3/28/2023 0 Comments Javascript json queryIf the shape of the payload is fixed, based on the property name (for example, all properties called registry hold Map objects)."Guess" based on the structure of the data (for example, an array of two-member arrays).Serialize the entire object to a string and prefix it with a type tag. log (map2 ) // Map īecause JSON has no syntax space for annotating type metadata, in order to revive values that are not plain objects, you have to consider one of the following: JsonText, ( key, value ) => (key = "" ? new Map (value ) : value ), ) Ĭonsole. Map, ( key, value ) => (value instanceof Map ? Array. const map = new Map (, ,, ] ) const jsonText = JSON. We can use the replacer to specify the entries to be serialized. Maps are normally serialized as objects with no properties. To transfer large numbers without loss of precision, serialize them as strings, and revive them to BigInts, or other appropriate arbitrary precision formats. So, for example, numbers in JSON text will have already been converted to JavaScript numbers, and may lose precision in the process. Note that reviver is run after the value is parsed. Note that despite the method being named json (), the result is not JSON but is instead the result of taking JSON as input and parsing it to produce a JavaScript. It returns a promise which resolves with the result of parsing the body text as JSON. For JSON text parsing to primitive values, reviver will be called once. The json () method of the Response interface takes a Response stream and reads it to completion. Similar to the replacer parameter of JSON.stringify(), reviver will be last called on the root object with an empty string as the key and the root object as the value. If the reviver only transforms some values and not others, be certain to return all untransformed values as-is - otherwise, they will be deleted from the resulting object. Otherwise, the property is redefined to be the return value. If the reviver function returns undefined (or returns no value - for example, if execution falls off the end of the function), the property is deleted from the object. The reviver is called with the object containing the property being processed as this, and two arguments: key and value, representing the property name as a string (even for arrays) and the property value. Specifically, the computed value and all its properties (in a depth-first fashion, beginning with the most nested properties and proceeding to the original value itself) are individually run through the reviver. non-ascii non-word characters are no-longer valid in member identifier names use quoted subscript strings instead (e.g., $ instead of $.If a reviver is specified, the value computed by parsing is transformed before being returned.subscripts no longer act as character slices on string elements.and characters not referring to instance variables final step arguments in slice operators may now be negative.strings in subscripts may now be double-quoted.Other Minor DifferencesĪs a result of using a real parser and static evaluation, there are some arguable bugs in the original library that have not been carried through here: We dont have enough information about .uk safety, we need to dig a little deeper before we make the call. With filters and grouping it can be used as a simple business intelligence solution to delve deep into your data. The original regex approach can sometimes be forgiving for better or for worse (e.g., $ => $), and in other cases, can be just plain wrong (e.g. JSON Query is an interactive web-based tool to query big, flat arrays of JSON. This project uses a formal BNF grammar to parse JSONPath expressions, an attempt at reverse-engineering the intent of the original implementation, which parses via a series of creative regular expressions. See more details in the implementation of the evaluator. This method is even safer than vm.runInNewContext, since the script engine itself is more limited and entirely distinct from the one running the application code. So for example, will be just fine to match arrays with more than ten elements, but ?(process.exit()) will not get evaluated since process would yield a ReferenceError. That means both that the scope is limited to the instance variable ( and only simple expressions (with no side effects) will be valid. Script expressions (i.e, (.) and ?(.)) are statically evaluated via static-eval rather than using the underlying script engine directly. This implementation aims to be compatible with Stefan Goessner's original implementation with a few notable exceptions described below. stringify ( ) // "$." Differences from Original Implementation Returns only first count elements if specified. Returns an array of elements that satisfy the provided JSONPath expression, or an empty array if none were matched. Methods jp.query(obj, pathExpression)įind elements in obj matching pathExpression. The first two books via subscript array all books with isbn all books cheaper than all books that cost & all fiction books cheaper than 30 All things in store, which are some books and a red bicycle
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