Ethereum: Using ABigen with the combined-JSON option generates nothing

As a developer working on Ethereum-related projects, it is not uncommon to encounter issues when trying to generate Go bindings using ABigen. In this article, we will delve into the issue and explore possible solutions.

Problem:

When trying to use the abigen command with the combined-JSON option, you encountered unexpected behavior:

abigen --combined-json UniswapV2PriceOracle.json --pkg abi --type UniswapV2 --out UniswapV2.go

As expected, you did not encounter any error messages. However, the generated Go file does not contain the expected structure.

Solution:

To solve this problem, let’s first understand what happens when we use abigen with combined JSON:

• The combined-json option tells ABigen to generate a JSON object that combines all the files specified in the input directory.

• When combined JSON is used, the generated file will contain references to the individual files instead of the actual code.

Why this happens:

In your case, you are using the following command:

abigen --combined-json UniswapV2PriceOracle.json --pkg abi --type UniswapV2 --out UniswapV2.go

The fileUniswapV2PriceOracle.jsonis passed as input to ABigen, but the command does not actually process it. Instead, a JSON object containing references to this file is generated.

• Move theUniswapV2PriceOracle.jsonfile to the same directory as your main project:

project/
main.go
UniswapV2PriceOracle.json

You can move the UniswapV2PriceOracle.jsonfile to the same directory as themain.gofile:

abigen UniswapV2PriceOracle.json --pkg abi --type UniswapV2 --out main.go

abigen --combined-json /path/to/output/directory/ UniswapV2PriceOracle.json --pkg abi --type UniswapV2 --out main.go

Instead of using combined-json, you can try specifying the-targetoption to tell ABigen what type of output to generate:

abigen -target go --pkg abi --type UniswapV2 UniswapV2PriceOracle.json

In this case, the generated Go file will contain a single UniswapV2.gofile with no references.

To fix the issue of nothing being generated when using ABigen with combined JSON, make sure that the output directory contains actual Go files instead of references to other files. You can fix this by moving theUniswapV2PriceOracle.json` file to the same directory as your main project or by using a different output directory.

Following these steps, you should be able to generate functional Go bindings for your Ethereum projects.

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