node])) {
return json[node];
} else {
return [json[node]];
}
}
} // match //@property
match = extractAllProperties(json, path, /^\/\/@([\w:]+)/);
if (match) {
return match;
} // match /@property
match = path.match(/^\/@([\w:]+)/);
if (match) {
let matches = [];
_.forEach(_.keys(json), function (key) {
if (_.isArray(json[key])) {
_.forEach(json[key], function (sub) {
if (_.has(sub, ATTRKEY) && match[1] in sub[ATTRKEY]) {
matches.push(sub);
}
});
} else {
if (_.has(json, ATTRKEY) && match[1] in json[ATTRKEY]) {
matches.push(json);
}
}
});
return matches;
}
return [];
};
let extractAll = function (json, path, pattern, extractFn) {
let match = path.match(pattern);
if (match) {
// see if the current dictionary has a match, for all that do not match, see
// if their values have matches, etc...
let newPath = path.replace(pattern, '');
let matches = extractFn(json, match[1], []);
let results = [];
_.forEach(matches, function (value) {
let matches = find(value, newPath);
results = results.concat(matches);
});
return results;
}
return false;
};
let extractAllKeys = _.partialRight(extractAll, findAllKeys);
let extractAllProperties = _.partialRight(extractAll, findAllProperties); // Use find to search a JSON object.
//
// Parameters:
// * json = the JSON document to search (genearted by xml2js)
// * path = An XPath search.
// * fetch = If true, run jsonText() on the output. If a string, try to return
// the tag property. If not supplied, return the node.
//
// Returns a node (one with no attributes and a null value if no match)
// If more than one match is found, the first is returned.
let evalFirst = function (json, path, fetch) {
let matches = find(json, path);
if (matches.length === 0) {
if (fetch) {
return undefined;
}
return undefined;
} // searches like //Somehting/SomethingElse return nested arrays
matches = matches[0];
if (_.isArray(matches)) {
matches = matches[0];
}
if (fetch === true) {
return jsonText(matches);
}
if (_.isString(fetch)) {
if (ATTRKEY in matches && fetch in matches[ATTRKEY]) {
return matches[ATTRKEY][fetch];
}
return undefined;
}
return matches;
};
module.exports.evalFirst = evalFirst;
module.exports.find = find;
module.exports.jsonText = jsonText;