59 lines
2.2 KiB
Markdown
59 lines
2.2 KiB
Markdown
[](https://travis-ci.org/yalp/jsonpath)
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This was mostly an experiment to learn go and test using closures to interpret a JSON path.
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You should use https://github.com/PaesslerAG/jsonpath instead.
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# jsonpath
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a (partial) implementation in [Go](http://golang.org) based on [Stefan Goener JSON Path](http://goessner.net/articles/JsonPath/)
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## Limitations
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* No support for subexpressions : `$books[(@.length-1)]`
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* No support for filters : `$books[?(@.price > 10)]`
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* Strings in brackets must use double quotes : `$["bookstore"]`
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* Cannot operate on struct fields
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The third limitation comes from using the `text/scanner` package from the standard library.
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The last one could be overcome by using reflection.
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## JsonPath quick intro
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All expressions start `$`.
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Examples (supported by the current implementation) :
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* `$` the current object (or array)
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* `$.books` access to the key of an object (or `$["books"]`with bracket syntax)
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* `$.books[1]` access to the index of an array
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* `$.books[1].authors[1].name` chaining of keys and index
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* `$["books"][1]["authors"][1]["name"]` the same with braket syntax
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* `$.books[0,1,3]` union on an array
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* `$["books", "songs", "movies"]` union on an object
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* `$books[1:3]` second and third items of an array
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* `$books[:-2:2]` every two items except the last two of an array
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* `$books[::-1]` all items in reversed order
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* `$..authors` all authors (recursive search)
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Checkout the [tests](jsonpath_test.go) for more examples.
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## Install
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go get github.com/yalp/jsonpath
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## Usage
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A jsonpath applies to any JSON decoded data using `interface{}` when decoded with [encoding/json](http://golang.org/pkg/encoding/json/) :
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var bookstore interface{}
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err := json.Unmarshal(data, &bookstore)
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authors, err := jsonpath.Read(bookstore, "$..authors")
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A jsonpath expression can be prepared to be reused multiple times :
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allAuthors, err = jsonpath.Prepare("$..authors")
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...
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var bookstore interface{}
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err := json.Unmarshal(data, &bookstore)
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authors, err := allAuthors(bookstore)
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The type of the values returned by the `Read` method or `Prepare` functions depends on the jsonpath expression.
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