add json parser #140

dschadd · 2023-04-24T20:54:36Z

Items Addressed

Issue
This feature was intended to allow for json to be passed to Decanter without a custom parser.
This feature is intended for PostgreSQL column types of json or jsonb
This feature is not intended to accept or "bypass" large json blob data sent over from UI to a Rails JSON API. It is column specific.

Author Checklist

Add unit test(s)
Update documentation (if necessary)
Update version in version.rb following versioning guidelines

dschadd · 2023-04-25T17:06:41Z

lib/decanter/parser/json_parser.rb

+module Decanter
+  module Parser
+    class JsonParser < ValueParser
+


Since json is not a native Ruby data type, there is no specific allowed types. Instead all values passed to this parser will be parsed by JSON.parse(val), unless they are nil or blank strings.

dschadd · 2023-04-25T17:07:03Z

lib/decanter/parser/json_parser.rb

+    class JsonParser < ValueParser
+
+      parser do |val, options|
+        raise Decanter::ParseError.new 'Expects a JSON string' if val.is_a?(Array) || val.is_a?(Hash)


JSON.parse only accepts string type as an argument

Forgive my ignorance here – does ActiveRecord require that the input to create/update is a hash? Or will it accept a serialized JSON string?

What's the benefit of checking for an Array or a Hash as opposed to is_a? String?

I'm having a hard time finding exact documentation, but I don't think there is a specific requirement for it to be hash. Mainly because JSON can be an array, hash, string

I think I had it this way just for readability as to avoid unless, but looking at it again I'm not sure that's any more readable. I think I'll change it to unless is_a? String

This line in particular is difficult since JSON can be many things. I almost decided to remove this entirely, but wanted to keep some error message here. I could make an argument for having no error message here, but that felt wrong?

I leaned into the fact the client will send it as a string, I will check that, and then the code on line 8 will parse it to become a JSON object for Rails to use

From some quick testing in the console, it looks like JSON.parse throws an error for anything that's not a string (including booleans, integers, etc).

Because of that, to me the most readable option seems like unless is_a? String, but I also wonder if a readable alternative could be rescuing from a JSON.parse error to tell the dev that the value is not valid JSON.

dschadd · 2023-04-25T17:07:42Z

lib/decanter/version.rb

@@ -1,3 +1,3 @@
 module Decanter
-  VERSION = '4.0.1'.freeze
+  VERSION = '4.0.2'.freeze


Not 100% sure on versioning semantics for minor feature. I suppose this could be 4.1?

This is a backwards compatible feature, which warrants a minor bump (i.e., 4.1.0)

dschadd · 2023-04-25T17:17:48Z

I had trouble updating the versioning for this. I updated version.rb, ran bundle install and pushed and got a fail. Tried it a few different ways with no success. What am I doing wrong?

chawes13 · 2023-05-23T13:59:14Z

lib/decanter/parser/json_parser.rb

@@ -0,0 +1,12 @@
+module Decanter
+  module Parser
+    class JsonParser < ValueParser


I believe this should inherit from HashParser

See https://github.com/LaunchPadLab/decanter#custom-parser-base-classes

Ah, that doesn't account for the fact that it could be an array. NVM!

Yea it turns out that JSON is anything lol

chawes13 · 2023-05-23T14:03:10Z

lib/decanter/parser/json_parser.rb

+    class JsonParser < ValueParser
+
+      parser do |val, options|
+        raise Decanter::ParseError.new 'Expects a JSON string' if val.is_a?(Array) || val.is_a?(Hash)


What's the benefit of checking for an Array or a Hash as opposed to is_a? String?

nicoledow

@dschadd Bumping - are you still interested and do you still have capacity to address the comments below to get this into an upcoming release? Aiming for the end of the quarter.

nicoledow · 2025-03-07T15:23:37Z

spec/decanter/parser/json_parser_spec.rb

+  describe '#parse' do
+    it 'parses string value and returns a parsed JSON' do
+      expect(parser.parse(name, '{"key": "value"}')).to match({name => {"key" => "value"}})
+    end
+
+    context 'with empty string' do
+      it 'returns nil' do
+        expect(parser.parse(name, '')).to match({name => nil})
+      end
+    end
+
+    context 'with nil' do
+      it 'returns nil' do
+        expect(parser.parse(name, nil)).to match({name => nil})
+      end
+    end
+  end


As mentioned here, I'd love to see a descriptive error thrown if the string can't be parsed as valid JSON. I think that would also warrant a test case here.

Might also be worth adding test cases to ensure a JSON array string (i.e. '['investment', 'early_retirement', 'saving']') and an object ('{ "first_name": "Daniel", "last_name": "Schadd" }' can both be handled.

dschadd · 2025-03-11T21:36:22Z

@dschadd Bumping - are you still interested and do you still have capacity to address the comments below to get this into an upcoming release? Aiming for the end of the quarter.

Hey @nicoledow - don't think I'll be able to get to one this quarter, but would be happy to throw this on my Q3 goals?

nicoledow · 2025-03-14T12:07:23Z

@dschadd Bumping - are you still interested and do you still have capacity to address the comments below to get this into an upcoming release? Aiming for the end of the quarter.

Hey @nicoledow - don't think I'll be able to get to one this quarter, but would be happy to throw this on my Q3 goals?

@dschadd No worries! I just wanted to get an idea of what might be in the Q1 release. Next quarter is great!

nicoledow · 2025-08-22T16:25:42Z

README.md

+- [Decanter](#decanter)
+  - [Migration Guides](#migration-guides)
+  - [Contents](#contents)
+  - [Basic Usage](#basic-usage)
+    - [Decanters](#decanters)
+    - [Generators](#generators)
+      - [Decanters](#decanters-1)
+      - [Parsers](#parsers)
+      - [Resources](#resources)
+    - [Decanting Collections](#decanting-collections)
+      - [Control Over Decanting Collections](#control-over-decanting-collections)
+    - [Nested resources](#nested-resources)
+    - [Default parsers](#default-parsers)
+    - [Parser options](#parser-options)
+    - [Exceptions](#exceptions)
+  - [Advanced Usage](#advanced-usage)
+    - [Custom Parsers](#custom-parsers)
+      - [Custom parser methods](#custom-parser-methods)
+      - [Custom parser base classes](#custom-parser-base-classes)
+    - [Squashing inputs](#squashing-inputs)
+    - [Chaining parsers](#chaining-parsers)
+    - [Requiring params](#requiring-params)
+    - [Default values](#default-values)
+    - [Global configuration](#global-configuration)
+  - [Contributing](#contributing)


Just formatting

kweingart08

@nicoledow - This looks good to me.

dschadd added 4 commits April 24, 2023 15:54

add json parser

981b15d

include spec

b950040

add spec and force json parse on everything

b111d4f

change version

1600632

dschadd commented Apr 25, 2023

View reviewed changes

dschadd added 3 commits April 25, 2023 12:10

update version in gemfile

2be0b96

fix version

e0e564f

actually fix version

21d8eb4

dschadd marked this pull request as ready for review April 25, 2023 17:17

dschadd requested a review from chawes13 as a code owner April 25, 2023 17:17

dschadd requested review from dianacamacho and kweingart08 April 25, 2023 17:18

update readme

11b9209

chawes13 reviewed May 23, 2023

View reviewed changes

nicoledow self-requested a review March 7, 2025 14:52

nicoledow reviewed Mar 7, 2025

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nicoledow linked an issue Aug 22, 2025 that may be closed by this pull request

JSON Type Parser #139

Closed

nicoledow added 8 commits August 22, 2025 10:51

Merge branch 'main' into feature/json-parse

22f51b0

refactor check if val is a string

4442067

Decanter::ParserError when invalid JSON is provided

7efe829

add additional error test cases

9961218

add additional error test cases

5e45710

rescue from all errors in JSON.parse

ccc6873

revert change to .blank?

95aa485

confirm both an object and an array within a JSON string can be parsed

c6c23ab

nicoledow added 2 commits August 22, 2025 12:24

update readme

678d787

update version

f96d633

nicoledow reviewed Aug 22, 2025

View reviewed changes

nicoledow added 2 commits August 22, 2025 12:27

typos in spec

2178759

update gemfile.lock to fix CI build

2a7e4f4

kweingart08 approved these changes Aug 26, 2025

View reviewed changes

nicoledow merged commit 48763ad into main Aug 29, 2025
6 checks passed

nicoledow deleted the feature/json-parse branch August 29, 2025 19:36

add json parser #140

add json parser #140

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dschadd commented Apr 24, 2023 • edited by nicoledow Loading Uh oh! There was an error while loading. Please reload this page.

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dschadd commented Apr 25, 2023

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dschadd commented Mar 11, 2025

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dschadd commented Apr 24, 2023 •

edited by nicoledow

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