Ethereum: Using abigen with combined json option generates nothing

Ethereum: Using ABigen with Combined-JSON option generates nothing

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

The problem:

You encountered unexpected behavior when trying to use the abigen command with the Combined-JSON option:

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.

The 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 UniswapV2PriceOracle.json file is passed as input to ABigen, but it is not actually processed by the command. Instead, a JSON object containing references to this file will be generated.

How ​​to Fix:

To fix this issue, you need to make sure that the output directory contains actual Go files instead of just references to other files. Here are some potential solutions:

• Move UniswapV2PriceOracle.json to the same directory as your main project:

If your project is structured like this:

project/
main.go
UniswapV2PriceOracle.json

You can move “UniswapV2PriceOracle.json” to the same directory as your “main.go” file:

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

• Use a different output directory:

If you need to keep your project organized, you can specify an output directory for the generated Go files:

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

• Use ABigen with a different input option:

Instead of using combined-json, you can try specifying the -target option 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 file “UniswapV2.go” with no references.

Conclusion:

To solve the problem of generating nothing when using ABigen with combined JSON, make sure that the output directory contains real Go files instead of just references to other files. You can fix this by moving “UniswapV2PriceOracle.json” to the same directory as your main project or by using a different output directory.

By following these steps, you should be able to generate working Go bindings for your Ethereum projects.

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