json

json

Export an F-Mesh mesh as indented JSON: its structure, or its state in one cycle of a run. Use it to feed other tools, diff two versions of a mesh, or snapshot a mesh in a test.

New() returns an Exporter. It implements this module's export.Exporter, like every format in this module. It has no options and no state: reuse one value for many meshes.

Install

go get github.com/hovsep/fmesh-export/json

Structure

import "github.com/hovsep/fmesh-export/json"

data, err := json.New().Export(fm)

{
  "name": "pricing",
  "meta": {"env": "prod"},
  "components": [
    {"name": "dst", "inputs": [{"name": "in"}], "outputs": []},
    {"name": "src", "description": "emits prices", "inputs": [], "outputs": [{"name": "out"}]}
  ],
  "pipes": [
    {"from": {"component": "src", "port": "out"}, "to": {"component": "dst", "port": "in"}}
  ]
}

• Components and ports are in name order. Pipes are grouped by source port, in the same order, and each port's pipes are in wiring order. The same mesh always exports the same bytes.
• description and meta are left out when empty. components, inputs, outputs and pipes are always present.
• Unmarshal into json.Mesh to read it back.

One cycle

ri, err := fm.Run(ctx)
for _, c := range ri.Cycles.All() {
    frame, err := json.New().ExportCycle(fm, c)
}

The document is a json.Cycle: the cycle number, the mesh structure, and one results entry per component, in name order:

{"component": "dst", "code": "Finished with error", "activated": true, "errors": ["component returned an error: boom"]}

• A component with no result in the cycle had no input: its code is No input.
• A nil mesh returns export.ErrNilMesh, and a nil cycle export.ErrNilCycle.
• To export each cycle while the mesh runs, call ExportCycle from an AfterCycle hook.

If you also import the standard library's encoding/json in the same file, give one of them an alias.